diff options
Diffstat (limited to 'usr.sbin/arp')
| -rw-r--r-- | usr.sbin/arp/Makefile | 9 | ||||
| -rw-r--r-- | usr.sbin/arp/Makefile.depend | 19 | ||||
| -rw-r--r-- | usr.sbin/arp/arp.4 | 235 | ||||
| -rw-r--r-- | usr.sbin/arp/arp.8 | 192 | ||||
| -rw-r--r-- | usr.sbin/arp/arp.c | 882 |
5 files changed, 1337 insertions, 0 deletions
diff --git a/usr.sbin/arp/Makefile b/usr.sbin/arp/Makefile new file mode 100644 index 0000000..6ca9dd2 --- /dev/null +++ b/usr.sbin/arp/Makefile @@ -0,0 +1,9 @@ +# @(#)Makefile 8.2 (Berkeley) 4/18/94 +# $FreeBSD$ + +PROG= arp +MAN= arp.4 arp.8 + +WARNS?= 3 + +.include <bsd.prog.mk> diff --git a/usr.sbin/arp/Makefile.depend b/usr.sbin/arp/Makefile.depend new file mode 100644 index 0000000..54c1f6f --- /dev/null +++ b/usr.sbin/arp/Makefile.depend @@ -0,0 +1,19 @@ +# $FreeBSD$ +# Autogenerated - do NOT edit! + +DIRDEPS = \ + gnu/lib/csu \ + gnu/lib/libgcc \ + include \ + include/arpa \ + include/xlocale \ + lib/${CSU_DIR} \ + lib/libc \ + lib/libcompiler_rt \ + + +.include <dirdeps.mk> + +.if ${DEP_RELDIR} == ${_DEP_RELDIR} +# local dependencies - needed for -jN in clean tree +.endif diff --git a/usr.sbin/arp/arp.4 b/usr.sbin/arp/arp.4 new file mode 100644 index 0000000..7bfa8ec --- /dev/null +++ b/usr.sbin/arp/arp.4 @@ -0,0 +1,235 @@ +.\" Copyright (c) 1985, 1986, 1988, 1994 +.\" The Regents of the University of California. 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. +.\" 4. Neither the name of the University 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 REGENTS 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 REGENTS 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. +.\" +.\" @(#)arp4.4 6.5 (Berkeley) 4/18/94 +.\" $FreeBSD$ +.\" +.Dd November 5, 2013 +.Dt ARP 4 +.Os +.Sh NAME +.Nm arp +.Nd Address Resolution Protocol +.Sh SYNOPSIS +.Cd "device ether" +.Sh DESCRIPTION +The Address Resolution Protocol (ARP) is used to dynamically +map between Protocol Addresses (such as IP addresses) and +Local Network Addresses (such as Ethernet addresses). +This implementation maps IP addresses to Ethernet, +ARCnet, +or Token Ring addresses. +It is used by all the Ethernet interface drivers. +.Pp +ARP caches Internet-Ethernet address mappings. +When an interface requests a mapping for an address not in the cache, +ARP queues the message which requires the mapping and broadcasts +a message on the associated network requesting the address mapping. +If a response is provided, the new mapping is cached and any pending +message is transmitted. +ARP will queue at most one packet while waiting for a response to a +mapping request; +only the most recently ``transmitted'' packet is kept. +If the target host does not respond after several requests, +the host is considered to be down allowing an error to be returned to +transmission attempts. +Further demand for this mapping causes ARP request retransmissions, that +are ratelimited to one packet per second. +The error is +.Er EHOSTDOWN +for a non-responding destination host, and +.Er EHOSTUNREACH +for a non-responding router. +.Pp +The ARP cache is stored in the system routing table as +dynamically-created host routes. +The route to a directly-attached Ethernet network is installed as a +.Dq cloning +route (one with the +.Li RTF_CLONING +flag set), +causing routes to individual hosts on that network to be created on +demand. +These routes time out periodically (normally 20 minutes after validated; +entries are not validated when not in use). +.Pp +ARP entries may be added, deleted or changed with the +.Xr arp 8 +utility. +Manually-added entries may be temporary or permanent, +and may be +.Dq published , +in which case the system will respond to ARP requests for that host +as if it were the target of the request. +.Pp +In the past, +ARP was used to negotiate the use of a trailer encapsulation. +This is no longer supported. +.Pp +ARP watches passively for hosts impersonating the local host (i.e., a host +which responds to an ARP mapping request for the local host's address). +.Pp +Proxy ARP is a feature whereby the local host will respond to requests +for addresses other than itself, with its own address. +Normally, proxy ARP in +.Fx +is set up on a host-by-host basis using the +.Xr arp 8 +utility, by adding an entry for each host inside a given subnet for +which proxying of ARP requests is desired. +However, the +.Dq "proxy all" +feature causes the local host to act as a proxy for +.Em all +hosts reachable through some other network interface, +different from the one the request came in from. +It may be enabled by setting the +.Xr sysctl 8 +MIB variable +.Va net.link.ether.inet.proxyall +to 1. +.Sh MIB Variables +The ARP protocol implements a number of configurable variables in +.Va net.link.ether.inet +branch +of the +.Xr sysctl 3 +MIB. +.Bl -tag -width "log_arp_permanent_modify" +.It Va allow_multicast +Should the kernel install ARP entries with multicast bit set in +the hardware address. +Installing such entries is RFC 1812 violation, but some prorietary +load balancing techniques require routers on network to do so. +Turned off by default. +.It Va log_arp_movements +Should the kernel log movements of IP addresses from one hardware +address to an other. +See +.Sx DIAGNOSTICS +below. +Turned on by default. +.It Va log_arp_permanent_modify +Should the kernel log attempts of remote host on network to modify a +permanent ARP entry. +See +.Sx DIAGNOSTICS +below. +Turned on by default. +.It Va log_arp_wrong_iface +Should the kernel log attempts to insert an ARP entry on an interface +when the IP network the address belongs to is connected to an other +interface. +See +.Sx DIAGNOSTICS +below. +Turned on by default. +.It Va max_log_per_second +Limit number of remotely triggered logging events to a configured value +per second. +Default is 1 log message per second. +.It Va max_age +How long an ARP entry is held in the cache until it needs to be refreshed. +Default is 1200 seconds. +.It Va maxhold +How many packets hold in the per-entry output queue while the entry +is being resolved. +Default is one packet. +.It Va maxtries +Number of retransmits before host is considered down and error is returned. +Default is 5 tries. +.It Va proxyall +Enables ARP proxying for all hosts on net. +Turned off by default. +.It Va wait +Lifetime of an incomplete ARP entry. +Default is 20 seconds. +.El +.Sh DIAGNOSTICS +.Bl -diag +.It "arp: %x:%x:%x:%x:%x:%x is using my IP address %d.%d.%d.%d on %s!" +ARP has discovered another host on the local network which responds to +mapping requests for its own Internet address with a different Ethernet +address, generally indicating that two hosts are attempting to use the +same Internet address. +.It "arp: link address is broadcast for IP address %d.%d.%d.%d!" +ARP requested information for a host, and received an answer indicating +that the host's ethernet address is the ethernet broadcast address. +This indicates a misconfigured or broken device. +.It "arp: %d.%d.%d.%d moved from %x:%x:%x:%x:%x:%x to %x:%x:%x:%x:%x:%x on %s" +ARP had a cached value for the ethernet address of the referenced host, +but received a reply indicating that the host is at a new address. +This can happen normally when host hardware addresses change, +or when a mobile node arrives or leaves the local subnet. +It can also indicate a problem with proxy ARP. +This message can only be issued if the sysctl +.Va net.link.ether.inet.log_arp_movements +is set to 1, which is the system's default behaviour. +.It "arpresolve: can't allocate llinfo for %d.%d.%d.%d" +The route for the referenced host points to a device upon which ARP is +required, but ARP was unable to allocate a routing table entry in which +to store the host's MAC address. +This usually points to a misconfigured routing table. +It can also occur if the kernel cannot allocate memory. +.It "arp: %d.%d.%d.%d is on if0 but got reply from %x:%x:%x:%x:%x:%x on if1" +Physical connections exist to the same logical IP network on both if0 and if1. +It can also occur if an entry already exists in the ARP cache for the IP +address above, and the cable has been disconnected from if0, then reconnected +to if1. +This message can only be issued if the sysctl +.Va net.link.ether.inet.log_arp_wrong_iface +is set to 1, which is the system's default behaviour. +.It "arp: %x:%x:%x:%x:%x:%x attempts to modify permanent entry for %d.%d.%d.%d on %s" +ARP has received an ARP reply that attempts to overwrite a permanent +entry in the local ARP table. +This error will only be logged if the sysctl +.Va net.link.ether.inet.log_arp_permanent_modify +is set to 1, which is the system's default behaviour. +.It "arp: %x:%x:%x:%x:%x:%x is multicast" +Kernel refused to install an entry with multicast hardware address. +If you really want such addresses being installed, set the sysctl +.Va net.link.ether.inet.allow_multicast +to a positive value. +.El +.Sh SEE ALSO +.Xr inet 4 , +.Xr route 4 , +.Xr arp 8 , +.Xr ifconfig 8 , +.Xr route 8 , +.Xr sysctl 8 +.Rs +.%A Plummer, D. +.%B "An Ethernet Address Resolution Protocol" +.%T RFC826 +.Re +.Rs +.%A Leffler, S.J. +.%A Karels, M.J. +.%B "Trailer Encapsulations" +.%T RFC893 +.Re diff --git a/usr.sbin/arp/arp.8 b/usr.sbin/arp/arp.8 new file mode 100644 index 0000000..87c5c5f --- /dev/null +++ b/usr.sbin/arp/arp.8 @@ -0,0 +1,192 @@ +.\" Copyright (c) 1985, 1991, 1993 +.\" The Regents of the University of California. 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. +.\" 4. Neither the name of the University 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 REGENTS 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 REGENTS 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. +.\" +.\" @(#)arp.8 8.1 (Berkeley) 6/6/93 +.\" $FreeBSD$ +.\" +.Dd January 31, 2013 +.Dt ARP 8 +.Os +.Sh NAME +.Nm arp +.Nd address resolution display and control +.Sh SYNOPSIS +.Nm +.Op Fl n +.Op Fl i Ar interface +.Ar hostname +.Nm +.Op Fl n +.Op Fl i Ar interface +.Fl a +.Nm +.Fl d Ar hostname +.Op Cm pub +.Nm +.Fl d +.Op Fl i Ar interface +.Fl a +.Nm +.Fl s Ar hostname ether_addr +.Op Cm temp +.Op Cm blackhole No \&| Cm reject +.Op Cm pub +.Nm +.Fl S Ar hostname ether_addr +.Op Cm temp +.Op Cm blackhole No \&| Cm reject +.Op Cm pub +.Nm +.Fl f Ar filename +.Sh DESCRIPTION +The +.Nm +utility displays and modifies the Internet-to-Ethernet address translation +tables used by the address resolution protocol +.Pq Xr arp 4 . +With no flags, the program displays the current +.Tn ARP +entry for +.Ar hostname . +The host may be specified by name or by number, +using Internet dot notation. +.Pp +Available options: +.Bl -tag -width indent +.It Fl a +The program displays or deletes all of the current +.Tn ARP +entries. +.It Fl d +A super-user may delete an entry for the host called +.Ar hostname +with the +.Fl d +flag. +If the +.Cm pub +keyword is specified, only the +.Dq published +.Tn ARP +entry +for this host will be deleted. +.Pp +Alternatively, the +.Fl d +flag may be combined with the +.Fl a +flag to delete all entries. +.It Fl i Ar interface +Limit the operation scope to the +.Tn ARP +entries on +.Ar interface . +Applicable only to the following operations: +display one, display all, delete all. +.It Fl n +Show network addresses as numbers (normally +.Nm +attempts to display addresses symbolically). +.It Fl s Ar hostname ether_addr +Create an +.Tn ARP +entry for the host called +.Ar hostname +with the Ethernet address +.Ar ether_addr . +The Ethernet address is given as six hex bytes separated by colons. +The entry will be permanent unless the word +.Cm temp +is given in the command. +If the word +.Cm pub +is given, the entry will be +.Dq published ; +i.e., this system will +act as an +.Tn ARP +server, +responding to requests for +.Ar hostname +even though the host address is not its own. +In this case the +.Ar ether_addr +can be given as +.Cm auto +in which case the interfaces on this host will be examined, +and if one of them is found to occupy the same subnet, its +Ethernet address will be used. +.Pp +If the +.Cm reject +keyword is specified the entry will be marked so that traffic to +the host will be discarded and the sender will be notified the +host is unreachable. +The +.Cm blackhole +keyword is similar in that traffic is discarded but the sender is +not notified. +These can be used to block external traffic to a host without +using a firewall. +.It Fl S Ar hostname ether_addr +Is just like +.Fl s +except any existing +.Tn ARP +entry for this host will be deleted first. +.It Fl f Ar filename +Cause the file +.Ar filename +to be read and multiple entries to be set in the +.Tn ARP +tables. +Entries +in the file should be of the form +.Pp +.Bd -ragged -offset indent -compact +.Ar hostname ether_addr +.Op Cm temp +.Op Cm blackhole No \&| Cm reject +.Op Cm pub +.Ed +.Pp +with argument meanings as given above. +Leading whitespace and empty lines are ignored. +A +.Ql # +character will mark the rest of the line as a comment. +.El +.Sh SEE ALSO +.Xr inet 3 , +.Xr arp 4 , +.Xr ifconfig 8 , +.Xr ndp 8 +.Sh HISTORY +The +.Nm +utility appeared in +.Bx 4.3 . diff --git a/usr.sbin/arp/arp.c b/usr.sbin/arp/arp.c new file mode 100644 index 0000000..eefde75 --- /dev/null +++ b/usr.sbin/arp/arp.c @@ -0,0 +1,882 @@ +/* + * Copyright (c) 1984, 1993 + * The Regents of the University of California. All rights reserved. + * + * This code is derived from software contributed to Berkeley by + * Sun Microsystems, Inc. + * + * 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. + * 4. Neither the name of the University 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 REGENTS 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 REGENTS 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. + */ + +#if 0 +#ifndef lint +static char const copyright[] = +"@(#) Copyright (c) 1984, 1993\n\ + The Regents of the University of California. All rights reserved.\n"; +#endif /* not lint */ + +#ifndef lint +static char const sccsid[] = "@(#)from: arp.c 8.2 (Berkeley) 1/2/94"; +#endif /* not lint */ +#endif +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +/* + * arp - display, set, and delete arp table entries + */ + + +#include <sys/param.h> +#include <sys/file.h> +#include <sys/socket.h> +#include <sys/sockio.h> +#include <sys/sysctl.h> +#include <sys/ioctl.h> +#include <sys/time.h> + +#include <net/if.h> +#include <net/if_dl.h> +#include <net/if_types.h> +#include <net/route.h> +#include <net/iso88025.h> + +#include <netinet/in.h> +#include <netinet/if_ether.h> + +#include <arpa/inet.h> + +#include <ctype.h> +#include <err.h> +#include <errno.h> +#include <netdb.h> +#include <nlist.h> +#include <paths.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <strings.h> +#include <unistd.h> + +typedef void (action_fn)(struct sockaddr_dl *sdl, + struct sockaddr_in *s_in, struct rt_msghdr *rtm); + +static int search(u_long addr, action_fn *action); +static action_fn print_entry; +static action_fn nuke_entry; + +static int delete(char *host); +static void usage(void); +static int set(int argc, char **argv); +static int get(char *host); +static int file(char *name); +static struct rt_msghdr *rtmsg(int cmd, + struct sockaddr_in *dst, struct sockaddr_dl *sdl); +static int get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr); +static struct sockaddr_in *getaddr(char *host); +static int valid_type(int type); + +static int nflag; /* no reverse dns lookups */ +static char *rifname; + +static time_t expire_time; +static int flags, doing_proxy; + +struct if_nameindex *ifnameindex; + +/* which function we're supposed to do */ +#define F_GET 1 +#define F_SET 2 +#define F_FILESET 3 +#define F_REPLACE 4 +#define F_DELETE 5 + +#define SETFUNC(f) { if (func) usage(); func = (f); } + +int +main(int argc, char *argv[]) +{ + int ch, func = 0; + int rtn = 0; + int aflag = 0; /* do it for all entries */ + + while ((ch = getopt(argc, argv, "andfsSi:")) != -1) + switch(ch) { + case 'a': + aflag = 1; + break; + case 'd': + SETFUNC(F_DELETE); + break; + case 'n': + nflag = 1; + break; + case 'S': + SETFUNC(F_REPLACE); + break; + case 's': + SETFUNC(F_SET); + break; + case 'f' : + SETFUNC(F_FILESET); + break; + case 'i': + rifname = optarg; + break; + case '?': + default: + usage(); + } + argc -= optind; + argv += optind; + + if (!func) + func = F_GET; + if (rifname) { + if (func != F_GET && !(func == F_DELETE && aflag)) + errx(1, "-i not applicable to this operation"); + if (if_nametoindex(rifname) == 0) { + if (errno == ENXIO) + errx(1, "interface %s does not exist", rifname); + else + err(1, "if_nametoindex(%s)", rifname); + } + } + switch (func) { + case F_GET: + if (aflag) { + if (argc != 0) + usage(); + search(0, print_entry); + } else { + if (argc != 1) + usage(); + rtn = get(argv[0]); + } + break; + case F_SET: + case F_REPLACE: + if (argc < 2 || argc > 6) + usage(); + if (func == F_REPLACE) + (void)delete(argv[0]); + rtn = set(argc, argv) ? 1 : 0; + break; + case F_DELETE: + if (aflag) { + if (argc != 0) + usage(); + search(0, nuke_entry); + } else { + if (argc != 1) + usage(); + rtn = delete(argv[0]); + } + break; + case F_FILESET: + if (argc != 1) + usage(); + rtn = file(argv[0]); + break; + } + + if (ifnameindex != NULL) + if_freenameindex(ifnameindex); + + return (rtn); +} + +/* + * Process a file to set standard arp entries + */ +static int +file(char *name) +{ + FILE *fp; + int i, retval; + char line[100], arg[5][50], *args[5], *p; + + if ((fp = fopen(name, "r")) == NULL) + err(1, "cannot open %s", name); + args[0] = &arg[0][0]; + args[1] = &arg[1][0]; + args[2] = &arg[2][0]; + args[3] = &arg[3][0]; + args[4] = &arg[4][0]; + retval = 0; + while(fgets(line, sizeof(line), fp) != NULL) { + if ((p = strchr(line, '#')) != NULL) + *p = '\0'; + for (p = line; isblank(*p); p++); + if (*p == '\n' || *p == '\0') + continue; + i = sscanf(p, "%49s %49s %49s %49s %49s", arg[0], arg[1], + arg[2], arg[3], arg[4]); + if (i < 2) { + warnx("bad line: %s", line); + retval = 1; + continue; + } + if (set(i, args)) + retval = 1; + } + fclose(fp); + return (retval); +} + +/* + * Given a hostname, fills up a (static) struct sockaddr_in with + * the address of the host and returns a pointer to the + * structure. + */ +static struct sockaddr_in * +getaddr(char *host) +{ + struct hostent *hp; + static struct sockaddr_in reply; + + bzero(&reply, sizeof(reply)); + reply.sin_len = sizeof(reply); + reply.sin_family = AF_INET; + reply.sin_addr.s_addr = inet_addr(host); + if (reply.sin_addr.s_addr == INADDR_NONE) { + if (!(hp = gethostbyname(host))) { + warnx("%s: %s", host, hstrerror(h_errno)); + return (NULL); + } + bcopy((char *)hp->h_addr, (char *)&reply.sin_addr, + sizeof reply.sin_addr); + } + return (&reply); +} + +/* + * Returns true if the type is a valid one for ARP. + */ +static int +valid_type(int type) +{ + + switch (type) { + case IFT_ETHER: + case IFT_FDDI: + case IFT_INFINIBAND: + case IFT_ISO88023: + case IFT_ISO88024: + case IFT_ISO88025: + case IFT_L2VLAN: + case IFT_BRIDGE: + return (1); + default: + return (0); + } +} + +/* + * Set an individual arp entry + */ +static int +set(int argc, char **argv) +{ + struct sockaddr_in *addr; + struct sockaddr_in *dst; /* what are we looking for */ + struct sockaddr_dl *sdl; + struct rt_msghdr *rtm; + struct ether_addr *ea; + char *host = argv[0], *eaddr = argv[1]; + struct sockaddr_dl sdl_m; + + argc -= 2; + argv += 2; + + bzero(&sdl_m, sizeof(sdl_m)); + sdl_m.sdl_len = sizeof(sdl_m); + sdl_m.sdl_family = AF_LINK; + + dst = getaddr(host); + if (dst == NULL) + return (1); + doing_proxy = flags = expire_time = 0; + while (argc-- > 0) { + if (strncmp(argv[0], "temp", 4) == 0) { + struct timespec tp; + int max_age; + size_t len = sizeof(max_age); + + clock_gettime(CLOCK_MONOTONIC, &tp); + if (sysctlbyname("net.link.ether.inet.max_age", + &max_age, &len, NULL, 0) != 0) + err(1, "sysctlbyname"); + expire_time = tp.tv_sec + max_age; + } else if (strncmp(argv[0], "pub", 3) == 0) { + flags |= RTF_ANNOUNCE; + doing_proxy = 1; + if (argc && strncmp(argv[1], "only", 3) == 0) { + /* + * Compatibility: in pre FreeBSD 8 times + * the "only" keyword used to mean that + * an ARP entry should be announced, but + * not installed into routing table. + */ + argc--; argv++; + } + } else if (strncmp(argv[0], "blackhole", 9) == 0) { + if (flags & RTF_REJECT) { + printf("Choose one of blackhole or reject, not both.\n"); + } + flags |= RTF_BLACKHOLE; + } else if (strncmp(argv[0], "reject", 6) == 0) { + if (flags & RTF_BLACKHOLE) { + printf("Choose one of blackhole or reject, not both.\n"); + } + flags |= RTF_REJECT; + } else if (strncmp(argv[0], "trail", 5) == 0) { + /* XXX deprecated and undocumented feature */ + printf("%s: Sending trailers is no longer supported\n", + host); + } + argv++; + } + ea = (struct ether_addr *)LLADDR(&sdl_m); + if (doing_proxy && !strcmp(eaddr, "auto")) { + if (!get_ether_addr(dst->sin_addr.s_addr, ea)) { + printf("no interface found for %s\n", + inet_ntoa(dst->sin_addr)); + return (1); + } + sdl_m.sdl_alen = ETHER_ADDR_LEN; + } else { + struct ether_addr *ea1 = ether_aton(eaddr); + + if (ea1 == NULL) { + warnx("invalid Ethernet address '%s'", eaddr); + return (1); + } else { + *ea = *ea1; + sdl_m.sdl_alen = ETHER_ADDR_LEN; + } + } + + /* + * In the case a proxy-arp entry is being added for + * a remote end point, the RTF_ANNOUNCE flag in the + * RTM_GET command is an indication to the kernel + * routing code that the interface associated with + * the prefix route covering the local end of the + * PPP link should be returned, on which ARP applies. + */ + rtm = rtmsg(RTM_GET, dst, &sdl_m); + if (rtm == NULL) { + warn("%s", host); + return (1); + } + addr = (struct sockaddr_in *)(rtm + 1); + sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr); + + if ((sdl->sdl_family != AF_LINK) || + (rtm->rtm_flags & RTF_GATEWAY) || + !valid_type(sdl->sdl_type)) { + printf("cannot intuit interface index and type for %s\n", host); + return (1); + } + sdl_m.sdl_type = sdl->sdl_type; + sdl_m.sdl_index = sdl->sdl_index; + return (rtmsg(RTM_ADD, dst, &sdl_m) == NULL); +} + +/* + * Display an individual arp entry + */ +static int +get(char *host) +{ + struct sockaddr_in *addr; + + addr = getaddr(host); + if (addr == NULL) + return (1); + if (0 == search(addr->sin_addr.s_addr, print_entry)) { + printf("%s (%s) -- no entry", + host, inet_ntoa(addr->sin_addr)); + if (rifname) + printf(" on %s", rifname); + printf("\n"); + return (1); + } + return (0); +} + +/* + * Delete an arp entry + */ +static int +delete(char *host) +{ + struct sockaddr_in *addr, *dst; + struct rt_msghdr *rtm; + struct sockaddr_dl *sdl; + struct sockaddr_dl sdl_m; + + dst = getaddr(host); + if (dst == NULL) + return (1); + + /* + * Perform a regular entry delete first. + */ + flags &= ~RTF_ANNOUNCE; + + /* + * setup the data structure to notify the kernel + * it is the ARP entry the RTM_GET is interested + * in + */ + bzero(&sdl_m, sizeof(sdl_m)); + sdl_m.sdl_len = sizeof(sdl_m); + sdl_m.sdl_family = AF_LINK; + + for (;;) { /* try twice */ + rtm = rtmsg(RTM_GET, dst, &sdl_m); + if (rtm == NULL) { + warn("%s", host); + return (1); + } + addr = (struct sockaddr_in *)(rtm + 1); + sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr); + + /* + * With the new L2/L3 restructure, the route + * returned is a prefix route. The important + * piece of information from the previous + * RTM_GET is the interface index. In the + * case of ECMP, the kernel will traverse + * the route group for the given entry. + */ + if (sdl->sdl_family == AF_LINK && + !(rtm->rtm_flags & RTF_GATEWAY) && + valid_type(sdl->sdl_type) ) { + addr->sin_addr.s_addr = dst->sin_addr.s_addr; + break; + } + + /* + * Regualar entry delete failed, now check if there + * is a proxy-arp entry to remove. + */ + if (flags & RTF_ANNOUNCE) { + fprintf(stderr, "delete: cannot locate %s\n",host); + return (1); + } + + flags |= RTF_ANNOUNCE; + } + rtm->rtm_flags |= RTF_LLDATA; + if (rtmsg(RTM_DELETE, dst, NULL) != NULL) { + printf("%s (%s) deleted\n", host, inet_ntoa(addr->sin_addr)); + return (0); + } + return (1); +} + + +/* + * Search the arp table and do some action on matching entries + */ +static int +search(u_long addr, action_fn *action) +{ + int mib[6]; + size_t needed; + char *lim, *buf, *next; + struct rt_msghdr *rtm; + struct sockaddr_in *sin2; + struct sockaddr_dl *sdl; + char ifname[IF_NAMESIZE]; + int st, found_entry = 0; + + mib[0] = CTL_NET; + mib[1] = PF_ROUTE; + mib[2] = 0; + mib[3] = AF_INET; + mib[4] = NET_RT_FLAGS; +#ifdef RTF_LLINFO + mib[5] = RTF_LLINFO; +#else + mib[5] = 0; +#endif + if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) + err(1, "route-sysctl-estimate"); + if (needed == 0) /* empty table */ + return 0; + buf = NULL; + for (;;) { + buf = reallocf(buf, needed); + if (buf == NULL) + errx(1, "could not reallocate memory"); + st = sysctl(mib, 6, buf, &needed, NULL, 0); + if (st == 0 || errno != ENOMEM) + break; + needed += needed / 8; + } + if (st == -1) + err(1, "actual retrieval of routing table"); + lim = buf + needed; + for (next = buf; next < lim; next += rtm->rtm_msglen) { + rtm = (struct rt_msghdr *)next; + sin2 = (struct sockaddr_in *)(rtm + 1); + sdl = (struct sockaddr_dl *)((char *)sin2 + SA_SIZE(sin2)); + if (rifname && if_indextoname(sdl->sdl_index, ifname) && + strcmp(ifname, rifname)) + continue; + if (addr) { + if (addr != sin2->sin_addr.s_addr) + continue; + found_entry = 1; + } + (*action)(sdl, sin2, rtm); + } + free(buf); + return (found_entry); +} + +/* + * Display an arp entry + */ + +static void +print_entry(struct sockaddr_dl *sdl, + struct sockaddr_in *addr, struct rt_msghdr *rtm) +{ + const char *host; + struct hostent *hp; + struct iso88025_sockaddr_dl_data *trld; + struct if_nameindex *p; + int seg; + + if (ifnameindex == NULL) + if ((ifnameindex = if_nameindex()) == NULL) + err(1, "cannot retrieve interface names"); + + if (nflag == 0) + hp = gethostbyaddr((caddr_t)&(addr->sin_addr), + sizeof addr->sin_addr, AF_INET); + else + hp = 0; + if (hp) + host = hp->h_name; + else { + host = "?"; + if (h_errno == TRY_AGAIN) + nflag = 1; + } + printf("%s (%s) at ", host, inet_ntoa(addr->sin_addr)); + if (sdl->sdl_alen) { + if ((sdl->sdl_type == IFT_ETHER || + sdl->sdl_type == IFT_L2VLAN || + sdl->sdl_type == IFT_BRIDGE) && + sdl->sdl_alen == ETHER_ADDR_LEN) + printf("%s", ether_ntoa((struct ether_addr *)LLADDR(sdl))); + else { + int n = sdl->sdl_nlen > 0 ? sdl->sdl_nlen + 1 : 0; + + printf("%s", link_ntoa(sdl) + n); + } + } else + printf("(incomplete)"); + + for (p = ifnameindex; p && ifnameindex->if_index && + ifnameindex->if_name; p++) { + if (p->if_index == sdl->sdl_index) { + printf(" on %s", p->if_name); + break; + } + } + + if (rtm->rtm_rmx.rmx_expire == 0) + printf(" permanent"); + else { + static struct timespec tp; + if (tp.tv_sec == 0) + clock_gettime(CLOCK_MONOTONIC, &tp); + if ((expire_time = rtm->rtm_rmx.rmx_expire - tp.tv_sec) > 0) + printf(" expires in %d seconds", (int)expire_time); + else + printf(" expired"); + } + if (rtm->rtm_flags & RTF_ANNOUNCE) + printf(" published"); + switch(sdl->sdl_type) { + case IFT_ETHER: + printf(" [ethernet]"); + break; + case IFT_ISO88025: + printf(" [token-ring]"); + trld = SDL_ISO88025(sdl); + if (trld->trld_rcf != 0) { + printf(" rt=%x", ntohs(trld->trld_rcf)); + for (seg = 0; + seg < ((TR_RCF_RIFLEN(trld->trld_rcf) - 2 ) / 2); + seg++) + printf(":%x", ntohs(*(trld->trld_route[seg]))); + } + break; + case IFT_FDDI: + printf(" [fddi]"); + break; + case IFT_ATM: + printf(" [atm]"); + break; + case IFT_L2VLAN: + printf(" [vlan]"); + break; + case IFT_IEEE1394: + printf(" [firewire]"); + break; + case IFT_BRIDGE: + printf(" [bridge]"); + break; + case IFT_INFINIBAND: + printf(" [infiniband]"); + break; + default: + break; + } + + printf("\n"); + +} + +/* + * Nuke an arp entry + */ +static void +nuke_entry(struct sockaddr_dl *sdl __unused, + struct sockaddr_in *addr, struct rt_msghdr *rtm) +{ + char ip[20]; + + if (rtm->rtm_flags & RTF_PINNED) + return; + + snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr)); + delete(ip); +} + +static void +usage(void) +{ + fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n", + "usage: arp [-n] [-i interface] hostname", + " arp [-n] [-i interface] -a", + " arp -d hostname [pub]", + " arp -d [-i interface] -a", + " arp -s hostname ether_addr [temp] [reject | blackhole] [pub [only]]", + " arp -S hostname ether_addr [temp] [reject | blackhole] [pub [only]]", + " arp -f filename"); + exit(1); +} + +static struct rt_msghdr * +rtmsg(int cmd, struct sockaddr_in *dst, struct sockaddr_dl *sdl) +{ + static int seq; + int rlen; + int l; + struct sockaddr_in so_mask, *som = &so_mask; + static int s = -1; + static pid_t pid; + + static struct { + struct rt_msghdr m_rtm; + char m_space[512]; + } m_rtmsg; + + struct rt_msghdr *rtm = &m_rtmsg.m_rtm; + char *cp = m_rtmsg.m_space; + + if (s < 0) { /* first time: open socket, get pid */ + s = socket(PF_ROUTE, SOCK_RAW, 0); + if (s < 0) + err(1, "socket"); + pid = getpid(); + } + bzero(&so_mask, sizeof(so_mask)); + so_mask.sin_len = 8; + so_mask.sin_addr.s_addr = 0xffffffff; + + errno = 0; + /* + * XXX RTM_DELETE relies on a previous RTM_GET to fill the buffer + * appropriately. + */ + if (cmd == RTM_DELETE) + goto doit; + bzero((char *)&m_rtmsg, sizeof(m_rtmsg)); + rtm->rtm_flags = flags; + rtm->rtm_version = RTM_VERSION; + + switch (cmd) { + default: + errx(1, "internal wrong cmd"); + case RTM_ADD: + rtm->rtm_addrs |= RTA_GATEWAY; + rtm->rtm_rmx.rmx_expire = expire_time; + rtm->rtm_inits = RTV_EXPIRE; + rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA); + if (doing_proxy) { + rtm->rtm_addrs |= RTA_NETMASK; + rtm->rtm_flags &= ~RTF_HOST; + } + /* FALLTHROUGH */ + case RTM_GET: + rtm->rtm_addrs |= RTA_DST; + } +#define NEXTADDR(w, s) \ + do { \ + if ((s) != NULL && rtm->rtm_addrs & (w)) { \ + bcopy((s), cp, sizeof(*(s))); \ + cp += SA_SIZE(s); \ + } \ + } while (0) + + NEXTADDR(RTA_DST, dst); + NEXTADDR(RTA_GATEWAY, sdl); + NEXTADDR(RTA_NETMASK, som); + + rtm->rtm_msglen = cp - (char *)&m_rtmsg; +doit: + l = rtm->rtm_msglen; + rtm->rtm_seq = ++seq; + rtm->rtm_type = cmd; + if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) { + if (errno != ESRCH || cmd != RTM_DELETE) { + warn("writing to routing socket"); + return (NULL); + } + } + do { + l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg)); + } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid)); + if (l < 0) + warn("read from routing socket"); + return (rtm); +} + +/* + * get_ether_addr - get the hardware address of an interface on the + * the same subnet as ipaddr. + */ +#define MAX_IFS 32 + +static int +get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr) +{ + struct ifreq *ifr, *ifend, *ifp; + in_addr_t ina, mask; + struct sockaddr_dl *dla; + struct ifreq ifreq; + struct ifconf ifc; + struct ifreq ifs[MAX_IFS]; + int sock; + int retval = 0; + + sock = socket(AF_INET, SOCK_DGRAM, 0); + if (sock < 0) + err(1, "socket"); + + ifc.ifc_len = sizeof(ifs); + ifc.ifc_req = ifs; + if (ioctl(sock, SIOCGIFCONF, &ifc) < 0) { + warnx("ioctl(SIOCGIFCONF)"); + goto done; + } + +#define NEXTIFR(i) \ + ((struct ifreq *)((char *)&(i)->ifr_addr \ + + MAX((i)->ifr_addr.sa_len, sizeof((i)->ifr_addr))) ) + + /* + * Scan through looking for an interface with an Internet + * address on the same subnet as `ipaddr'. + */ + ifend = (struct ifreq *)(ifc.ifc_buf + ifc.ifc_len); + for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr) ) { + if (ifr->ifr_addr.sa_family != AF_INET) + continue; + strncpy(ifreq.ifr_name, ifr->ifr_name, + sizeof(ifreq.ifr_name)); + ifreq.ifr_addr = ifr->ifr_addr; + /* + * Check that the interface is up, + * and not point-to-point or loopback. + */ + if (ioctl(sock, SIOCGIFFLAGS, &ifreq) < 0) + continue; + if ((ifreq.ifr_flags & + (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT| + IFF_LOOPBACK|IFF_NOARP)) + != (IFF_UP|IFF_BROADCAST)) + continue; + /* + * Get its netmask and check that it's on + * the right subnet. + */ + if (ioctl(sock, SIOCGIFNETMASK, &ifreq) < 0) + continue; + mask = ((struct sockaddr_in *) + &ifreq.ifr_addr)->sin_addr.s_addr; + ina = ((struct sockaddr_in *) + &ifr->ifr_addr)->sin_addr.s_addr; + if ((ipaddr & mask) == (ina & mask)) + break; /* ok, we got it! */ + } + + if (ifr >= ifend) + goto done; + + /* + * Now scan through again looking for a link-level address + * for this interface. + */ + ifp = ifr; + for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr)) + if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0 && + ifr->ifr_addr.sa_family == AF_LINK) + break; + if (ifr >= ifend) + goto done; + /* + * Found the link-level address - copy it out + */ + dla = (struct sockaddr_dl *) &ifr->ifr_addr; + memcpy(hwaddr, LLADDR(dla), dla->sdl_alen); + printf("using interface %s for proxy with address ", + ifp->ifr_name); + printf("%s\n", ether_ntoa(hwaddr)); + retval = dla->sdl_alen; +done: + close(sock); + return (retval); +} |
