Vendor import of OpenBSD's pf userland as of OpenBSD 3.4

Approved by: bms(mentor), core(in general)

5 files changed, 3599 insertions, 0 deletions

diff --git a/contrib/pf/man/pf.4 b/contrib/pf/man/pf.4
new file mode 100644
index 0000000..f01dcb3
--- /dev/null
+++ b/contrib/pf/man/pf.4
@@ -0,0 +1,703 @@
+.\"	$OpenBSD: pf.4,v 1.37 2003/08/28 09:41:22 jmc Exp $
+.\"
+.\" Copyright (C) 2001, Kjell Wooding.  All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\" 3. Neither the name of the project nor the names of its contributors
+.\"    may be used to endorse or promote products derived from this software
+.\"    without specific prior written permission.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.Dd June 24, 2001
+.Dt PF 4
+.Os
+.Sh NAME
+.Nm pf
+.Nd packet filter
+.Sh SYNOPSIS
+.Cd "pseudo-device pf 1"
+.Sh DESCRIPTION
+Packet filtering takes place in the kernel.
+A pseudo-device,
+.Pa /dev/pf ,
+allows userland processes to control the
+behavior of the packet filter through an
+.Xr ioctl 2
+interface.
+There are commands to enable and disable the filter, load rulesets,
+add and remove individual rules or state table entries,
+and retrieve statistics.
+The most commonly used functions are covered by
+.Xr pfctl 8 .
+.Pp
+Manipulations like loading a ruleset that involve more than a single
+ioctl call require a so-called ticket, which prevents the occurrence of
+multiple concurrent manipulations.
+.Pp
+Fields of ioctl parameter structures that refer to packet data (like
+addresses and ports) are generally expected in network byte-order.
+.Sh FILES
+.Bl -tag -width /dev/pf -compact
+.It Pa /dev/pf
+packet filtering device.
+.El
+.Sh IOCTL INTERFACE
+pf supports the following
+.Xr ioctl 2
+commands:
+.Bl -tag -width xxxxxx
+.It Dv DIOCSTART
+Starts the packet filter.
+.It Dv DIOCSTOP
+Stops the packet filter.
+.It Dv DIOCSTARTALTQ
+Starts the ALTQ bandwidth control system.
+.It Dv DIOCSTOPALTQ
+Stops the ALTQ bandwidth control system.
+.It Dv DIOCBEGINADDRS  Fa "u_int32_t"
+Clears the buffer address pool
+and returns a ticket for subsequent DIOCADDADDR, DIOCADDRULE and
+DIOCCHANGERULE calls.
+.It Dv DIOCADDADDR     Fa "struct pfioc_pooladdr"
+.Bd -literal
+struct pfioc_pooladdr {
+	u_int32_t		action;
+	u_int32_t		ticket;
+	u_int32_t		nr;
+	u_int32_t		r_num;
+	u_int8_t		r_action;
+	u_int8_t		r_last;
+	u_int8_t		af;
+	char			anchor[PF_ANCHOR_NAME_SIZE];
+	char			ruleset[PF_RULESET_NAME_SIZE];
+	struct pf_pooladdr	addr;
+};
+.Ed
+.Pp
+Adds pool address
+.Va addr
+to the buffer address pool to be used in the following
+DIOCADDRULE or DIOCCHANGERULE call.
+All other members of the structure are ignored.
+.It Dv DIOCBEGINRULES  Fa "u_int32_t"
+Clears the inactive ruleset for the type of rule indicated by
+.Va rule.action
+and returns a ticket for subsequent
+DIOCADDRULE and DIOCCOMMITRULES calls.
+.It Dv DIOCADDRULE     Fa "struct pfioc_rule"
+.Bd -literal
+struct pfioc_rule {
+	u_int32_t	action;
+	u_int32_t	ticket;
+	u_int32_t	pool_ticket;
+	u_int32_t	nr;
+	char		anchor[PF_ANCHOR_NAME_SIZE];
+	char		ruleset[PF_RULESET_NAME_SIZE];
+	struct pf_rule	rule;
+};
+.Ed
+.Pp
+Adds
+.Va rule
+at the end of the inactive ruleset.
+Requires
+.Va ticket
+obtained through preceding DIOCBEGINRULES call, and
+.Va pool_ticket
+obtained through DIOCBEGINADDRS call.
+DIOCADDADDR must also be called if any pool addresses are required.
+The optional
+.Va anchor
+and
+.Va ruleset
+names indicate the anchor and ruleset in which to append the rule.
+.Va nr
+and
+.Va action
+are ignored.
+.It Dv DIOCCOMMITRULES Fa "u_int32_t"
+Switch inactive to active filter ruleset.
+Requires
+.Va ticket .
+.It Dv DIOCBEGINALTQS  Fa "u_int32_t"
+Clears the inactive list of queues and returns a ticket for subsequent
+DIOCADDALTQ and DIOCCOMMITALTQS calls.
+.It Dv DIOCADDALTQ     Fa "struct pfioc_altq"
+Adds
+.Bd -literal
+struct pfioc_altq {
+	u_int32_t	ticket;
+	u_int32_t	nr;
+	struct pf_altq   altq;
+};
+.Ed
+.It Dv DIOCCOMMITALTQS Fa "u_int32_t"
+Switch inactive to active list of queues.
+Requires
+.Va ticket .
+.It Dv DIOCGETRULES    Fa "struct pfioc_rule"
+Returns
+.Va ticket
+for subsequent DIOCGETRULE calls and
+.Va nr
+of rules in the active ruleset.
+.It Dv DIOCGETRULE     Fa "struct pfioc_rule"
+Returns
+.Va rule
+number
+.Va nr
+using
+.Va ticket
+obtained through a preceding DIOCGETRULES call.
+.It Dv DIOCGETADDRS    Fa "struct pfioc_pooladdr"
+Returns
+.Va ticket
+for subsequent DIOCGETADDR calls and
+.Va nr
+of pool addresses in the rule specified with
+.Va r_action ,
+.Va r_num ,
+.Va anchor
+and
+.Va ruleset .
+.It Dv DIOCGETADDR     Fa "struct pfioc_pooladdr"
+Returns pool address
+.Va addr
+number
+.Va nr
+from the rule specified with
+.Va r_action ,
+.Va r_num ,
+.Va anchor
+and
+.Va ruleset
+using
+.Va ticket
+obtained through a preceding DIOCGETADDRS call.
+.It Dv DIOCGETALTQS    Fa "struct pfioc_altq"
+Returns
+.Va ticket
+for subsequent DIOCGETALTQ calls and
+.Va nr
+of queues in the active list.
+.It Dv DIOCGETALTQ     Fa "struct pfioc_altq"
+Returns
+.Va altq
+number
+.Va nr
+using
+.Va ticket
+obtained through a preceding DIOCGETALTQS call.
+.It Dv DIOCGETQSTATS   Fa "struct pfioc_qstats"
+Returns statistics on a queue.
+.Bd -literal
+struct pfioc_qstats {
+	u_int32_t	 ticket;
+	u_int32_t	 nr;
+	void		*buf;
+	int		 nbytes;
+	u_int8_t	 scheduler;
+};
+.Ed
+.Pp
+A pointer to a buffer of statistics
+.Va buf
+of length
+.Va nbytes
+for the queue specified by
+.Va nr .
+.It Dv DIOCCLRSTATES
+Clears the state table.
+.It Dv DIOCADDSTATE    Fa "struct pfioc_state"
+Adds a state entry.
+.It Dv DIOCGETSTATE    Fa "struct pfioc_state"
+.Bd -literal
+struct pfioc_state {
+	u_int32_t	 nr;
+	struct pf_state	 state;
+};
+.Ed
+.Pp
+Extracts the entry with the specified number from the state table.
+.It Dv DIOCKILLSTATES  Fa "struct pfioc_state_kill"
+Removes matching entries from the state table.
+Returns the number of killed states in psk_af.
+.Bd -literal
+struct pfioc_state_kill {
+	int			psk_af;
+	int			psk_proto;
+	struct pf_rule_addr	psk_src;
+	struct pf_rule_addr	psk_dst;
+};
+.Ed
+.It Dv DIOCSETSTATUSIF Fa "struct pfioc_if"
+.Bd -literal
+struct pfioc_if {
+	char		 ifname[IFNAMSIZ];
+};
+.Ed
+.Pp
+Specifies the interface for which statistics are accumulated.
+.It Dv DIOCGETSTATUS   Fa "struct pf_status"
+.Bd -literal
+struct pf_status {
+	u_int64_t	 counters[PFRES_MAX];
+	u_int64_t	 fcounters[FCNT_MAX];
+	u_int64_t	 pcounters[2][2][3];
+	u_int64_t	 bcounters[2][2];
+	u_int32_t	 running;
+	u_int32_t	 states;
+	u_int32_t	 since;
+	u_int32_t	 debug;
+};
+.Ed
+.Pp
+Gets the internal packet filter statistics.
+.It Dv DIOCCLRSTATUS
+Clears the internal packet filter statistics.
+.It Dv DIOCNATLOOK     Fa "struct pfioc_natlook"
+Looks up a state table entry by source and destination addresses and ports.
+.Bd -literal
+struct pfioc_natlook {
+	struct pf_addr	 saddr;
+	struct pf_addr	 daddr;
+	struct pf_addr	 rsaddr;
+	struct pf_addr	 rdaddr;
+	u_int16_t	 sport;
+	u_int16_t	 dport;
+	u_int16_t	 rsport;
+	u_int16_t	 rdport;
+	u_int8_t	 af;
+	u_int8_t	 proto;
+	u_int8_t	 direction;
+};
+.Ed
+.It Dv DIOCSETDEBUG    Fa "u_int32_t"
+Sets the debug level.
+.Bd -literal
+enum	{ PF_DEBUG_NONE=0, PF_DEBUG_URGENT=1, PF_DEBUG_MISC=2 };
+.Ed
+.It Dv DIOCGETSTATES   Fa "struct pfioc_states"
+.Bd -literal
+struct pfioc_states {
+	int	ps_len;
+	union {
+		caddr_t psu_buf;
+		struct pf_state *psu_states;
+	} ps_u;
+#define ps_buf		ps_u.psu_buf
+#define ps_states	ps_u.psu_states
+};
+.Ed
+.It Dv DIOCCHANGERULE  Fa "struct pfioc_rule"
+Adds or removes the
+.Va rule
+in the ruleset specified by
+.Va rule.action .
+.Bd -literal
+enum	{ PF_CHANGE_ADD_HEAD=1, PF_CHANGE_ADD_TAIL=2,
+	  PF_CHANGE_ADD_BEFORE=3, PF_CHANGE_ADD_AFTER=4,
+	  PF_CHANGE_REMOVE=5, PF_CHANGE_GET_TICKET=6 };
+.Ed
+.Pp
+The type of operation to be performed is indicated by
+.Va action .
+.Pp
+.Va ticket
+must be set to the value obtained with PF_CHANGE_GET_TICKET
+for all actions except PF_CHANGE_GET_TICKET.
+.Va pool_ticket
+must be set to the value obtained with the DIOCBEGINADDRS call
+for all actions except PF_CHANGE_REMOVE and PF_CHANGE_GET_TICKET.
+.Pp
+.Va anchor
+and
+.Va ruleset
+indicate which anchor and ruleset the operation applies to.
+.Va nr
+indicates the rule number against which PF_CHANGE_ADD_BEFORE,
+PF_CHANGE_ADD_AFTER or PF_CHANGE_REMOVE actions are applied.
+.It Dv DIOCCHANGEADDR  Fa "struct pfioc_pooladdr"
+Adds or removes a pool address
+.Va addr
+from a rule specified with
+.Va r_action ,
+.Va r_num ,
+.Va anchor
+and
+.Va ruleset .
+.It Dv DIOCSETTIMEOUT  Fa "struct pfioc_tm"
+.Bd -literal
+struct pfioc_tm {
+	int		 timeout;
+	int		 seconds;
+};
+.Ed
+.It Dv DIOCGETTIMEOUT  Fa "struct pfioc_tm"
+.It Dv DIOCCLRRULECTRS
+Clear per-rule statistics.
+.It Dv DIOCSETLIMIT   Fa "struct pfioc_limit"
+Sets hard limits on the memory pools used by the packet filter.
+.Bd -literal
+struct pfioc_limit {
+	int		index;
+	unsigned	limit;
+};
+.Ed
+.It Dv DIOCGETLIMIT   Fa "struct pfioc_limit"
+.It Dv DIOCRCLRTABLES Fa "struct pfioc_table"
+Clear all tables.
+All the IOCTLs that manipulate radix tables
+use the same structure described below.
+For
+.Dv DIOCRCLRTABLES, pfrio_ndel contains on exit the number
+of tables deleted.
+.Bd -literal
+struct pfioc_table {
+        struct pfr_table         pfrio_table;
+        void                    *pfrio_buffer;
+        int                      pfrio_esize;
+        int                      pfrio_size;
+        int                      pfrio_size2;
+        int                      pfrio_nadd;
+        int                      pfrio_ndel;
+        int                      pfrio_nchange;
+        int                      pfrio_flags;
+        int                      pfrio_ticket;
+};
+#define pfrio_exists    pfrio_nadd
+#define pfrio_nzero     pfrio_nadd
+#define pfrio_nmatch    pfrio_nadd
+#define pfrio_naddr     pfrio_size2
+#define pfrio_setflag   pfrio_size2
+#define pfrio_clrflag   pfrio_nadd
+.Ed
+.It Dv DIOCRADDTABLES Fa "struct pfioc_table"
+Creates one or more tables.
+On entry, pfrio_buffer[pfrio_size] contains a table of pfr_table structures.
+On exit, pfrio_nadd contains the number of tables effectively created.
+.Bd -literal
+struct pfr_table {
+        char                     pfrt_anchor[PF_ANCHOR_NAME_SIZE];
+        char                     pfrt_ruleset[PF_RULESET_NAME_SIZE];
+        char                     pfrt_name[PF_TABLE_NAME_SIZE];
+        u_int32_t                pfrt_flags;
+        u_int8_t                 pfrt_fback;
+};
+.Ed
+.It Dv DIOCRDELTABLES Fa "struct pfioc_table"
+Deletes one or more tables.
+On entry, pfrio_buffer[pfrio_size] contains a table of pfr_table structures.
+On exit, pfrio_nadd contains the number of tables effectively deleted.
+.It Dv DIOCRGETTABLES Fa "struct pfioc_table"
+Get the list of all tables.
+On entry, pfrio_buffer[pfrio_size] contains a valid writeable buffer for
+pfr_table structures.
+On exit, pfrio_size contains the number of tables written into the buffer.
+If the buffer is too small, the kernel does not store anything but just
+returns the required buffer size, without error.
+.It Dv DIOCRGETTSTATS Fa "struct pfioc_table"
+Like
+.Dv DIOCRGETTABLES ,
+but returns an array of pfr_tstats structures.
+.Bd -literal
+struct pfr_tstats {
+        struct pfr_table pfrts_t;
+        u_int64_t        pfrts_packets
+                             [PFR_DIR_MAX][PFR_OP_TABLE_MAX];
+        u_int64_t        pfrts_bytes
+                             [PFR_DIR_MAX][PFR_OP_TABLE_MAX];
+        u_int64_t        pfrts_match;
+        u_int64_t        pfrts_nomatch;
+        long             pfrts_tzero;
+        int              pfrts_cnt;
+        int              pfrts_refcnt[PFR_REFCNT_MAX];
+};
+#define pfrts_name      pfrts_t.pfrt_name
+#define pfrts_flags     pfrts_t.pfrt_flags
+.Ed
+.It Dv DIOCRCLRTSTATS Fa "struct pfioc_table"
+Clears the statistics of one or more tables.
+On entry, pfrio_buffer[pfrio_size] contains a table of pfr_table structures.
+On exit, pfrio_nzero contains the number of tables effectively cleared.
+.It Dv DIOCRCLRADDRS Fa "struct pfioc_table"
+Clear all addresses in a table.
+On entry, pfrio_table contains the table to clear.
+On exit, pfrio_ndel contains the number of addresses removed.
+.It Dv DIOCRADDADDRS Fa "struct pfioc_table"
+Add one or more addresses to a table.
+On entry, pfrio_table contains the table id and pfrio_buffer[pfrio_size]
+contains the list of pfr_addr structures to add.
+On exit, pfrio_nadd contains the number of addresses effectively added.
+.Bd -literal
+struct pfr_addr {
+        union {
+                struct in_addr   _pfra_ip4addr;
+                struct in6_addr  _pfra_ip6addr;
+        }                pfra_u;
+        u_int8_t         pfra_af;
+        u_int8_t         pfra_net;
+        u_int8_t         pfra_not;
+        u_int8_t         pfra_fback;
+};
+#define pfra_ip4addr    pfra_u._pfra_ip4addr
+#define pfra_ip6addr    pfra_u._pfra_ip6addr
+.Ed
+.It Dv DIOCRDELADDRS Fa "struct pfioc_table"
+Delete one or more addresses from a table.
+On entry, pfrio_table contains the table id and pfrio_buffer[pfrio_size]
+contains the list of pfr_addr structures to delete.
+On exit, pfrio_ndel contains the number of addresses effectively deleted.
+.It Dv DIOCRSETADDRS Fa "struct pfioc_table"
+Replace the content of a table by a new address list.
+This is the most complicated command, which uses all the structure members.
+On entry, pfrio_table contains the table id and pfrio_buffer[pfrio_size]
+contains the new list of pfr_addr structures.
+In addition to that, if size2 is nonzero, pfrio_buffer[pfrio_size..pfrio_size2]
+must be a writeable buffer, into which the kernel can copy the addresses that
+have been deleted during the replace operation.
+On exit, pfrio_ndel, pfrio_nadd and pfrio_nchange contain the number of
+addresses deleted, added and changed by the kernel.
+If pfrio_size2 was set on
+entry, pfrio_size2 will point to the size of the buffer used, exactly like
+.Dv DIOCRGETADDRS .
+.It Dv DIOCRGETADDRS Fa "struct pfioc_table"
+Get all the addresses of a table.
+On entry, pfrio_table contains the table id and pfrio_buffer[pfrio_size]
+contains a valid writeable buffer for pfr_addr structures.
+On exit, pfrio_size contains the number of addresses written into the buffer.
+If the buffer was too small, the kernel does not store anything but just
+return the required buffer size, without returning an error.
+.It Dv DIOCRGETASTATS Fa "struct pfioc_table"
+Like
+.Dv DIOCRGETADDRS ,
+but returns an array of pfr_astats structures.
+.Bd -literal
+struct pfr_astats {
+        struct pfr_addr  pfras_a;
+        u_int64_t        pfras_packets
+                             [PFR_DIR_MAX][PFR_OP_ADDR_MAX];
+        u_int64_t        pfras_bytes
+                             [PFR_DIR_MAX][PFR_OP_ADDR_MAX];
+        long             pfras_tzero;
+};
+.Ed
+.It Dv DIOCRCLRASTATS Fa "struct pfioc_table"
+Clears the statistics of one or more addresses.
+On entry, pfrio_table contains the table id and pfrio_buffer[pfrio_size]
+contains a table of pfr_addr structures to clear.
+On exit, pfrio_nzero contains the number of addresses effectively cleared.
+.It Dv DIOCRTSTADDRS Fa "struct pfioc_table"
+Test if the given addresses match a table.
+On entry, pfrio_table contains the table id and pfrio_buffer[pfrio_size]
+contains a table of pfr_addr structures to test.
+On exit, the kernel updates the pfr_addr table by setting the pfra_fback
+member appropriately.
+.It Dv DIOCRSETTFLAGS Fa "struct pfioc_table"
+Change the
+.Va const
+or
+.Va persist
+flag of a table.
+On entry, pfrio_buffer[pfrio_size] contains a table of pfr_table structures,
+and pfrio_setflag contains the flags to add, while pfrio_clrflag contains the
+flags to remove.
+On exit, pfrio_nchange and pfrio_ndel contain the number of tables altered
+or deleted by the kernel.
+Yes, tables can be deleted if one removes the
+.Va persist
+flag of an unreferenced table.
+.It Dv DIOCRINABEGIN Fa "struct pfioc_table"
+Starts a transaction with the inactive set of tables.
+Cleans up any leftover from a previously aborted transaction, and returns
+a new ticket.
+On exit, pfrio_ndel contains the number of leftover table deleted, and
+pfrio_ticket contains a valid ticket to use for the following two IOCTLs.
+.It Dv DIOCRINACOMMIT Fa "struct pfioc_table"
+Commit the inactive set of tables into the active set.
+While copying the addresses, do a best effort to keep statistics for
+addresses present before and after the commit.
+On entry, io->pfrio_ticket takes a valid ticket.
+On exit, io->pfrio_nadd and io->pfrio_nchange contain the number of tables
+added and altered by the commit operation.
+.It Dv DIOCRINADEFINE Fa "struct pfioc_table"
+Defines a table in the inactive set.
+On entry, pfrio_table contains the table id and pfrio_buffer[pfrio_size]
+contains the list of pfr_addr structures to put in the table.
+A valid ticket must also be supplied to pfrio_ticket.
+On exit, pfrio_nadd contains 0 if the table was already defined in the
+inactive list, or 1 if a new table has been created.
+pfrio_naddr contains the number of addresses effectively put in the table.
+.It Dv DIOCFPFLUSH
+Flush the passive OS fingerprint table.
+.It Dv DIOCFPADD Fa "struct pf_osfp_ioctl"
+.Bd -literal
+struct pf_osfp_ioctl {
+	struct pf_osfp_entry {
+		SLIST_ENTRY(pf_osfp_entry) fp_entry;
+		pf_osfp_t		fp_os;
+		char			fp_class_nm[PF_OSFP_LEN];
+		char			fp_version_nm[PF_OSFP_LEN];
+		char			fp_subtype_nm[PF_OSFP_LEN];
+	} 			fp_os;
+	u_int16_t		fp_mss;
+	u_int16_t		fp_wsize;
+	u_int16_t		fp_psize;
+	u_int8_t		fp_ttl;
+	u_int8_t		fp_wscale;
+	u_int8_t		fp_flags;
+	int			fp_getnum;
+};
+.Ed
+.Pp
+Add a passive OS fingerprint to the table.
+Set
+.Va fp_os.fp_os
+to the packed fingerprint,
+.Va fp_os.fp_class_nm
+to the name of the class (Linux, Windows, etc),
+.Va fp_os.fp_version_nm
+to the name of the version (NT, 95, 98), and
+.Va fp_os.fp_subtype_nm
+to the name of the subtype or patchlevel.
+The members
+.Va fp_mss ,
+.Va fp_wsize ,
+.Va fp_psize ,
+.Va fp_ttl ,
+and
+.Va fp_wscale
+are set to the TCP MSS, the TCP window size, the IP length and the IP TTL of
+the TCP SYN packet respectively.
+The
+.Va fp_flags
+member is filled according to the net/pfvar.h include file PF_OSFP_* defines.
+The
+.Va fp_getnum
+is not used with this ioctl.
+.Pp
+The structure's slack space must be zeroed for correct operation; memset
+the whole structure to zero before filling and sending to the kernel.
+.It Dv DIOCFPGET Fa "struct pf_osfp_ioctl"
+.Bd -literal
+struct pf_osfp_ioctl {
+	struct pf_osfp_entry {
+		SLIST_ENTRY(pf_osfp_entry) fp_entry;
+		pf_osfp_t		fp_os;
+		char			fp_class_nm[PF_OSFP_LEN];
+		char			fp_version_nm[PF_OSFP_LEN];
+		char			fp_subtype_nm[PF_OSFP_LEN];
+	} 			fp_os;
+	u_int16_t		fp_mss;
+	u_int16_t		fp_wsize;
+	u_int16_t		fp_psize;
+	u_int8_t		fp_ttl;
+	u_int8_t		fp_wscale;
+	u_int8_t		fp_flags;
+	int			fp_getnum;
+};
+.Ed
+.Pp
+Get the passive OS fingerprint number
+.Va fp_getnum
+from the kernel's fingerprint list.
+The rest of the structure members will come back filled.
+Get the whole list by repeatedly incrementing the
+.Va fp_getnum
+number until the ioctl returns EBUSY.
+.El
+.Sh EXAMPLES
+The following example demonstrates how to use the DIOCNATLOOK command
+to find the internal host/port of a NATed connection.
+.Bd -literal
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/ioctl.h>
+#include <sys/fcntl.h>
+#include <net/if.h>
+#include <netinet/in.h>
+#include <net/pfvar.h>
+#include <err.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+u_int32_t
+read_address(const char *s)
+{
+	int a, b, c, d;
+
+	sscanf(s, "%i.%i.%i.%i", &a, &b, &c, &d);
+	return htonl(a << 24 | b << 16 | c << 8 | d);
+}
+
+void
+print_address(u_int32_t a)
+{
+	a = ntohl(a);
+	printf("%d.%d.%d.%d", a >> 24 & 255, a >> 16 & 255,
+	    a >> 8 & 255, a & 255);
+}
+
+int
+main(int argc, char *argv[])
+{
+	struct pfioc_natlook nl;
+	int dev;
+
+	if (argc != 5) {
+		printf("%s <gwy addr> <gwy port> <ext addr> <ext port>\\n",
+		    argv[0]);
+		return 1;
+	}
+
+	dev = open("/dev/pf", O_RDWR);
+	if (dev == -1)
+		err(1, "open(\\"/dev/pf\\") failed");
+
+	memset(&nl, 0, sizeof(struct pfioc_natlook));
+	nl.saddr.v4.s_addr	= read_address(argv[1]);
+	nl.sport		= htons(atoi(argv[2]));
+	nl.daddr.v4.s_addr	= read_address(argv[3]);
+	nl.dport		= htons(atoi(argv[4]));
+	nl.af			= AF_INET;
+	nl.proto		= IPPROTO_TCP;
+	nl.direction		= PF_IN;
+
+	if (ioctl(dev, DIOCNATLOOK, &nl))
+		err(1, "DIOCNATLOOK");
+
+	printf("internal host ");
+	print_address(nl.rsaddr.v4.s_addr);
+	printf(":%u\\n", ntohs(nl.rsport));
+	return 0;
+}
+.Ed
+.Sh SEE ALSO
+.Xr ioctl 2 ,
+.Xr bridge 4 ,
+.Xr pflog 4 ,
+.Xr pfsync 4 ,
+.Xr pfctl 8
+.Sh HISTORY
+The
+.Nm
+packet filtering mechanism first appeared in
+.Ox 3.0 .
diff --git a/contrib/pf/man/pf.conf.5 b/contrib/pf/man/pf.conf.5
new file mode 100644
index 0000000..9881318
--- /dev/null
+++ b/contrib/pf/man/pf.conf.5
@@ -0,0 +1,2486 @@
+.\"	$OpenBSD: pf.conf.5,v 1.271 2003/09/02 18:37:08 jmc Exp $
+.\"
+.\" Copyright (c) 2002, Daniel Hartmeier
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\"
+.\"    - Redistributions of source code must retain the above copyright
+.\"      notice, this list of conditions and the following disclaimer.
+.\"    - Redistributions in binary form must reproduce the above
+.\"      copyright notice, this list of conditions and the following
+.\"      disclaimer in the documentation and/or other materials provided
+.\"      with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+.\" "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+.\" LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+.\" FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+.\" COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+.\" ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+.\" POSSIBILITY OF SUCH DAMAGE.
+.\"
+.Dd November 19, 2002
+.Dt PF.CONF 5
+.Os
+.Sh NAME
+.Nm pf.conf
+.Nd packet filter configuration file
+.Sh DESCRIPTION
+The
+.Xr pf 4
+packet filter modifies, drops or passes packets according to rules or
+definitions specified in
+.Nm pf.conf .
+.Sh STATEMENT ORDER
+There are seven types of statements in
+.Nm pf.conf :
+.Bl -tag -width xxxx
+.It Cm Macros
+User-defined variables may be defined and used later, simplifying
+the configuration file.
+Macros must be defined before they are referenced in
+.Nm pf.conf .
+.It Cm Tables
+Tables provide a mechanism for increasing the performance and flexibility of
+rules with large numbers of source or destination addresses.
+.It Cm Options
+Options tune the behaviour of the packet filtering engine.
+.It Cm Traffic Normalization Li (e.g. Em scrub )
+Traffic normalization protects internal machines against inconsistencies
+in Internet protocols and implementations.
+.It Cm Queueing
+Queueing provides rule-based bandwidth control.
+.It Cm Translation Li (Various forms of NAT)
+Translation rules specify how addresses are to be mapped or redirected to
+other addresses.
+.It Cm Packet Filtering
+Stateful and stateless packet filtering provides rule-based blocking or
+passing of packets.
+.El
+.Pp
+With the exception of
+.Cm macros
+and
+.Cm tables ,
+the types of statements should be grouped and appear in
+.Nm pf.conf
+in the order shown above, as this matches the operation of the underlying
+packet filtering engine.
+By default
+.Xr pfctl 8
+enforces this order (see
+.Ar set require-order
+below).
+.Sh MACROS
+Much like
+.Xr cpp 1
+or
+.Xr m4 1 ,
+macros can be defined that will later be expanded in context.
+Macro names must start with a letter, and may contain letters, digits
+and underscores.
+Macro names may not be reserved words (for example
+.Ar pass ,
+.Ar in ,
+.Ar out ) .
+Macros are not expanded inside quotes.
+.Pp
+For example,
+.Bd -literal -offset indent
+ext_if = \&"kue0\&"
+all_ifs = \&"{\&" $ext_if lo0 \&"}\&"
+pass out on $ext_if from any to any keep state
+pass in  on $ext_if proto tcp from any to any port 25 keep state
+.Ed
+.Sh TABLES
+Tables are named structures which can hold a collection of addresses and
+networks.
+Lookups against tables in
+.Xr pf 4
+are relatively fast, making a single rule with tables much more efficient,
+in terms of
+processor usage and memory consumption, than a large number of rules which
+differ only in IP address (either created explicitly or automatically by rule
+expansion).
+.Pp
+Tables can be used as the source or destination of filter rules,
+.Ar scrub
+rules
+or
+translation rules such as
+.Ar nat
+or
+.Ar rdr
+(see below for details on the various rule types).
+Tables can also be used for the redirect address of
+.Ar nat
+and
+.Ar rdr
+rules and in the routing options of filter rules, but only for
+.Ar round-robin
+pools.
+.Pp
+Tables can be defined with any of the following
+.Xr pfctl 8
+mechanisms.
+As with macros, reserved words may not be used as table names.
+.Bl -tag -width "manually"
+.It Ar manually
+Persistent tables can be manually created with the
+.Ar add
+or
+.Ar replace
+option of
+.Xr pfctl 8 ,
+before or after the ruleset has been loaded.
+.It Pa pf.conf
+Table definitions can be placed directly in this file, and loaded at the
+same time as other rules are loaded, atomically.
+Table definitions inside
+.Nm pf.conf
+use the
+.Ar table
+statement, and are especially useful to define non-persistent tables.
+The contents of a pre-existing table defined without a list of addresses
+to initialize it is not altered when
+.Nm pf.conf
+is loaded.
+A table initialized with the empty list,
+.Li { } ,
+will be cleared on load.
+.El
+.Pp
+Tables may be defined with the following two attributes:
+.Bl -tag -width persist
+.It Ar persist
+The
+.Ar persist
+flag forces the kernel to keep the table even when no rules refer to it.
+If the flag is not set, the kernel will automatically remove the table
+when the last rule referring to it is flushed.
+.It Ar const
+The
+.Ar const
+flag prevents the user from altering the contents of the table once it
+has been created.
+Without that flag,
+.Xr pfctl 8
+can be used to add or remove addresses from the table at any time, even
+when running with
+.Xr securelevel 7
+= 2.
+.El
+.Pp
+For example,
+.Bd -literal -offset indent
+table <private> const { 10/8, 172.16/12, 192.168/16 }
+table <badhosts> persist
+block on fxp0 from { <private>, <badhosts> } to any
+.Ed
+.Pp
+creates a table called private, to hold RFC 1918 private network
+blocks, and a table called badhosts, which is initially empty.
+A filter rule is set up to block all traffic coming from addresses listed in
+either table.
+The private table cannot have its contents changed and the badhosts table
+will exist even when no active filter rules reference it.
+Addresses may later be added to the badhosts table, so that traffic from
+these hosts can be blocked by using
+.Bd -literal -offset indent
+# pfctl -t badhosts -Tadd 204.92.77.111
+.Ed
+.Pp
+A table can also be initialized with an address list specified in one or more
+external files, using the following syntax:
+.Bd -literal -offset indent
+table <spam> persist file \&"/etc/spammers\&" file \&"/etc/openrelays\&"
+block on fxp0 from <spam> to any
+.Ed
+.Pp
+The files
+.Pa /etc/spammers
+and
+.Pa /etc/openrelays
+list IP addresses, one per line.
+Any lines beginning with a # are treated as comments and ignored.
+In addition to being specified by IP address, hosts may also be
+specified by their hostname.
+When the resolver is called to add a hostname to a table,
+.Em all
+resulting IPv4 and IPv6 addresses are placed into the table.
+IP addresses can also be entered in a table by specifying a valid interface
+name or the
+.Em self
+keyword, in which case all addresses assigned to the interface(s) will be
+added to the table.
+.Sh OPTIONS
+.Xr pf 4
+may be tuned for various situations using the
+.Ar set
+command.
+.Bl -tag -width xxxx
+.It Ar set timeout
+.Pp
+.Bl -tag -width interval -compact
+.It Ar interval
+Interval between purging expired states and fragments.
+.It Ar frag
+Seconds before an unassembled fragment is expired.
+.El
+.Pp
+When a packet matches a stateful connection, the seconds to live for the
+connection will be updated to that of the
+.Ar proto.modifier
+which corresponds to the connection state.
+Each packet which matches this state will reset the TTL.
+Tuning these values may improve the performance of the
+firewall at the risk of dropping valid idle connections.
+.Pp
+.Bl -tag -width xxxx -compact
+.It Ar tcp.first
+The state after the first packet.
+.It Ar tcp.opening
+The state before the destination host ever sends a packet.
+.It Ar tcp.established
+The fully established state.
+.It Ar tcp.closing
+The state after the first FIN has been sent.
+.It Ar tcp.finwait
+The state after both FINs have been exchanged and the connection is closed.
+Some hosts (notably web servers on Solaris) send TCP packets even after closing
+the connection.
+Increasing
+.Ar tcp.finwait
+(and possibly
+.Ar tcp.closing )
+can prevent blocking of such packets.
+.It Ar tcp.closed
+The state after one endpoint sends an RST.
+.El
+.Pp
+ICMP and UDP are handled in a fashion similar to TCP, but with a much more
+limited set of states:
+.Pp
+.Bl -tag -width xxxx -compact
+.It Ar udp.first
+The state after the first packet.
+.It Ar udp.single
+The state if the source host sends more than one packet but the destination
+host has never sent one back.
+.It Ar udp.multiple
+The state if both hosts have sent packets.
+.It Ar icmp.first
+The state after the first packet.
+.It Ar icmp.error
+The state after an ICMP error came back in response to an ICMP packet.
+.El
+.Pp
+Other protocols are handled similarly to UDP:
+.Pp
+.Bl -tag -width xxxx -compact
+.It Ar other.first
+.It Ar other.single
+.It Ar other.multiple
+.El
+.Pp
+Timeout values can be reduced adaptively as the number of state table
+entries grows.
+.Pp
+.Bl -tag -width xxxx -compact
+.It Ar adaptive.start
+When the number of state entries exceeds this value, adaptive scaling
+begins.
+All timeout values are scaled linearly with factor
+(adaptive.end - number of states) / (adaptive.end - adaptive.start).
+.It Ar adaptive.end
+When reaching this number of state entries, all timeout values become
+zero, effectively purging all state entries immediately.
+This value is used to define the scale factor, it should not actually
+be reached (set a lower state limit, see below).
+.El
+.Pp
+These values can be defined both globally and for each rule.
+When used on a per-rule basis, the values relate to the number of
+states created by the rule, otherwise to the total number of
+states.
+.Pp
+For example:
+.Bd -literal -offset indent
+set timeout tcp.first 120
+set timeout tcp.established 86400
+set timeout { adaptive.start 6000, adaptive.end 12000 }
+set limit states 10000
+.Ed
+.Pp
+With 9000 state table entries, the timeout values are scaled to 50%
+(tcp.first 60, tcp.established 43200).
+.Pp
+.It Ar set loginterface
+Enable collection of packet and byte count statistics for the given interface.
+These statistics can be viewed using
+.Bd -literal -offset indent
+# pfctl -s info
+.Ed
+.Pp
+In this example
+.Xr pf 4
+collects statistics on the interface named dc0:
+.Bd -literal -offset indent
+set loginterface dc0
+.Ed
+.Pp
+One can disable the loginterface using:
+.Bd -literal -offset indent
+set loginterface none
+.Ed
+.Pp
+.It Ar set limit
+Sets hard limits on the memory pools used by the packet filter.
+See
+.Xr pool 9
+for an explanation of memory pools.
+.Pp
+For example,
+.Bd -literal -offset indent
+set limit states 20000
+.Ed
+.Pp
+sets the maximum number of entries in the memory pool used by state table
+entries (generated by
+.Ar keep state
+rules) to 20000.
+Using
+.Bd -literal -offset indent
+set limit frags 20000
+.Ed
+.Pp
+sets the maximum number of entries in the memory pool used for fragment
+reassembly (generated by
+.Ar scrub
+rules) to 20000.
+.Pp
+These can be combined:
+.Bd -literal -offset indent
+set limit { states 20000, frags 20000 }
+.Ed
+.Pp
+.It Ar set optimization
+Optimize the engine for one of the following network environments:
+.Pp
+.Bl -tag -width xxxx -compact
+.It Ar normal
+A normal network environment.
+Suitable for almost all networks.
+.It Ar high-latency
+A high-latency environment (such as a satellite connection).
+.It Ar satellite
+Alias for
+.Ar high-latency .
+.It Ar aggressive
+Aggressively expire connections.
+This can greatly reduce the memory usage of the firewall at the cost of
+dropping idle connections early.
+.It Ar conservative
+Extremely conservative settings.
+Avoid dropping legitimate connections at the
+expense of greater memory utilization (possibly much greater on a busy
+network) and slightly increased processor utilization.
+.El
+.Pp
+For example:
+.Bd -literal -offset indent
+set optimization aggressive
+.Ed
+.Pp
+.It Ar set block-policy
+The
+.Ar block-policy
+option sets the default behaviour for the packet
+.Ar block
+action:
+.Pp
+.Bl -tag -width xxxxxxxx -compact
+.It Ar drop
+Packet is silently dropped.
+.It Ar return
+A TCP RST is returned for blocked TCP packets,
+an ICMP UNREACHABLE is returned for blocked UDP packets,
+and all other packets are silently dropped.
+.El
+.Pp
+For example:
+.Bd -literal -offset indent
+set block-policy return
+.Ed
+.It Ar set require-order
+By default
+.Xr pfctl 8
+enforces an ordering of the statement types in the ruleset to:
+.Em options ,
+.Em normalization ,
+.Em queueing ,
+.Em translation ,
+.Em filtering .
+Setting this option to
+.Ar no
+disables this enforcement.
+There may be non-trivial and non-obvious implications to an out of
+order ruleset.
+Consider carefully before disabling the order enforcement.
+.It Ar set fingerprints
+Load fingerprints of known operating systems from the given filename.
+By default fingerprints of known operating systems are automatically
+loaded from
+.Xr pf.os 5
+in
+.Pa /etc
+but can be overridden via this option.
+Setting this option may leave a small period of time where the fingerprints
+referenced by the currently active ruleset are inconsistent until the new
+ruleset finishes loading.
+.Pp
+For example:
+.Pp
+.Dl set fingerprints \&"/etc/pf.os.devel\&"
+.El
+.Sh TRAFFIC NORMALIZATION
+Traffic normalization is used to sanitize packet content in such
+a way that there are no ambiguities in packet interpretation on
+the receiving side.
+The normalizer does IP fragment reassembly to prevent attacks
+that confuse intrusion detection systems by sending overlapping
+IP fragments.
+Packet normalization is invoked with the
+.Ar scrub
+directive.
+.Pp
+.Ar scrub
+has the following options:
+.Bl -tag -width xxxx
+.It Ar no-df
+Clears the
+.Ar dont-fragment
+bit from a matching IP packet.
+Some operating systems are known to generate fragmented packets with the
+.Ar dont-fragment
+bit set.
+This is particularly true with NFS.
+.Ar Scrub
+will drop such fragmented
+.Ar dont-fragment
+packets unless
+.Ar no-df
+is specified.
+.Pp
+Unfortunately some operating systems also generate their
+.Ar dont-fragment
+packets with a zero IP identification field.
+Clearing the
+.Ar dont-fragment
+bit on packets with a zero IP ID may cause deleterious results if an
+upstream router later fragments the packet.
+Using the
+.Ar random-id
+modifier (see below) is recommended in combination with the
+.Ar no-df
+modifier to ensure unique IP identifiers.
+.It Ar min-ttl <number>
+Enforces a minimum TTL for matching IP packets.
+.It Ar max-mss <number>
+Enforces a maximum MSS for matching TCP packets.
+.It Ar random-id
+Replaces the IP identification field with random values to compensate
+for predictable values generated by many hosts.
+This option only applies to outgoing packets that are not fragmented
+after the optional fragment reassembly.
+.It Ar fragment reassemble
+Using
+.Ar scrub
+rules, fragments can be reassembled by normalization.
+In this case, fragments are buffered until they form a complete
+packet, and only the completed packet is passed on to the filter.
+The advantage is that filter rules have to deal only with complete
+packets, and can ignore fragments.
+The drawback of caching fragments is the additional memory cost.
+But the full reassembly method is the only method that currently works
+with NAT.
+This is the default behavior of a
+.Ar scrub
+rule if no fragmentation modifier is supplied.
+.It Ar fragment crop
+The default fragment reassembly method is expensive, hence the option
+to crop is provided.
+In this case,
+.Xr pf 4
+will track the fragments and cache a small range descriptor.
+Duplicate fragments are dropped and overlaps are cropped.
+Thus data will only occur once on the wire with ambiguities resolving to
+the first occurrence.
+Unlike the
+.Ar fragment reassemble
+modifier, fragments are not buffered, they are passed as soon as they
+are received.
+The
+.Ar fragment crop
+reassembly mechanism does not yet work with NAT.
+.Pp
+.It Ar fragment drop-ovl
+This option is similar to the
+.Ar fragment crop
+modifier except that all overlapping or duplicate fragments will be
+dropped, and all further corresponding fragments will be
+dropped as well.
+.It Ar reassemble tcp
+Statefully normalizes TCP connections.
+.Ar scrub reassemble tcp
+rules may not have the direction (in/out) specified.
+.Ar reassemble tcp
+performs the following normalizations:
+.Pp
+.Bl -tag -width timeout -compact
+.It ttl
+Neither side of the connection is allowed to reduce their IP TTL.
+An attacker may send a packet such that it reaches the firewall, affects
+the firewall state, and expires before reaching the destination host.
+.Ar reassemble tcp
+will raise the TTL of all packets back up to the highest value seen on
+the connection.
+.It timeout modulation
+Modern TCP stacks will send a timestamp on every TCP packet and echo
+the other endpoint's timestamp back to them.
+Many operating systems will merely start the timestamp at zero when
+first booted, and increment it several times a second.
+The uptime of the host can be deduced by reading the timestamp and multiplying
+by a constant.
+Also observing several different timestamps can be used to count hosts
+behind a NAT device.
+And spoofing TCP packets into a connection requires knowing or guessing
+valid timestamps.
+Timestamps merely need to be monotonically increasing and not derived off a
+guessable base time.
+.Ar reassemble tcp
+will cause
+.Ar scrub
+to modulate the TCP timestamps with a random number.
+.El
+.El
+.Pp
+For example,
+.Bd -literal -offset indent
+scrub in on $ext_if all fragment reassemble
+.Ed
+.Sh QUEUEING
+Packets can be assigned to queues for the purpose of bandwidth
+control.
+At least two declarations are required to configure queues, and later
+any packet filtering rule can reference the defined queues by name.
+During the filtering component of
+.Nm pf.conf ,
+the last referenced
+.Ar queue
+name is where any packets from
+.Ar pass
+rules will be queued, while for
+.Ar block
+rules it specifies where any resulting ICMP or TCP RST
+packets should be queued.
+The
+.Ar scheduler
+defines the algorithm used to decide which packets get delayed, dropped, or
+sent out immediately.
+There are three
+.Ar schedulers
+currently supported.
+.Bl -tag -width xxxx
+.It Ar cbq
+Class Based Queueing.
+.Ar Queues
+attached to an interface build a tree, thus each
+.Ar queue
+can have further child
+.Ar queues .
+Each queue can have a
+.Ar priority
+and a
+.Ar bandwidth
+assigned.
+.Ar Priority
+mainly controls the time packets take to get sent out, while
+.Ar bandwidth
+has primarily effects on throughput.
+.It Ar priq
+Priority Queueing.
+.Ar Queues
+are flat attached to the interface, thus,
+.Ar queues
+cannot have further child
+.Ar queues .
+Each
+.Ar queue
+has a unique
+.Ar priority
+assigned, ranging from 0 to 15.
+Packets in the
+.Ar queue
+with the highest
+.Ar priority
+are processed first.
+.It Ar hfsc
+Hierarchical Fair Service Curve.
+.Ar Queues
+attached to an interface build a tree, thus each
+.Ar queue
+can have further child
+.Ar queues .
+Each queue can have a
+.Ar priority
+and a
+.Ar bandwidth
+assigned.
+.Ar Priority
+mainly controls the time packets take to get sent out, while
+.Ar bandwidth
+has primarily effects on throughput.
+.El
+.Pp
+The interfaces on which queueing should be activated are declared using
+the
+.Ar altq on
+declaration.
+.Ar altq on
+has the following keywords:
+.Bl -tag -width xxxx
+.It Ar <interface>
+Queueing is enabled on the named interface.
+.It Ar <scheduler>
+Specifies which queueing scheduler to use.
+Currently supported values
+are
+.Ar cbq
+for Class Based Queueing,
+.Ar priq
+for Priority Queueing and
+.Ar hfsc
+for the Hierarchical Fair Service Curve scheduler.
+.It Ar bandwidth <bw>
+The maximum bitrate for all queues on an
+interface may be specified using the
+.Ar bandwidth
+keyword.
+The value can be specified as an absolute value or as a
+percentage of the interface bandwidth.
+When using an absolute value, the suffixes
+.Ar b ,
+.Ar Kb ,
+.Ar Mb ,
+and
+.Ar Gb
+are used to represent bits, kilobits, megabits, and
+gigabits per second, respectively.
+The value must not exceed the interface bandwidth.
+If
+.Ar bandwidth
+is not specified, the interface bandwidth is used.
+.It Ar qlimit <limit>
+The maximum number of packets held in the queue.
+The default is 50.
+.It Ar tbrsize <size>
+Adjusts the size, in bytes, of the token bucket regulator.
+If not specified, heuristics based on the
+interface bandwidth are used to determine the size.
+.It Ar queue <list>
+Defines a list of subqueues to create on an interface.
+.El
+.Pp
+In the following example, the interface dc0
+should queue up to 5 Mbit/s in four second-level queues using
+Class Based Queueing.
+Those four queues will be shown in a later example.
+.Bd -literal -offset indent
+altq on dc0 cbq bandwidth 5Mb queue { std, http, mail, ssh }
+.Ed
+.Pp
+Once interfaces are activated for queueing using the
+.Ar altq
+directive, a sequence of
+.Ar queue
+directives may be defined.
+The name associated with a
+.Ar queue
+must match a queue defined in the
+.Ar altq
+directive (e.g. mail), or, except for the
+.Ar priq
+.Ar scheduler ,
+in a parent
+.Ar queue
+declaration.
+The following keywords can be used:
+.Bl -tag -width xxxx
+.It Ar on <interface>
+Specifies the interface the queue operates on.
+If not given, it operates on all matching interfaces.
+.It Ar bandwidth <bw>
+Specifies the maximum bitrate to be processed by the queue.
+This value must not exceed the value of the parent
+.Ar queue
+and can be specified as an absolute value or a percentage of the parent
+queue's bandwidth.
+The
+.Ar priq
+scheduler does not support bandwidth specification.
+.It Ar priority <level>
+Between queues a priority level can be set.
+For
+.Ar cbq
+and
+.Ar hfsc ,
+the range is 0 to 7 and for
+.Ar priq ,
+the range is 0 to 15.
+The default for all is 1.
+.Ar Priq
+queues with a higher priority are always served first.
+.Ar Cbq
+and
+.Ar Hfsc
+queues with a higher priority are preferred in the case of overload.
+.It Ar qlimit <limit>
+The maximum number of packets held in the queue.
+The default is 50.
+.El
+.Pp
+The
+.Ar scheduler
+can get additional parameters with
+.Ar <scheduler> Ns Li (\& Ar <parameters> No ) .
+Parameters are as follows:
+.Bl -tag -width Fl
+.It Ar default
+Packets not matched by another queue are assigned to this one.
+Exactly one default queue is required.
+.It Ar red
+Enable RED (Random Early Detection) on this queue.
+RED drops packets with a probability proportional to the average
+queue length.
+.It Ar rio
+Enables RIO on this queue.
+RIO is RED with IN/OUT, thus running
+RED two times more than RIO would achieve the same effect.
+RIO is currently not supported in the GENERIC kernel.
+.It Ar ecn
+Enables ECN (Explicit Congestion Notification) on this queue.
+ECN implies RED.
+.El
+.Pp
+The
+.Ar cbq
+.Ar scheduler
+supports an additional option:
+.Bl -tag -width Fl
+.It Ar borrow
+The queue can borrow bandwidth from the parent.
+.El
+.Pp
+The
+.Ar hfsc
+.Ar scheduler
+supports some additional options:
+.Bl -tag -width Fl
+.It Ar realtime <sc>
+The minimum required bandwidth for the queue.
+.It Ar upperlimit <sc>
+The maximum allowed bandwidth for the queue.
+.It Ar linkshare <sc>
+The bandwidth share of a backlogged queue.
+.El
+.Pp
+<sc> is an acronym for
+.Ar service curve .
+.Pp
+The format for service curve specifications is
+.Ar ( m1 , d , m2 ) .
+.Ar m2
+controls the bandwidth assigned to the queue.
+.Ar m1
+and
+.Ar d
+are optional and can be used to control the initial bandwidth assignment.
+For the first
+.Ar d
+milliseconds the queue gets the bandwidth given as
+.Ar m1 ,
+afterwards the value given in
+.Ar m2 .
+.Pp
+Furthermore, with
+.Ar cbq
+and
+.Ar hfsc ,
+child queues can be specified as in an
+.Ar altq
+declaration, thus building a tree of queues using a part of
+their parent's bandwidth.
+.Pp
+Packets can be assigned to queues based on filter rules by using the
+.Ar queue
+keyword.
+Normally only one
+.Ar queue
+is specified; when a second one is specified it will instead be used for
+packets which have a
+.Em TOS
+of
+.Em lowdelay
+and for TCP ACKs with no data payload.
+.Pp
+To continue the previous example, the examples below would specify the
+four referenced
+queues, plus a few child queues.
+Interactive
+.Xr ssh 1
+sessions get priority over bulk transfers like
+.Xr scp 1
+and
+.Xr sftp 1 .
+The queues may then be referenced by filtering rules (see
+.Sx PACKET FILTERING
+below).
+.Bd -literal
+queue std bandwidth 10% cbq(default)
+queue http bandwidth 60% priority 2 cbq(borrow red) \e
+      { employees, developers }
+queue  developers bandwidth 75% cbq(borrow)
+queue  employees bandwidth 15%
+queue mail bandwidth 10% priority 0 cbq(borrow ecn)
+queue ssh bandwidth 20% cbq(borrow) { ssh_interactive, ssh_bulk }
+queue  ssh_interactive priority 7
+queue  ssh_bulk priority 0
+
+block return out on dc0 inet all queue std
+pass out on dc0 inet proto tcp from $developerhosts to any port 80 \e
+      keep state queue developers
+pass out on dc0 inet proto tcp from $employeehosts to any port 80 \e
+      keep state queue employees
+pass out on dc0 inet proto tcp from any to any port 22 \e
+      keep state queue(ssh_bulk, ssh_interactive)
+pass out on dc0 inet proto tcp from any to any port 25 \e
+      keep state queue mail
+.Ed
+.Sh TRANSLATION
+Translation rules modify either the source or destination address of the
+packets associated with a stateful connection.
+A stateful connection is automatically created to track packets matching
+such a rule as long as they are not blocked by the filtering section of
+.Nm pf.conf .
+The translation engine modifies the specified address and/or port in the
+packet, recalculates IP, TCP and UDP checksums as necessary, and passes it to
+the packet filter for evaluation.
+.Pp
+Since translation occurs before filtering the filter
+engine will see packets as they look after any
+addresses and ports have been translated. Filter rules
+will therefore have to filter based on the translated
+address and port number.
+Packets that match a translation rule are only automatically passed if
+the
+.Ar pass
+modifier is given, otherwise they are
+still subject to
+.Ar block
+and
+.Ar pass
+rules.
+.Pp
+The state entry created permits
+.Xr pf 4
+to keep track of the original address for traffic associated with that state
+and correctly direct return traffic for that connection.
+.Pp
+Various types of translation are possible with pf:
+.Bl -tag -width xxxx
+.It Ar binat
+A
+.Ar binat
+rule specifies a bidirectional mapping between an external IP netblock
+and an internal IP netblock.
+.It Ar nat
+A
+.Ar nat
+rule specifies that IP addresses are to be changed as the packet
+traverses the given interface.
+This technique allows one or more IP addresses
+on the translating host to support network traffic for a larger range of
+machines on an "inside" network.
+Although in theory any IP address can be used on the inside, it is strongly
+recommended that one of the address ranges defined by RFC 1918 be used.
+These netblocks are:
+.Bd -literal
+10.0.0.0 - 10.255.255.255 (all of net 10, i.e., 10/8)
+172.16.0.0 - 172.31.255.255 (i.e., 172.16/12)
+192.168.0.0 - 192.168.255.255 (i.e., 192.168/16)
+.Ed
+.It Pa rdr
+The packet is redirected to another destination and possibly a
+different port.
+.Ar rdr
+rules can optionally specify port ranges instead of single ports.
+rdr ... port 2000:2999 -> ... port 4000
+redirects ports 2000 to 2999 (inclusive) to port 4000.
+rdr ... port 2000:2999 -> ... port 4000:*
+redirects port 2000 to 4000, 2001 to 4001, ..., 2999 to 4999.
+.El
+.Pp
+In addition to modifying the address, some translation rules may modify
+source or destination ports for
+.Xr tcp 4
+or
+.Xr udp 4
+connections; implicitly in the case of
+.Ar nat
+rules and explicitly in the case of
+.Ar rdr
+rules.
+Port numbers are never translated with a
+.Ar binat
+rule.
+.Pp
+For each packet processed by the translator, the translation rules are
+evaluated in sequential order, from first to last.
+The first matching rule decides what action is taken.
+.Pp
+The
+.Ar no
+option prefixed to a translation rule causes packets to remain untranslated,
+much in the same way as
+.Ar drop quick
+works in the packet filter (see below).
+If no rule matches the packet it is passed to the filter engine unmodified.
+.Pp
+Translation rules apply only to packets that pass through
+the specified interface, and if no interface is specified,
+translation is applied to packets on all interfaces.
+For instance, redirecting port 80 on an external interface to an internal
+web server will only work for connections originating from the outside.
+Connections to the address of the external interface from local hosts will
+not be redirected, since such packets do not actually pass through the
+external interface.
+Redirections cannot reflect packets back through the interface they arrive
+on, they can only be redirected to hosts connected to different interfaces
+or to the firewall itself.
+.Pp
+Note that redirecting external incoming connections to the loopback
+address, as in
+.Bd -literal -offset indent
+rdr on ne3 inet proto tcp to port 8025 -> 127.0.0.1 port 25
+.Ed
+.Pp
+will effectively allow an external host to connect to daemons
+bound solely to the loopback address, circumventing the traditional
+blocking of such connections on a real interface.
+Unless this effect is desired, any of the local non-loopback addresses
+should be used as redirection target instead, which allows external
+connections only to daemons bound to this address or not bound to
+any address.
+.Pp
+See
+.Sx TRANSLATION EXAMPLES
+below.
+.Sh PACKET FILTERING
+.Xr pf 4
+has the ability to
+.Ar block
+and
+.Ar pass
+packets based on attributes of their layer 3 (see
+.Xr ip 4
+and
+.Xr ip6 4 )
+and layer 4 (see
+.Xr icmp 4 ,
+.Xr icmp6 4 ,
+.Xr tcp 4 ,
+.Xr udp 4 )
+headers.
+In addition, packets may also be
+assigned to queues for the purpose of bandwidth control.
+.Pp
+For each packet processed by the packet filter, the filter rules are
+evaluated in sequential order, from first to last.
+The last matching rule decides what action is taken.
+.Pp
+The following actions can be used in the filter:
+.Bl -tag -width xxxx
+.It Ar block
+The packet is blocked.
+There are a number of ways in which a
+.Ar block
+rule can behave when blocking a packet.
+The default behaviour is to
+.Ar drop
+packets silently, however this can be overridden or made
+explicit either globally, by setting the
+.Ar block-policy
+option, or on a per-rule basis with one of the following options:
+.Pp
+.Bl -tag -width xxxx -compact
+.It Ar drop
+The packet is silently dropped.
+.It Ar return-rst
+This applies only to
+.Xr tcp 4
+packets, and issues a TCP RST which closes the
+connection.
+.It Ar return-icmp
+.It Ar return-icmp6
+This causes ICMP messages to be returned for packets which match the rule.
+By default this is an ICMP UNREACHABLE message, however this
+can be overridden by specifying a message as a code or number.
+.It Ar return
+This causes a TCP RST to be returned for
+.Xr tcp 4
+packets and an ICMP UNREACHABLE for UDP and other packets.
+.El
+.Pp
+Options returning packets have no effect if
+.Xr pf 4
+operates on a
+.Xr bridge 4 .
+.It Ar pass
+The packet is passed.
+.El
+.Pp
+If no rule matches the packet, the default action is
+.Ar pass .
+.Pp
+To block everything by default and only pass packets
+that match explicit rules, one uses
+.Bd -literal -offset indent
+block all
+.Ed
+.Pp
+as the first filter rule.
+.Pp
+See
+.Sx FILTER EXAMPLES
+below.
+.Sh PARAMETERS
+The rule parameters specify the packets to which a rule applies.
+A packet always comes in on, or goes out through, one interface.
+Most parameters are optional.
+If a parameter is specified, the rule only applies to packets with
+matching attributes.
+Certain parameters can be expressed as lists, in which case
+.Xr pfctl 8
+generates all needed rule combinations.
+.Bl -tag -width xxxx
+.It Ar in No or Ar out
+This rule applies to incoming or outgoing packets.
+If neither
+.Ar in
+nor
+.Ar out
+are specified, the rule will match packets in both directions.
+.It Ar log
+In addition to the action specified, a log message is generated.
+All packets for that connection are logged, unless the
+.Ar keep state
+or
+.Ar modulate state
+options are specified, in which case only the
+packet that establishes the state is logged.
+(See
+.Ar keep state
+and
+.Ar modulate state
+below).
+The logged packets are sent to the
+.Xr pflog 4
+interface.
+This interface is monitored by the
+.Xr pflogd 8
+logging daemon, which dumps the logged packets to the file
+.Pa /var/log/pflog
+in
+.Xr pcap 3
+binary format.
+.It Ar log-all
+Used with
+.Ar keep state
+or
+.Ar modulate state
+rules to force logging of all packets for a connection.
+As with
+.Ar log ,
+packets are logged to
+.Xr pflog 4 .
+.It Ar quick
+If a packet matches a rule which has the
+.Ar quick
+option set, this rule
+is considered the last matching rule, and evaluation of subsequent rules
+is skipped.
+.It Ar on <interface>
+This rule applies only to packets coming in on, or going out through, this
+particular interface.
+.It Ar <af>
+This rule applies only to packets of this address family.
+Supported values are
+.Ar inet
+and
+.Ar inet6 .
+.It Ar proto <protocol>
+This rule applies only to packets of this protocol.
+Common protocols are
+.Xr icmp 4 ,
+.Xr icmp6 4 ,
+.Xr tcp 4 ,
+and
+.Xr udp 4 .
+For a list of all the protocol name to number mappings used by
+.Xr pfctl 8 ,
+see the file
+.Em /etc/protocols .
+.It Xo
+.Ar from <source> port <source> os <source>
+.Ar to <dest> port <dest>
+.Xc
+This rule applies only to packets with the specified source and destination
+addresses and ports.
+.Pp
+Addresses can be specified in CIDR notation (matching netblocks), as
+symbolic host names or interface names, or as any of the following keywords:
+.Pp
+.Bl -tag -width xxxxxxxxxxxx -compact
+.It Ar any
+Any address.
+.It Ar no-route
+Any address which is not currently routable.
+.It Ar <table>
+Any address that matches the given table.
+.El
+.Pp
+Interface names can have modifiers appended:
+.Pp
+.Bl -tag -width xxxxxxxxxxxx -compact
+.It Ar :network
+Translates to the network(s) attached to the interface.
+.It Ar :broadcast
+Translates to the interface's broadcast address(es).
+.El
+.Pp
+Host name resolution and interface to address translation are done at
+ruleset load-time.
+When the address of an interface (or host name) changes (under DHCP or PPP,
+for instance), the ruleset must be reloaded for the change to be reflected
+in the kernel.
+Surrounding the interface name in parentheses changes this behaviour.
+When the interface name is surrounded by parentheses, the rule is
+automatically updated whenever the interface changes its address.
+The ruleset does not need to be reloaded.
+This is especially useful with
+.Ar nat .
+.Pp
+Ports can be specified either by number or by name.
+For example, port 80 can be specified as
+.Em www .
+For a list of all port name to number mappings used by
+.Xr pfctl 8 ,
+see the file
+.Pa /etc/services .
+.Pp
+Ports and ranges of ports are specified by using these operators:
+.Bd -literal -offset indent
+=	(equal)
+!=	(unequal)
+<	(less than)
+<=	(less than or equal)
+>	(greater than)
+>=	(greater than or equal)
+><	(range)
+<>	(except range)
+.Ed
+.Pp
+>< and <>
+are binary operators (they take two arguments), and the range
+does not include the limits.
+For instance:
+.Bl -tag -width Fl
+.It Ar port 2000 >< 2004
+means
+.Sq all ports > 2000 and < 2004 ,
+hence ports 2001, 2002 and 2003.
+.It Ar port 2000 <> 2004
+means
+.Sq all ports < 2000 or > 2004 ,
+hence ports 1-1999 and 2005-65535.
+.El
+.Pp
+The operating system of the source host can be specified in the case of TCP
+rules with the
+.Ar OS
+modifier.
+See the
+.Sx OPERATING SYSTEM FINGERPRINTING
+section for more information.
+.Pp
+The host, port and OS specifications are optional, as in the following examples:
+.Bd -literal -offset indent
+pass in all
+pass in from any to any
+pass in proto tcp from any port <= 1024 to any
+pass in proto tcp from any to any port 25
+pass in proto tcp from 10.0.0.0/8 port > 1024 \e
+      to ! 10.1.2.3 port != ssh
+pass in proto tcp from any os "OpenBSD" flags S/SA
+.Ed
+.It Ar all
+This is equivalent to "from any to any".
+.It Ar group <group>
+Similar to
+.Ar user ,
+this rule only applies to packets of sockets owned by the specified group.
+.It Ar user <user>
+This rule only applies to packets of sockets owned by the specified user.
+For outgoing connections initiated from the firewall, this is the user
+that opened the connection.
+For incoming connections to the firewall itself, this is the user that
+listens on the destination port.
+For forwarded connections, where the firewall is not a connection endpoint,
+the user and group are
+.Em unknown .
+.Pp
+All packets, both outgoing and incoming, of one connection are associated
+with the same user and group.
+Only TCP and UDP packets can be associated with users; for other protocols
+these parameters are ignored.
+.Pp
+User and group refer to the effective (as opposed to the real) IDs, in
+case the socket is created by a setuid/setgid process.
+User and group IDs are stored when a socket is created;
+when a process creates a listening socket as root (for instance, by
+binding to a privileged port) and subsequently changes to another
+user ID (to drop privileges), the credentials will remain root.
+.Pp
+User and group IDs can be specified as either numbers or names.
+The syntax is similar to the one for ports.
+The value
+.Em unknown
+matches packets of forwarded connections.
+.Em unknown
+can only be used with the operators
+.Cm =
+and
+.Cm != .
+Other constructs like
+.Cm user >= unknown
+are invalid.
+Forwarded packets with unknown user and group ID match only rules
+that explicitly compare against
+.Em unknown
+with the operators
+.Cm =
+or
+.Cm != .
+For instance
+.Cm user >= 0
+does not match forwarded packets.
+The following example allows only selected users to open outgoing
+connections:
+.Bd -literal -offset indent
+block out proto { tcp, udp } all
+pass  out proto { tcp, udp } all \e
+      user { < 1000, dhartmei } keep state
+.Ed
+.It Ar flags <a>/<b> | /<b>
+This rule only applies to TCP packets that have the flags
+.Ar <a>
+set out of set
+.Ar <b> .
+Flags not specified in
+.Ar <b>
+are ignored.
+The flags are: (F)IN, (S)YN, (R)ST, (P)USH, (A)CK, (U)RG, (E)CE, and C(W)R.
+.Bl -tag -width Fl
+.It Ar flags S/S
+Flag SYN is set.
+The other flags are ignored.
+.It Ar flags S/SA
+Out of SYN and ACK, exactly SYN may be set.
+SYN, SYN+PSH and SYN+RST match, but SYN+ACK, ACK and ACK+RST do not.
+This is more restrictive than the previous example.
+.It Ar flags /SFRA
+If the first set is not specified, it defaults to none.
+All of SYN, FIN, RST and ACK must be unset.
+.El
+.It Ar icmp-type <type> code <code>
+.It Ar icmp6-type <type> code <code>
+This rule only applies to ICMP or ICMPv6 packets with the specified type
+and code.
+This parameter is only valid for rules that cover protocols ICMP or
+ICMP6.
+The protocol and the ICMP type indicator (icmp-type or icmp6-type)
+must match.
+.It Ar allow-opts
+By default, packets which contain IP options are blocked.
+When
+.Ar allow-opts
+is specified for a
+.Ar pass
+rule, packets that pass the filter based on that rule (last matching)
+do so even if they contain IP options.
+For packets that match state, the rule that initially created the
+state is used.
+The implicit
+.Ar pass
+rule that is used when a packet does not match any rules does not
+allow IP options.
+.It Ar label <string>
+Adds a label (name) to the rule, which can be used to identify the rule.
+For instance,
+pfctl -s labels
+shows per-rule statistics for rules that have labels.
+.Pp
+The following macros can be used in labels:
+.Pp
+.Bl -tag -width $srcaddr -compact -offset indent
+.It Ar $if
+The interface.
+.It Ar $srcaddr
+The source IP address.
+.It Ar $dstaddr
+The destination IP address.
+.It Ar $srcport
+The source port specification.
+.It Ar $dstport
+The destination port specification.
+.It Ar $proto
+The protocol name.
+.It Ar $nr
+The rule number.
+.El
+.Pp
+For example:
+.Bd -literal -offset indent
+ips = \&"{ 1.2.3.4, 1.2.3.5 }\&"
+pass in proto tcp from any to $ips \e
+      port > 1023 label \&"$dstaddr:$dstport\&"
+.Ed
+.Pp
+expands to
+.Bd -literal -offset indent
+pass in inet proto tcp from any to 1.2.3.4 \e
+      port > 1023 label \&"1.2.3.4:>1023\&"
+pass in inet proto tcp from any to 1.2.3.5 \e
+      port > 1023 label \&"1.2.3.5:>1023\&"
+.Ed
+.Pp
+The macro expansion for the
+.Ar label
+directive occurs only at configuration file parse time, not during runtime.
+.It Ar queue <queue> | ( <queue> , <queue> )
+Packets matching this rule will be assigned to the specified queue.
+If two queues are given, packets which have a
+.Em tos
+of
+.Em lowdelay
+and TCP ACKs with no data payload will be assigned to the second one.
+See
+.Sx QUEUEING
+for setup details.
+.Pp
+For example:
+.Bd -literal -offset indent
+pass in proto tcp to port 25 queue mail
+pass in proto tcp to port 22 queue(ssh_bulk, ssh_prio)
+.Ed
+.It Ar tag <string>
+Packets matching this rule will be tagged with the
+specified string.
+The tag acts as an internal marker that can be used to
+identify these packets later on.
+This can be used, for example, to provide trust between
+interfaces and to determine if packets have been
+processed by translation rules.
+Tags are
+.Qq sticky ,
+meaning that the packet will be tagged even if the rule
+is not the last matching rule.
+Further matching rules can replace the tag with a
+new one but will not remove a previously applied tag.
+A packet is only ever assigned one tag at a time.
+.Ar pass
+rules that use the
+.Ar tag
+keyword must also use
+.Ar keep state .
+Packet tagging can be done during
+.Ar nat ,
+.Ar rdr ,
+or
+.Ar binat
+rules in addition to filter rules.
+.It Ar tagged <string>
+Used with filter rules to specify that packets must already
+be tagged with the given tag in order to match the rule.
+Inverse tag matching can also be done
+by specifying the
+.Cm !\&
+operator before the
+.Ar tagged
+keyword.
+.El
+.Sh ROUTING
+If a packet matches a rule with a route option set, the packet filter will
+route the packet according to the type of route option.
+When such a rule creates state, the route option is also applied to all
+packets matching the same connection.
+.Bl -tag -width xxxx
+.It Ar fastroute
+The
+.Ar fastroute
+option does a normal route lookup to find the next hop for the packet.
+.It Ar route-to
+The
+.Ar route-to
+option routes the packet to the specified interface with an optional address
+for the next hop.
+When a
+.Ar route-to
+rule creates state, only packets that pass in the same direction as the
+filter rule specifies will be routed in this way.
+Packets passing in the opposite direction (replies) are not affected
+and are routed normally.
+.It Ar reply-to
+The
+.Ar reply-to
+option is similar to
+.Ar route-to ,
+but routes packets that pass in the opposite direction (replies) to the
+specified interface.
+Opposite direction is only defined in the context of a state entry, and
+.Ar route-to
+is useful only in rules that create state.
+It can be used on systems with multiple external connections to
+route all outgoing packets of a connection through the interface
+the incoming connection arrived through (symmetric routing enforcement).
+.It Ar dup-to
+The
+.Ar dup-to
+option creates a duplicate of the packet and routes it like
+.Ar route-to .
+The original packet gets routed as it normally would.
+.El
+.Sh POOL OPTIONS
+For
+.Ar nat
+and
+.Ar rdr
+rules, (as well as for the
+.Ar route-to ,
+.Ar reply-to
+and
+.Ar dup-to
+rule options) for which there is a single redirection address which has a
+subnet mask smaller than 32 for IPv4 or 128 for IPv6 (more than one IP
+address), a variety of different methods for assigning this address can be
+used:
+.Bl -tag -width xxxx
+.It Ar bitmask
+The
+.Ar bitmask
+option applies the network portion of the redirection address to the address
+to be modified (source with
+.Ar nat ,
+destination with
+.Ar rdr ) .
+.It Ar random
+The
+.Ar random
+option selects an address at random within the defined block of addresses.
+.It Ar source-hash
+The
+.Ar source-hash
+option uses a hash of the source address to determine the redirection address,
+ensuring that the redirection address is always the same for a given source.
+An optional key can be specified after this keyword either in hex or as a
+string; by default
+.Xr pfctl 8
+randomly generates a key for source-hash every time the
+ruleset is reloaded.
+.It Ar round-robin
+The
+.Ar round-robin
+option loops through the redirection address(es).
+.Pp
+When more than one redirection address is specified,
+.Ar round-robin
+is the only permitted pool type.
+.It Ar static-port
+With
+.Ar nat
+rules, the
+.Ar static-port
+option prevents
+.Xr pf 4
+from modifying the source port on TCP and UDP packets.
+.El
+.Sh STATEFUL INSPECTION
+.Xr pf 4
+is a stateful packet filter, which means it can track the state of
+a connection.
+Instead of passing all traffic to port 25, for instance, it is possible
+to pass only the initial packet, and then begin to keep state.
+Subsequent traffic will flow because the filter is aware of the connection.
+.Pp
+If a packet matches a
+.Ar pass ... keep state
+rule, the filter creates a state for this connection and automatically
+lets pass all subsequent packets of that connection.
+.Pp
+Before any rules are evaluated, the filter checks whether the packet
+matches any state.
+If it does, the packet is passed without evaluation of any rules.
+.Pp
+States are removed after the connection is closed or has timed out.
+.Pp
+This has several advantages.
+Comparing a packet to a state involves checking its sequence numbers.
+If the sequence numbers are outside the narrow windows of expected
+values, the packet is dropped.
+This prevents spoofing attacks, such as when an attacker sends packets with
+a fake source address/port but does not know the connection's sequence
+numbers.
+.Pp
+Also, looking up states is usually faster than evaluating rules.
+If there are 50 rules, all of them are evaluated sequentially in O(n).
+Even with 50000 states, only 16 comparisons are needed to match a
+state, since states are stored in a binary search tree that allows
+searches in O(log2 n).
+.Pp
+For instance:
+.Bd -literal -offset indent
+block all
+pass out proto tcp from any to any flags S/SA keep state
+pass in  proto tcp from any to any port 25 flags S/SA keep state
+.Ed
+.Pp
+This ruleset blocks everything by default.
+Only outgoing connections and incoming connections to port 25 are allowed.
+The initial packet of each connection has the SYN
+flag set, will be passed and creates state.
+All further packets of these connections are passed if they match a state.
+.Pp
+Specifying
+.Ar flags S/SA
+restricts state creation to the initial SYN
+packet of the TCP handshake.
+One can also be less restrictive, and allow state creation from
+intermediate
+.Pq non-SYN
+packets.
+This will cause
+.Xr pf 4
+to synchronize to existing connections, for instance
+if one flushes the state table.
+.Pp
+For UDP, which is stateless by nature,
+.Ar keep state
+will create state as well.
+UDP packets are matched to states using only host addresses and ports.
+.Pp
+ICMP messages fall into two categories: ICMP error messages, which always
+refer to a TCP or UDP packet, are matched against the referred to connection.
+If one keeps state on a TCP connection, and an ICMP source quench message
+referring to this TCP connection arrives, it will be matched to the right
+state and get passed.
+.Pp
+For ICMP queries,
+.Ar keep state
+creates an ICMP state, and
+.Xr pf 4
+knows how to match ICMP replies to states.
+For example,
+.Bd -literal -offset indent
+pass out inet proto icmp all icmp-type echoreq keep state
+.Ed
+.Pp
+allows echo requests (such as those created by
+.Xr ping 8 )
+out, creates state, and matches incoming echo replies correctly to states.
+.Pp
+Note:
+.Ar nat , binat No and Ar rdr
+rules implicitly create state for connections.
+.Sh STATE MODULATION
+Much of the security derived from TCP is attributable to how well the
+initial sequence numbers (ISNs) are chosen.
+Some popular stack implementations choose
+.Em very
+poor ISNs and thus are normally susceptible to ISN prediction exploits.
+By applying a
+.Ar modulate state
+rule to a TCP connection,
+.Xr pf 4
+will create a high quality random sequence number for each connection
+endpoint.
+.Pp
+The
+.Ar modulate state
+directive implicitly keeps state on the rule and is
+only applicable to TCP connections.
+.Pp
+For instance:
+.Bd -literal -offset indent
+block all
+pass out proto tcp from any to any modulate state
+pass in  proto tcp from any to any port 25 flags S/SA modulate state
+.Ed
+.Pp
+There are two caveats associated with state modulation:
+A
+.Ar modulate state
+rule can not be applied to a pre-existing but unmodulated connection.
+Such an application would desynchronize TCP's strict
+sequencing between the two endpoints.
+Instead,
+.Xr pf 4
+will treat the
+.Ar modulate state
+modifier as a
+.Ar keep state
+modifier and the pre-existing connection will be inferred without
+the protection conferred by modulation.
+.Pp
+The other caveat affects currently modulated states when the state table
+is lost (firewall reboot, flushing the state table, etc...).
+.Xr pf 4
+will not be able to infer a connection again after the state table flushes
+the connection's modulator.
+When the state is lost, the connection may be left dangling until the
+respective endpoints time out the connection.
+It is possible on a fast local network for the endpoints to start an ACK
+storm while trying to resynchronize after the loss of the modulator.
+Using a
+.Ar flags S/SA
+modifier on
+.Ar modulate state
+rules between fast networks is suggested to prevent ACK storms.
+.Sh SYN PROXY
+By default,
+.Xr pf 4
+passes packets that are part of a
+.Xr tcp 4
+handshake between the endpoints.
+The
+.Ar synproxy state
+option can be used to cause
+.Xr pf 4
+itself to complete the handshake with the active endpoint, perform a handshake
+with the passive endpoint, and then forward packets between the endpoints.
+.Pp
+No packets are sent to the passive endpoint before the active endpoint has
+completed the handshake, hence so-called SYN floods with spoofed source
+addresses will not reach the passive endpoint, as the sender can't complete the
+handshake.
+.Pp
+The proxy is transparent to both endpoints, they each see a single
+connection from/to the other endpoint.
+.Xr pf 4
+choses random initial sequence numbers for both handshakes.
+Once the handshakes are completed, the sequence number modulators
+(see previous section) are used to translate further packets of the
+connection.
+Hence,
+.Ar synproxy state
+includes
+.Ar modulate state
+and
+.Ar keep state .
+.Pp
+Rules with
+.Ar synproxy
+will not work if
+.Xr pf 4
+operates on a
+.Xr bridge 4 .
+.Pp
+Example:
+.Bd -literal -offset indent
+pass in proto tcp from any to any port www flags S/SA synproxy state
+.Ed
+.Sh STATEFUL TRACKING OPTIONS
+All three of
+.Ar keep state ,
+.Ar modulate state
+and
+.Ar synproxy state
+support the following options:
+.Pp
+.Bl -tag -width xxxx -compact
+.It Ar max <number>
+Limits the number of concurrent states the rule may create.
+When this limit is reached, further packets matching the rule that would
+create state are dropped, until existing states time out.
+.It Ar <timeout> <seconds>
+Changes the timeout values used for states created by this rule.
+For a list of all valid timeout names, see
+.Sx OPTIONS
+above.
+.Pp
+Multiple options can be specified, separated by commas:
+.Bd -literal
+pass in proto tcp from any to any \e
+      port www flags S/SA keep state \e
+      (max 100, tcp.established 60, tcp.closing 5)
+.Ed
+.El
+.Sh OPERATING SYSTEM FINGERPRINTING
+Passive OS Fingerprinting is a mechanism to inspect nuances of a TCP
+connection's initial SYN packet and guess at the host's operating system.
+Unfortunately these nuances are easily spoofed by an attacker so the
+fingerprint is not useful in making security decisions.
+But the fingerprint is typically accurate enough to make policy decisions
+upon.
+.Pp
+The fingerprints may be specified by operating system class, by
+version, or by subtype/patchlevel.
+The class of an operating system is typically the vender or genre
+and would be OpenBSD for the
+.Xr pf 4
+firewall itself.
+The version of the oldest available OpenBSD release on the main ftp site
+would be 2.6 and the fingerprint would be written
+.Pp
+.Dl \&"OpenBSD 2.6\&"
+.Pp
+The subtype of an operating system is typically used to describe the
+patchlevel if that patch led to changes in the TCP stack behavior.
+In the case of OpenBSD, the only subtype is for a fingerprint that was
+normalized by the
+.Ar no-df
+scrub option and would be specified as
+.Pp
+.Dl \&"OpenBSD 3.3 no-df\&"
+.Pp
+Fingerprints for most popular operating systems are provided by
+.Xr pf.os 5 .
+Once
+.Xr pf 4
+is running, a complete list of known operating system fingerprints may
+be listed by running:
+.Pp
+.Dl # pfctl -so
+.Pp
+Filter rules can enforce policy at any level of operating system specification
+assuming a fingerprint is present.
+Policy could limit traffic to approved operating systems or even ban traffic
+from hosts that aren't at the latest service pack.
+.Pp
+The
+.Ar unknown
+class can also be used as the fingerprint which will match packets for
+which no operating system fingerprint is known.
+.Pp
+Examples:
+.Bd -literal -offset indent
+pass  out proto tcp from any os OpenBSD keep state
+block out proto tcp from any os Doors
+block out proto tcp from any os "Doors PT"
+block out proto tcp from any os "Doors PT SP3"
+block out from any os "unknown"
+pass on lo0 proto tcp from any os "OpenBSD 3.3 lo0" keep state
+.Ed
+.Pp
+Operating system fingerprinting is limited only to the TCP SYN packet.
+This means that it will not work on other protocols and will not match
+a currently established connection.
+.Pp
+Caveat: operating system fingerprints are occasionally wrong.
+There are three problems: an attacker can trivially craft his packets to
+appear as any operating system he chooses;
+an operating system patch could change the stack behavior and no fingerprints
+will match it until the database is updated;
+and multiple operating systems may have the same fingerprint.
+.Sh BLOCKING SPOOFED TRAFFIC
+"Spoofing" is the faking of IP addresses, typically for malicious
+purposes.
+The
+.Ar antispoof
+directive expands to a set of filter rules which will block all
+traffic with a source IP from the network(s) directly connected
+to the specified interface(s) from entering the system through
+any other interface.
+.Pp
+For example, the line
+.Bd -literal -offset indent
+antispoof for lo0
+.Ed
+.Pp
+expands to
+.Bd -literal -offset indent
+block drop in on ! lo0 inet from 127.0.0.1/8 to any
+block drop in on ! lo0 inet6 from ::1 to any
+.Ed
+.Pp
+For non-loopback interfaces, there are additional rules to block incoming
+packets with a source IP address identical to the interface's IP(s).
+For example, assuming the interface wi0 had an IP address of 10.0.0.1 and a
+netmask of 255.255.255.0,
+the line
+.Bd -literal -offset indent
+antispoof for wi0 inet
+.Ed
+.Pp
+expands to
+.Bd -literal -offset indent
+block drop in on ! wi0 inet from 10.0.0.0/24 to any
+block drop in inet from 10.0.0.1 to any
+.Ed
+.Pp
+Caveat: Rules created by the
+.Ar antispoof
+directive interfere with packets sent over loopback interfaces
+to local addresses.
+One should pass these explicitly.
+.Sh FRAGMENT HANDLING
+The size of IP datagrams (packets) can be significantly larger than the
+the maximum transmission unit (MTU) of the network.
+In cases when it is necessary or more efficient to send such large packets,
+the large packet will be fragmented into many smaller packets that will each
+fit onto the wire.
+Unfortunately for a firewalling device, only the first logical fragment will
+contain the necessary header information for the subprotocol that allows
+.Xr pf 4
+to filter on things such as TCP ports or to perform NAT.
+.Pp
+Besides the use of
+.Ar scrub
+rules as described in
+.Sx TRAFFIC NORMALIZATION
+above, there are three options for handling fragments in the packet filter.
+.Pp
+One alternative is to filter individual fragments with filter rules.
+If no
+.Ar scrub
+rule applies to a fragment, it is passed to the filter.
+Filter rules with matching IP header parameters decide whether the
+fragment is passed or blocked, in the same way as complete packets
+are filtered.
+Without reassembly, fragments can only be filtered based on IP header
+fields (source/destination address, protocol), since subprotocol header
+fields are not available (TCP/UDP port numbers, ICMP code/type).
+The
+.Ar fragment
+option can be used to restrict filter rules to apply only to
+fragments, but not complete packets.
+Filter rules without the
+.Ar fragment
+option still apply to fragments, if they only specify IP header fields.
+For instance, the rule
+.Bd -literal -offset indent
+pass in proto tcp from any to any port 80
+.Ed
+.Pp
+never applies to a fragment, even if the fragment is part of a TCP
+packet with destination port 80, because without reassembly this information
+is not available for each fragment.
+This also means that fragments cannot create new or match existing
+state table entries, which makes stateful filtering and address
+translation (NAT, redirection) for fragments impossible.
+.Pp
+It's also possible to reassemble only certain fragments by specifying
+source or destination addresses or protocols as parameters in
+.Ar scrub
+rules.
+.Pp
+In most cases, the benefits of reassembly outweigh the additional
+memory cost, and it's recommended to use
+.Ar scrub
+rules to reassemble
+all fragments via the
+.Ar fragment reassemble
+modifier.
+.Pp
+The memory allocated for fragment caching can be limited using
+.Xr pfctl 8 .
+Once this limit is reached, fragments that would have to be cached
+are dropped until other entries time out.
+The timeout value can also be adjusted.
+.Pp
+Currently, only IPv4 fragments are supported and IPv6 fragments
+are blocked unconditionally.
+.Sh ANCHORS AND NAMED RULESETS
+Besides the main ruleset,
+.Xr pfctl 8
+can load named rulesets into
+.Ar anchor
+attachment points.
+An
+.Ar anchor
+contains a list of named rulesets.
+An
+.Ar anchor
+has a name which specifies where
+.Xr pfctl 8
+can be used to attach sub-rulesets.
+A named ruleset contains filter and translation rules, like the
+main ruleset.
+The main ruleset can reference
+.Ar anchor
+attachment points
+using the following kinds
+of rules:
+.Bl -tag -width xxxx
+.It Ar nat-anchor <name>
+Evaluates the
+.Ar nat
+rules of all named rulesets in the specified
+.Ar anchor .
+.It Ar rdr-anchor <name>
+Evaluates the
+.Ar rdr
+rules of all named rulesets in the specified
+.Ar anchor .
+.It Ar binat-anchor <name>
+Evaluates the
+.Ar binat
+rules of all named rulesets in the specified
+.Ar anchor .
+.It Ar anchor <name>
+Evaluates the filter rules of all named rulesets in the specified
+.Ar anchor .
+.It Ar load anchor <name>:<ruleset> from <file>
+Loads the rules from the specified file into the named
+ruleset
+.Ar <ruleset>
+attached to the anchor
+.Ar <name> .
+.El
+.Pp
+When evaluation of the main ruleset reaches an
+.Ar anchor
+rule,
+.Xr pf 4
+will proceed to evaluate all rules specified in the
+named rulesets attached to that
+.Ar anchor .
+.Pp
+Matching filter rules in named rulesets with the
+.Ar quick
+option and matching translation rules are final and abort the
+evaluation of both the rules in the
+.Ar anchor
+and the main ruleset.
+.Pp
+Only the main ruleset can contain
+.Ar anchor
+rules.
+.Pp
+When an
+.Ar anchor
+contains more than one named ruleset, they are evaluated
+in the alphabetical order of their names.
+.Pp
+Rules may contain
+.Ar anchor
+attachment points which do not contain any rules when the main ruleset
+is loaded, and later such named rulesets can be manipulated through
+.Xr pfctl 8
+without reloading the main ruleset.
+For example,
+.Bd -literal -offset indent
+ext_if = \&"kue0\&"
+block on $ext_if all
+anchor spam
+pass out on $ext_if all keep state
+pass in on $ext_if proto tcp from any \e
+      to $ext_if port smtp keep state
+.Ed
+.Pp
+blocks all packets on the external interface by default, then evaluates
+all rulesets in the
+.Ar anchor
+named "spam", and finally passes all outgoing connections and
+incoming connections to port 25.
+.Bd -literal -offset indent
+# echo \&"block in quick from 1.2.3.4 to any\&" \&| \e
+      pfctl -a spam:manual -f -
+.Ed
+.Pp
+loads a single ruleset containing a single rule into the
+.Ar anchor ,
+which blocks all packets from a specific address.
+.Pp
+The named ruleset can also be populated by adding a
+.Ar load anchor
+rule after the
+.Ar anchor
+rule:
+.Bd -literal -offset indent
+anchor spam
+load anchor spam:manual from /etc/pf-spam.conf
+.Ed
+.Pp
+When
+.Xr pfctl 8
+loads
+.Nm pf.conf ,
+it will also load all the rules from the file
+.Pa /etc/pf-spam.conf
+into the named ruleset.
+.Pp
+Optionally,
+.Ar anchor
+rules can specify the parameter's
+direction, interface, address family, protocol and source/destination
+address/port
+using the same syntax as filter rules.
+When parameters are used, the
+.Ar anchor
+rule is only evaluated for matching packets.
+This allows conditional evaluation of named rulesets, like:
+.Bd -literal -offset indent
+block on $ext_if all
+anchor spam proto tcp from any to any port smtp
+pass out on $ext_if all keep state
+pass in on $ext_if proto tcp from any to $ext_if port smtp keep state
+.Ed
+.Pp
+The rules inside
+.Ar anchor
+spam are only evaluated for
+.Ar tcp
+packets with destination port 25.
+Hence,
+.Bd -literal -offset indent
+# echo \&"block in quick from 1.2.3.4 to any" \&| \e
+      pfctl -a spam:manual -f -
+.Ed
+.Pp
+will only block connections from 1.2.3.4 to port 25.
+.Sh TRANSLATION EXAMPLES
+This example maps incoming requests on port 80 to port 8080, on
+which a daemon is running (because, for example, it is not run as root,
+and therefore lacks permission to bind to port 80).
+.Bd -literal
+# map daemon on 8080 to appear to be on 80
+rdr on ne3 proto tcp from any to any port 80 -> 127.0.0.1 port 8080
+.Ed
+.Pp
+If the
+.Ar pass
+modifier is given, packets matching the translation rule are passed without
+inspecting the filter rules:
+.Bd -literal
+rdr pass on ne3 proto tcp from any to any port 80 -> 127.0.0.1 port 8080
+.Ed
+.Pp
+In the example below, vlan12 is configured as 192.168.168.1;
+the machine translates all packets coming from 192.168.168.0/24 to 204.92.77.111
+when they are going out any interface except vlan12.
+This has the net effect of making traffic from the 192.168.168.0/24
+network appear as though it is the Internet routable address
+204.92.77.111 to nodes behind any interface on the router except
+for the nodes on vlan12.
+(Thus, 192.168.168.1 can talk to the 192.168.168.0/24 nodes.)
+.Bd -literal
+nat on ! vlan12 from 192.168.168.0/24 to any -> 204.92.77.111
+.Ed
+.Pp
+In the example below, fxp1 is the outside interface; the machine sits between a
+fake internal 144.19.74.* network, and a routable external IP of 204.92.77.100.
+The
+.Ar no nat
+rule excludes protocol AH from being translated.
+.Bd -literal
+# NO NAT
+no nat on fxp1 proto ah from 144.19.74.0/24 to any
+nat on fxp1 from 144.19.74.0/24 to any -> 204.92.77.100
+.Ed
+.Pp
+In the example below, fxp0 is the internal interface.
+Packets bound
+for one specific server, as well as those generated by the sysadmins
+are not proxied; all other connections are.
+.Bd -literal
+# NO RDR
+no rdr on fxp0 proto { tcp, udp } from any to $server port 80
+no rdr on fxp0 proto { tcp, udp } from $sysadmins to any port 80
+rdr on fxp0 proto { tcp, udp } from any to any port 80 -> 127.0.0.1 port 80
+.Ed
+.Pp
+This longer example uses both a NAT and a redirection.
+Interface kue0 is the outside interface, and its external address is
+157.161.48.183.
+Interface fxp0 is the inside interface, and we are running
+.Xr ftp-proxy 8 ,
+listening for outbound ftp sessions captured to port 8021.
+.Bd -literal
+# NAT
+# Translate outgoing packets' source addresses (any protocol).
+# In this case, any address but the gateway's external address is mapped.
+nat on kue0 inet from ! (kue0) to any -> (kue0)
+
+# NAT PROXYING
+# Map outgoing packets' source port to an assigned proxy port instead of
+# an arbitrary port.
+# In this case, proxy outgoing isakmp with port 500 on the gateway.
+nat on kue0 inet proto udp from any port = isakmp to any -> (kue0) \e
+      port 500
+
+# BINAT
+# Translate outgoing packets' source address (any protocol).
+# Translate incoming packets' destination address to an internal machine
+# (bidirectional).
+binat on kue0 from 10.1.2.150 to any -> (kue0)
+
+# RDR
+# Translate incoming packets' destination addresses.
+# As an example, redirect a TCP and UDP port to an internal machine.
+rdr on kue0 inet proto tcp from any to (kue0) port 8080 -> 10.1.2.151 \e
+      port 22
+rdr on kue0 inet proto udp from any to (kue0) port 8080 -> 10.1.2.151 \e
+      port 53
+
+# RDR
+# Translate outgoing ftp control connections to send them to localhost
+# for proxying with ftp-proxy(8) running on port 8021.
+rdr on fxp0 proto tcp from any to any port 21 -> 127.0.0.1 port 8021
+.Ed
+.Pp
+In this example, a NAT gateway is set up to translate internal addresses
+using a pool of public addresses (192.0.2.16/28) and to redirect
+incoming web server connections to a group of web servers on the internal
+network.
+Interface fxp0 is the external interface.
+.Bd -literal
+# NAT LOAD BALANCE
+# Translate outgoing packets' source addresses using an address pool.
+# A given source address is always translated to the same pool address by
+# using the source-hash keyword.
+nat on fxp0 inet from any to any -> 192.0.2.16/28 source-hash
+
+# RDR ROUND ROBIN
+# Translate incoming web server connections to a group of web servers on
+# the internal network.
+rdr on fxp0 proto tcp from any to any port 80 \e
+      -> { 10.1.2.155, 10.1.2.160, 10.1.2.161 } round-robin
+.Ed
+.Sh FILTER EXAMPLES
+.Bd -literal
+# The external interface is kue0
+# (157.161.48.183, the only routable address)
+# and the private network is 10.0.0.0/8, for which we are doing NAT.
+
+# use a macro for the interface name, so it can be changed easily
+ext_if = \&"kue0\&"
+
+# normalize all incoming traffic
+scrub in on $ext_if all fragment reassemble
+
+# block and log everything by default
+block return log on $ext_if all
+
+# block anything coming from source we have no back routes for
+block in from no-route to any
+
+# block and log outgoing packets that do not have our address as source,
+# they are either spoofed or something is misconfigured (NAT disabled,
+# for instance), we want to be nice and do not send out garbage.
+block out log quick on $ext_if from ! 157.161.48.183 to any
+
+# silently drop broadcasts (cable modem noise)
+block in quick on $ext_if from any to 255.255.255.255
+
+# block and log incoming packets from reserved address space and invalid
+# addresses, they are either spoofed or misconfigured, we cannot reply to
+# them anyway (hence, no return-rst).
+block in log quick on $ext_if from { 10.0.0.0/8, 172.16.0.0/12, \e
+      192.168.0.0/16, 255.255.255.255/32 } to any
+
+# ICMP
+
+# pass out/in certain ICMP queries and keep state (ping)
+# state matching is done on host addresses and ICMP id (not type/code),
+# so replies (like 0/0 for 8/0) will match queries
+# ICMP error messages (which always refer to a TCP/UDP packet) are
+# handled by the TCP/UDP states
+pass on $ext_if inet proto icmp all icmp-type 8 code 0 keep state
+
+# UDP
+
+# pass out all UDP connections and keep state
+pass out on $ext_if proto udp all keep state
+
+# pass in certain UDP connections and keep state (DNS)
+pass in on $ext_if proto udp from any to any port domain keep state
+
+# TCP
+
+# pass out all TCP connections and modulate state
+pass out on $ext_if proto tcp all modulate state
+
+# pass in certain TCP connections and keep state (SSH, SMTP, DNS, IDENT)
+pass in on $ext_if proto tcp from any to any port { ssh, smtp, domain, \e
+      auth } flags S/SA keep state
+
+# pass in data mode connections for ftp-proxy running on this host.
+# (see ftp-proxy(8) for details)
+pass in on $ext_if proto tcp from any to 157.161.48.183 port >= 49152 \e
+      flags S/SA keep state
+
+# Do not allow Windows 9x SMTP connections since they are typically
+# a viral worm. Alternately we could limit these OSes to 1 connection each.
+block in on $ext_if proto tcp from any os {"Windows 95", "Windows 98"} \e
+      to any port smtp
+
+# Packet Tagging
+
+# three interfaces: $int_if, $ext_if, and $wifi_if (wireless). NAT is
+# being done on $ext_if for all outgoing packets. tag packets in on
+# $int_if and pass those tagged packets out on $ext_if.  all other
+# outgoing packets (i.e., packets from the wireless network) are only
+# permitted to access port 80.
+
+pass in on $int_if from any to any tag INTNET keep state
+pass in on $wifi_if from any to any keep state
+
+block out on $ext_if from any to any
+pass out quick on $ext_if tagged INTNET keep state
+pass out on $ext_if from any to any port 80 keep state
+
+# tag incoming packets as they are redirected to spamd(8). use the tag
+# to pass those packets through the packet filter.
+
+rdr on $ext_if inet proto tcp from <spammers> to port smtp \e
+	tag SPAMD -> 127.0.0.1 port spamd
+
+block in on $ext_if
+pass in on $ext_if inet proto tcp tagged SPAMD keep state
+.Ed
+.Sh GRAMMAR
+Syntax for
+.Nm
+in BNF:
+.Bd -literal
+line           = ( option | pf-rule | nat-rule | binat-rule | rdr-rule |
+                 antispoof-rule | altq-rule | queue-rule | anchor-rule |
+                 trans-anchors | load-anchors | table-rule )
+
+option         = "set" ( [ "timeout" ( timeout | "{" timeout-list "}" ) ] |
+                 [ "optimization" [ "default" | "normal" |
+                 "high-latency" | "satellite" |
+                 "aggressive" | "conservative" ] ]
+                 [ "limit" ( limit-item | "{" limit-list "}" ) ] |
+                 [ "loginterface" ( interface-name | "none" ) ] |
+                 [ "block-policy" ( "drop" | "return" ) ] |
+                 [ "require-order" ( "yes" | "no" ) ]
+                 [ "fingerprints" filename ] )
+
+pf-rule        = action [ ( "in" | "out" ) ]
+                 [ "log" | "log-all" ] [ "quick" ]
+                 [ "on" ifspec ] [ route ] [ af ] [ protospec ]
+                 hosts [ filteropt-list ]
+
+filteropt-list = filteropt-list filteropt | filteropt
+filteropt      = user | group | flags | icmp-type | icmp6-type | tos |
+                 ( "keep" | "modulate" | "synproxy" ) "state"
+                 [ "(" state-opts ")" ] |
+                 "fragment" | "no-df" | "min-ttl" number |
+                 "max-mss" number | "random-id" | "reassemble tcp" |
+                 fragmentation | "allow-opts" |
+                 "label" string | "tag" string | [ ! ] "tagged" string
+                 "queue" "(" string | ( string [ [ "," ] string ] ) ")"
+
+nat-rule       = [ "no" ] "nat" [ "pass" ] [ "on" ifspec ] [ af ]
+                 [ protospec ] hosts [ "tag" string ]
+                 [ "->" ( redirhost | "{" redirhost-list "}" )
+                 [ portspec ] [ pooltype ] [ "static-port" ] ]
+
+binat-rule     = [ "no" ] "binat" [ "pass" ] [ "on" interface-name ]
+                 [ af ] [ "proto" ( proto-name | proto-number ) ]
+                 "from" address [ "/" mask-bits ] "to" ipspec
+                 [ "tag" string ]
+                 [ "->" address [ "/" mask-bits ] ]
+
+rdr-rule       = [ "no" ] "rdr" [ "pass" ] [ "on" ifspec ] [ af ]
+                 [ protospec ] hosts [ "tag" string ]
+                 [ "->" ( redirhost | "{" redirhost-list "}" )
+                 [ portspec ] [ pooltype ] ]
+
+antispoof-rule = "antispoof" [ "log" ] [ "quick" ]
+                 "for" ( interface-name | "{" interface-list "}" )
+                 [ af ] [ "label" string ]
+
+table-rule     = "table" "<" string ">" [ tableopts-list ]
+tableopts-list = tableopts-list tableopts | tableopts
+tableopts      = "persist" | "const" | "file" string |
+                 "{" [ tableaddr-list ] "}"
+tableaddr-list = tableaddr-list [ "," ] tableaddr-spec | tableaddr-spec
+tableaddr-spec = [ "!" ] tableaddr [ "/" mask-bits ]
+tableaddr      = hostname | ipv4-dotted-quad | ipv6-coloned-hex |
+                 interface-name | "self"
+
+altq-rule      = "altq on" interface-name queueopts-list
+                 "queue" subqueue
+queue-rule     = "queue" string [ "on" interface-name ] queueopts-list
+                 subqueue
+
+anchor-rule    = "anchor" string [ ( "in" | "out" ) ] [ "on" ifspec ]
+                 [ af ] [ "proto" ] [ protospec ] [ hosts ]
+
+trans-anchors  = ( "nat-anchor" | "rdr-anchor" | "binat-anchor" ) string
+                 [ "on" ifspec ] [ af ] [ "proto" ] [ protospec ] [ hosts ]
+
+load-anchor    = "load" anchorname:rulesetname "from" filename
+
+queueopts-list = queueopts-list queueopts | queueopts
+queueopts      = [ "bandwidth" bandwidth-spec ] |
+                 [ "qlimit" number ] | [ "tbrsize" number ] |
+                 [ "priority" number ] | [ schedulers ]
+schedulers     = ( cbq-def | priq-def | hfsc-def )
+bandwidth-spec = "number" ( "b" | "Kb" | "Mb" | "Gb" | "%" )
+
+action         = "pass" | "block" [ "return" ] | "scrub"
+return         = "drop" | "return" | "return-rst" [ "( ttl" number ")" ] |
+                 "return-icmp" [ "(" icmpcode ["," icmp6code ] ")" ] |
+                 "return-icmp6" [ "(" icmp6code ")" ]
+icmpcode       = ( icmp-code-name | icmp-code-number )
+icmp6code      = ( icmp6-code-name | icmp6-code-number )
+
+ifspec         = ( [ "!" ] interface-name ) | "{" interface-list "}"
+interface-list = [ "!" ] interface-name [ [ "," ] interface-list ]
+route          = "fastroute" |
+                 ( "route-to" | "reply-to" | "dup-to" )
+                 ( routehost | "{" routehost-list "}" )
+                 [ pooltype ]
+af             = "inet" | "inet6"
+
+protospec      = "proto" ( proto-name | proto-number |
+                 "{" proto-list "}" )
+proto-list     = ( proto-name | proto-number ) [ [ "," ] proto-list ]
+
+hosts          = "all" |
+                 "from" ( "any" | "no-route" | "self" | host |
+                 "{" host-list "}" ) [ port ] [ os ]
+                 "to"   ( "any" | "no-route" | "self" | host |
+                 "{" host-list "}" ) [ port ]
+
+ipspec         = "any" | host | "{" host-list "}"
+host           = [ "!" ] ( address [ "/" mask-bits ] | "<" string ">" )
+redirhost      = address [ "/" mask-bits ]
+routehost      = ( interface-name [ address [ "/" mask-bits ] ] )
+address        = ( interface-name | "(" interface-name ")" | hostname |
+                 ipv4-dotted-quad | ipv6-coloned-hex )
+host-list      = host [ [ "," ] host-list ]
+redirhost-list = redirhost [ [ "," ] redirhost-list ]
+routehost-list = routehost [ [ "," ] routehost-list ]
+
+port           = "port" ( unary-op | binary-op | "{" op-list "}" )
+portspec       = "port" ( number | name ) [ ":" ( "*" | number | name ) ]
+os             = "os"  ( os-name | "{" os-list "}" )
+user           = "user" ( unary-op | binary-op | "{" op-list "}" )
+group          = "group" ( unary-op | binary-op | "{" op-list "}" )
+
+unary-op       = [ "=" | "!=" | "<" | "<=" | ">" | ">=" ]
+                 ( name | number )
+binary-op      = number ( "<>" | "><" | ":" ) number
+op-list        = ( unary-op | binary-op ) [ [ "," ] op-list ]
+
+os-name        = operating-system-name
+os-list        = os-name [ [ "," ] os-list ]
+
+flags          = "flags" [ flag-set ] "/" flag-set
+flag-set       = [ "F" ] [ "S" ] [ "R" ] [ "P" ] [ "A" ] [ "U" ] [ "E" ]
+                 [ "W" ]
+
+icmp-type      = "icmp-type" ( icmp-type-code | "{" icmp-list "}" )
+icmp6-type     = "icmp6-type" ( icmp-type-code | "{" icmp-list "}" )
+icmp-type-code = ( icmp-type-name | icmp-type-number )
+                 [ "code" ( icmp-code-name | icmp-code-number ) ]
+icmp-list      = icmp-type-code [ [ "," ] icmp-list ]
+
+tos            = "tos" ( "lowdelay" | "throughput" | "reliability" |
+                 [ "0x" ] number )
+
+state-opts     = state-opt [ [ "," ] state-opts ]
+state-opt      = ( "max" number ) | ( timeout )
+
+fragmentation  = [ "fragment reassemble" | "fragment crop" |
+                 "fragment drop-ovl" ]
+
+timeout-list   = timeout [ [ "," ] timeout-list ]
+timeout        = ( "tcp.first" | "tcp.opening" | "tcp.established" |
+                 "tcp.closing" | "tcp.finwait" | "tcp.closed" |
+                 "udp.first" | "udp.single" | "udp.multiple" |
+                 "icmp.first" | "icmp.error" |
+                 "other.first" | "other.single" | "other.multiple" |
+                 "frag" | "interval" |
+                 "adaptive.start" | "adaptive.end" ) number
+
+limit-list     = limit-item [ [ "," ] limit-list ]
+limit-item     = ( "states" | "frags" ) number
+
+pooltype       = ( "bitmask" | "random" |
+                 "source-hash" [ ( hex-key | string-key ) ] |
+                 "round-robin" )
+
+subqueue       = string | "{" queue-list "}"
+queue-list     = string [ [ "," ] string ]
+cbq-def        = "cbq" [ "(" cbq-opt [ [ "," ] cbq-opt ] ")" ]
+priq-def       = "priq" [ "(" priq-opt [ [ "," ] priq-opt ] ")" ]
+hfsc-def       = "hfsc" [ "(" hfsc-opt [ [ "," ] hfsc-opt ] ")" ]
+cbq-opt        = ( "default" | "borrow" | "red" | "ecn" | "rio" )
+priq-opt       = ( "default" | "red" | "ecn" | "rio" )
+hfsc-opt       = ( "default" | "red" | "ecn" | "rio" |
+                 linkshare-sc | realtime-sc | upperlimit-sc )
+linkshare-sc   = "linkshare" sc-spec
+realtime-sc    = "realtime" sc-spec
+upperlimit-sc  = "upperlimit" sc-spec
+sc-spec        = ( bandwidth-spec |
+                 "(" bandwidth-spec number bandwidth-spec ")" )
+.Ed
+.Sh FILES
+.Bl -tag -width "/etc/protocols" -compact
+.It Pa /etc/hosts
+Host name database.
+.It Pa /etc/pf.conf
+Default location of the ruleset file.
+.It Pa /etc/pf.os
+Default location of OS fingerprints.
+.It Pa /etc/protocols
+Protocol name database.
+.It Pa /etc/services
+Service name database.
+.It Pa /usr/share/pf
+Example rulesets.
+.El
+.Sh SEE ALSO
+.Xr icmp 4 ,
+.Xr icmp6 4 ,
+.Xr ip 4 ,
+.Xr ip6 4 ,
+.Xr pf 4 ,
+.Xr tcp 4 ,
+.Xr udp 4 ,
+.Xr hosts 5 ,
+.Xr pf.os 5 ,
+.Xr protocols 5 ,
+.Xr services 5 ,
+.Xr ftp-proxy 8 ,
+.Xr pfctl 8 ,
+.Xr pflogd 8
+.Sh HISTORY
+The
+.Nm
+file format first appeared in
+.Ox 3.0 .
diff --git a/contrib/pf/man/pf.os.5 b/contrib/pf/man/pf.os.5
new file mode 100644
index 0000000..485f69a
--- /dev/null
+++ b/contrib/pf/man/pf.os.5
@@ -0,0 +1,242 @@
+.\"	$OpenBSD: pf.os.5,v 1.4 2003/08/28 09:41:23 jmc Exp $
+.\"
+.\" Copyright (c) 2003 Mike Frantzen <frantzen@w4g.org>
+.\"
+.\" Permission to use, copy, modify, and distribute this software for any
+.\" purpose with or without fee is hereby granted, provided that the above
+.\" copyright notice and this permission notice appear in all copies.
+.\"
+.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+.Dd August 18, 2003
+.Dt PF.OS 5
+.Os
+.Sh NAME
+.Nm pf.os
+.Nd format of the operating system fingerprints file
+.Sh DESCRIPTION
+The
+.Xr pf 4
+firewall and the
+.Xr tcpdump 8
+program can both fingerprint the operating system of hosts that
+originate an IPv4 TCP connection.
+The file consists of newline-separated records, one per fingerprint,
+containing nine colon
+.Pq Ql \&:
+separated fields.
+These fields are as follows:
+.Pp
+.Bl -tag -width Description -offset indent -compact
+.It window
+The TCP window size.
+.It TTL
+The IP time to live.
+.It df
+The presence of the IPv4 don't fragment bit.
+.It packet size
+The size of the initial TCP packet.
+.It TCP options
+An ordered list of the TCP options.
+.It class
+The class of operating system.
+.It version
+The version of the operating system.
+.It subtype
+The subtype of patchlevel of the operating system.
+.It description
+The overall textual description of the operating system, version and subtype.
+.El
+.Pp
+The
+.Ar window
+field corresponds to the th->th_win field in the TCP header and is the
+source host's advertised TCP window size.
+It may be between zero and 65,535 inclusive.
+The window size may be given as a multiple of a constant by prepending
+the size with a percent sign
+.Sq %
+and the value will be used as a modulus.
+Three special values may be used for the window size:
+.Pp
+.Bl -tag -width xxx -offset indent -compact
+.It *
+An asterisk will wildcard the value so any window size will match.
+.It S
+Allow any window size which is a multiple of the maximum segment size (MSS).
+.It T
+Allow any window size which is a multiple of the maximum transmission unit
+(MTU).
+.El
+.Pp
+The
+.Ar ttl
+value is the initial time to live in the IP header.
+The fingerprint code will account for the volatility of the packets's TTL
+as it traverses a network.
+.Pp
+The
+.Ar df
+bit corresponds to the Don't Fragment bit in an IPv4 header.
+It tells intermediate routers not to fragment the packet and is used for
+path MTU discovery.
+It may be either a zero or a one.
+.Pp
+The
+.Ar packet size
+is the literal size of the full IP packet and is a function of all of
+the IP and TCP options.
+.Pp
+The
+.Ar TCP options
+field is an ordered list of the individual TCP options that appear in the
+SYN packet.
+Each option is described by a single character separated by a comma and
+certain ones may include a value.
+The options are:
+.Pp
+.Bl -tag -width Description -offset indent -compact
+.It Mnnn
+maximum segment size (MSS) option.
+The value is the maximum packet size of the network link which may
+include the
+.Sq %
+modulus or match all MSSes with the
+.Sq *
+value.
+.It N
+the NOP option (NO Operation).
+.It T[0]
+the timestamp option.
+Certain operating systems always start with a zero timestamp in which
+case a zero value is added to the option; otherwise no value is appended.
+.It S
+the Selective ACKnowledgement OK (SACKOK) option.
+.It Wnnn
+window scaling option.
+The value is the size of the window scaling which may include the
+.Sq %
+modulus or match all window scalings with the
+.Sq *
+value.
+.El
+.Pp
+No TCP options in the fingerprint may be given with a single dot
+.Sq \&. .
+.Pp
+An example of OpenBSD's TCP options are:
+.Pp
+.Dl M*,N,N,S,N,W0,N,N,T
+.Pp
+The first option
+.Ar M*
+is the MSS option and will match all values.
+The second and third options
+.Ar N
+will match two NOPs.
+The fourth option
+.Ar S
+will match the SACKOK option.
+The fifth
+.Ar N
+will match another NOP.
+The sixth
+.Ar W0
+will match a window scaling option with a zero scaling size.
+The seventh and eighth
+.Ar N
+options will match two NOPs.
+And the ninth and final option
+.Ar T
+will match the timestamp option with any time value.
+.Pp
+The TCP options in a fingerprint will only match packets with the
+exact same TCP options in the same order.
+.Pp
+The
+.Ar class
+field is the class, genre or vender of the operating system.
+.Pp
+The
+.Ar version
+is the version of the operating system.
+It is used to distinguish between different fingerprints of operating
+systems of the same class but different versions.
+.Pp
+The
+.Ar subtype
+is the subtype or patch level of the operating system version.
+It is used to distinguish between different fingerprints of operating
+systems of the same class and same version but slightly different
+patches or tweaking.
+.Pp
+The
+.Ar description
+is a general description of the operating system, its version,
+patchlevel and any further useful details.
+.Sh EXAMPLES
+The fingerprint of a plain
+.Ox 3.3
+host is:
+.Bd -literal
+  16384:64:1:64:M*,N,N,S,N,W0,N,N,T:OpenBSD:3.3::OpenBSD 3.3
+.Ed
+.Pp
+The fingerprint of an
+.Ox 3.3
+host behind a PF scrubbing firewall with a no-df rule would be:
+.Bd -literal
+  16384:64:0:64:M*,N,N,S,N,W0,N,N,T:OpenBSD:3.3:!df:OpenBSD 3.3 scrub no-df
+.Ed
+.Pp
+An absolutely braindead embedded operating system fingerprint could be:
+.Bd -literal
+  65535:255:0:40:.:DUMMY:1.1:p3:Dummy embedded OS v1.1p3
+.Ed
+.Pp
+The
+.Xr tcpdump 8
+output of
+.Bd -literal
+  # tcpdump -s128 -c1 -nv 'tcp[13] == 2'
+  03:13:48.118526 10.0.0.1.3377 > 10.0.0.0.2: S [tcp sum ok] \e
+      534596083:534596083(0) win 57344 <mss 1460> (DF) [tos 0x10] \e
+      (ttl 64, id 11315)
+.Ed
+.Pp
+almost translates into the following fingerprint
+.Bd -literal
+  57344:64:1:44:M1460:	exampleOS:1.0::exampleOS 1.0
+.Ed
+.Pp
+.Xr tcpdump 8
+does not explicitly give the packet length.
+But it can usually be derived by adding the size of the IPv4 header to
+the size of the TCP header to the size of the TCP options.
+The size of both headers is typically twenty each and the usual
+sizes of the TCP options are:
+.Pp
+.Bl -tag -width timestamp -offset indent -compact
+.It mss
+four bytes.
+.It nop
+1 byte.
+.It sackOK
+two bytes.
+.It timestamp
+ten bytes.
+.It wscale
+three bytes.
+.El
+.Pp
+In the above example, the packet size comes out to 44 bytes.
+.Sh SEE ALSO
+.Xr pf 4 ,
+.Xr pf.conf 5 ,
+.Xr pfctl 8 ,
+.Xr tcpdump 8
diff --git a/contrib/pf/man/pflog.4 b/contrib/pf/man/pflog.4
new file mode 100644
index 0000000..eb7a72e
--- /dev/null
+++ b/contrib/pf/man/pflog.4
@@ -0,0 +1,88 @@
+.\"	$OpenBSD: pflog.4,v 1.4 2003/09/22 04:53:15 jmc Exp $
+.\"
+.\" Copyright (c) 2001 Tobias Weingartner
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+.\"
+.Dd December 10, 2001
+.Dt PFLOG 4
+.Os
+.Sh NAME
+.Nm pflog
+.Nd packet filter logging interface
+.Sh SYNOPSIS
+.Sy pseudo-device Nm pflog Em <number>
+.Sh DESCRIPTION
+The
+.Nm pflog
+interface is the interface the packet filter,
+.Xr pf 4 ,
+copies all the packets to which it has been configured to log.
+In this way, all logged packets can easily be monitored in real
+time by invoking
+.Xr tcpdump 8
+on the
+.Nm
+interface.
+.Pp
+Each packet retrieved on this interface has a header associated
+with it of length
+.Dv PFLOG_HDRLEN .
+This header documents the address family, interface name, rule
+number, reason, action, and direction of the packet that was logged.
+This structure, defined in
+.Aq Pa net/if_pflog.h
+looks like
+.Bd -literal -offset indent
+struct pfloghdr {
+	u_int8_t	length;
+	sa_family_t	af;
+	u_int8_t	action;
+	u_int8_t	reason;
+	char		ifname[IFNAMSIZ];
+	char		ruleset[PF_RULESET_NAME_SIZE];
+	u_int32_t	rulenr;
+	u_int32_t	subrulenr;
+	u_int8_t	dir;
+	u_int8_t	pad[3];
+};
+.Ed
+.Sh EXAMPLES
+.Bd -literal -offset indent
+# ifconfig pflog0 up
+# tcpdump -n -e -ttt -i pflog0
+.Ed
+.Sh SEE ALSO
+.Xr inet 4 ,
+.Xr inet6 4 ,
+.Xr netintro 4 ,
+.Xr pf 4 ,
+.Xr ifconfig 8 ,
+.Xr pflogd 8 ,
+.Xr tcpdump 8
+.Sh HISTORY
+The
+.Nm
+device first appeared in
+.Ox 3.0 .
+.\" .Sh BUGS
+.\" Anything here?
diff --git a/contrib/pf/man/pfsync.4 b/contrib/pf/man/pfsync.4
new file mode 100644
index 0000000..21dd7d5
--- /dev/null
+++ b/contrib/pf/man/pfsync.4
@@ -0,0 +1,80 @@
+.\"	$OpenBSD: pfsync.4,v 1.6 2003/06/06 10:29:41 jmc Exp $
+.\"
+.\" Copyright (c) 2002 Michael Shalayeff
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF MIND,
+.\" USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+.\"
+.Dd November 29, 2002
+.Dt PFSYNC 4
+.Os
+.Sh NAME
+.Nm pfsync
+.Nd packet filter states table logging interface
+.Sh SYNOPSIS
+.Sy pseudo-device Nm pfsync
+.Sh DESCRIPTION
+The
+.Nm pfsync
+interface is the interface to the packet filter,
+.Xr pf 4 ,
+exposing all the changes to the state table.
+This allows for both debugging of rulesets and monitoring
+for changes in the table by invoking
+.Xr tcpdump 8
+on the
+.Nm
+interface.
+.Pp
+Each packet retrieved on this interface has a header associated
+with it of length
+.Dv PFSYNC_HDRLEN .
+The header indicates the version of the protocol, address family,
+action taken on the following states and the number of state
+table entries attached in this packet.
+This structure, defined in
+.Aq Pa net/if_pfsync.h
+looks like:
+.Bd -literal -offset indent
+struct pfsync_header {
+	u_int8_t version;
+	u_int8_t af;
+	u_int8_t action;
+	u_int8_t count;
+};
+.Ed
+.Sh EXAMPLES
+.Bd -literal -offset indent
+# ifconfig pfsync0 up
+# tcpdump -s1500 -evtni pfsync0
+.Ed
+.Sh SEE ALSO
+.Xr inet 4 ,
+.Xr inet6 4 ,
+.Xr netintro 4 ,
+.Xr pf 4 ,
+.Xr ifconfig 8 ,
+.Xr tcpdump 8
+.Sh HISTORY
+The
+.Nm
+device first appeared in
+.Ox 3.3 .