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diff --git a/share/man/man4/ip.4 b/share/man/man4/ip.4 new file mode 100644 index 0000000..b95a350 --- /dev/null +++ b/share/man/man4/ip.4 @@ -0,0 +1,893 @@ +.\" Copyright (c) 1983, 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. +.\" 3. 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. +.\" +.\" @(#)ip.4 8.2 (Berkeley) 11/30/93 +.\" $FreeBSD$ +.\" +.Dd October 12, 2012 +.Dt IP 4 +.Os +.Sh NAME +.Nm ip +.Nd Internet Protocol +.Sh SYNOPSIS +.In sys/types.h +.In sys/socket.h +.In netinet/in.h +.Ft int +.Fn socket AF_INET SOCK_RAW proto +.Sh DESCRIPTION +.Tn IP +is the transport layer protocol used +by the Internet protocol family. +Options may be set at the +.Tn IP +level +when using higher-level protocols that are based on +.Tn IP +(such as +.Tn TCP +and +.Tn UDP ) . +It may also be accessed +through a +.Dq raw socket +when developing new protocols, or +special-purpose applications. +.Pp +There are several +.Tn IP-level +.Xr setsockopt 2 +and +.Xr getsockopt 2 +options. +.Dv IP_OPTIONS +may be used to provide +.Tn IP +options to be transmitted in the +.Tn IP +header of each outgoing packet +or to examine the header options on incoming packets. +.Tn IP +options may be used with any socket type in the Internet family. +The format of +.Tn IP +options to be sent is that specified by the +.Tn IP +protocol specification (RFC-791), with one exception: +the list of addresses for Source Route options must include the first-hop +gateway at the beginning of the list of gateways. +The first-hop gateway address will be extracted from the option list +and the size adjusted accordingly before use. +To disable previously specified options, +use a zero-length buffer: +.Bd -literal +setsockopt(s, IPPROTO_IP, IP_OPTIONS, NULL, 0); +.Ed +.Pp +.Dv IP_TOS +and +.Dv IP_TTL +may be used to set the type-of-service and time-to-live +fields in the +.Tn IP +header for +.Dv SOCK_STREAM , SOCK_DGRAM , +and certain types of +.Dv SOCK_RAW +sockets. +For example, +.Bd -literal +int tos = IPTOS_LOWDELAY; /* see <netinet/ip.h> */ +setsockopt(s, IPPROTO_IP, IP_TOS, &tos, sizeof(tos)); + +int ttl = 60; /* max = 255 */ +setsockopt(s, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl)); +.Ed +.Pp +.Dv IP_MINTTL +may be used to set the minimum acceptable TTL a packet must have when +received on a socket. +All packets with a lower TTL are silently dropped. +This option is only really useful when set to 255, preventing packets +from outside the directly connected networks reaching local listeners +on sockets. +.Pp +.Dv IP_DONTFRAG +may be used to set the Don't Fragment flag on IP packets. +Currently this option is respected only on +.Xr udp 4 +and raw +.Xr ip 4 +sockets, unless the +.Dv IP_HDRINCL +option has been set. +On +.Xr tcp 4 +sockets, the Don't Fragment flag is controlled by the Path +MTU Discovery option. +Sending a packet larger than the MTU size of the egress interface, +determined by the destination address, returns an +.Er EMSGSIZE +error. +.Pp +If the +.Dv IP_RECVDSTADDR +option is enabled on a +.Dv SOCK_DGRAM +socket, +the +.Xr recvmsg 2 +call will return the destination +.Tn IP +address for a +.Tn UDP +datagram. +The +.Vt msg_control +field in the +.Vt msghdr +structure points to a buffer +that contains a +.Vt cmsghdr +structure followed by the +.Tn IP +address. +The +.Vt cmsghdr +fields have the following values: +.Bd -literal +cmsg_len = CMSG_LEN(sizeof(struct in_addr)) +cmsg_level = IPPROTO_IP +cmsg_type = IP_RECVDSTADDR +.Ed +.Pp +The source address to be used for outgoing +.Tn UDP +datagrams on a socket can be specified as ancillary data with a type code of +.Dv IP_SENDSRCADDR . +The msg_control field in the msghdr structure should point to a buffer +that contains a +.Vt cmsghdr +structure followed by the +.Tn IP +address. +The cmsghdr fields should have the following values: +.Bd -literal +cmsg_len = CMSG_LEN(sizeof(struct in_addr)) +cmsg_level = IPPROTO_IP +cmsg_type = IP_SENDSRCADDR +.Ed +.Pp +The socket should be either bound to +.Dv INADDR_ANY +and a local port, and the address supplied with +.Dv IP_SENDSRCADDR +should't be +.Dv INADDR_ANY , +or the socket should be bound to a local address and the address supplied with +.Dv IP_SENDSRCADDR +should be +.Dv INADDR_ANY . +In the latter case bound address is overriden via generic source address +selection logic, which would choose IP address of interface closest to +destination. +.Pp +For convenience, +.Dv IP_SENDSRCADDR +is defined to have the same value as +.Dv IP_RECVDSTADDR , +so the +.Dv IP_RECVDSTADDR +control message from +.Xr recvmsg 2 +can be used directly as a control message for +.Xr sendmsg 2 . +.\" +.Pp +If the +.Dv IP_ONESBCAST +option is enabled on a +.Dv SOCK_DGRAM +or a +.Dv SOCK_RAW +socket, the destination address of outgoing +broadcast datagrams on that socket will be forced +to the undirected broadcast address, +.Dv INADDR_BROADCAST , +before transmission. +This is in contrast to the default behavior of the +system, which is to transmit undirected broadcasts +via the first network interface with the +.Dv IFF_BROADCAST +flag set. +.Pp +This option allows applications to choose which +interface is used to transmit an undirected broadcast +datagram. +For example, the following code would force an +undirected broadcast to be transmitted via the interface +configured with the broadcast address 192.168.2.255: +.Bd -literal +char msg[512]; +struct sockaddr_in sin; +int onesbcast = 1; /* 0 = disable (default), 1 = enable */ + +setsockopt(s, IPPROTO_IP, IP_ONESBCAST, &onesbcast, sizeof(onesbcast)); +sin.sin_addr.s_addr = inet_addr("192.168.2.255"); +sin.sin_port = htons(1234); +sendto(s, msg, sizeof(msg), 0, &sin, sizeof(sin)); +.Ed +.Pp +It is the application's responsibility to set the +.Dv IP_TTL +option +to an appropriate value in order to prevent broadcast storms. +The application must have sufficient credentials to set the +.Dv SO_BROADCAST +socket level option, otherwise the +.Dv IP_ONESBCAST +option has no effect. +.Pp +If the +.Dv IP_BINDANY +option is enabled on a +.Dv SOCK_STREAM , +.Dv SOCK_DGRAM +or a +.Dv SOCK_RAW +socket, one can +.Xr bind 2 +to any address, even one not bound to any available network interface in the +system. +This functionality (in conjunction with special firewall rules) can be used for +implementing a transparent proxy. +The +.Dv PRIV_NETINET_BINDANY +privilege is needed to set this option. +.Pp +If the +.Dv IP_RECVTTL +option is enabled on a +.Dv SOCK_DGRAM +socket, the +.Xr recvmsg 2 +call will return the +.Tn IP +.Tn TTL +(time to live) field for a +.Tn UDP +datagram. +The msg_control field in the msghdr structure points to a buffer +that contains a cmsghdr structure followed by the +.Tn TTL . +The cmsghdr fields have the following values: +.Bd -literal +cmsg_len = CMSG_LEN(sizeof(u_char)) +cmsg_level = IPPROTO_IP +cmsg_type = IP_RECVTTL +.Ed +.\" +.Pp +If the +.Dv IP_RECVTOS +option is enabled on a +.Dv SOCK_DGRAM +socket, the +.Xr recvmsg 2 +call will return the +.Tn IP +.Tn TOS +(type of service) field for a +.Tn UDP +datagram. +The msg_control field in the msghdr structure points to a buffer +that contains a cmsghdr structure followed by the +.Tn TOS . +The cmsghdr fields have the following values: +.Bd -literal +cmsg_len = CMSG_LEN(sizeof(u_char)) +cmsg_level = IPPROTO_IP +cmsg_type = IP_RECVTOS +.Ed +.\" +.Pp +If the +.Dv IP_RECVIF +option is enabled on a +.Dv SOCK_DGRAM +socket, the +.Xr recvmsg 2 +call returns a +.Vt "struct sockaddr_dl" +corresponding to the interface on which the +packet was received. +The +.Va msg_control +field in the +.Vt msghdr +structure points to a buffer that contains a +.Vt cmsghdr +structure followed by the +.Vt "struct sockaddr_dl" . +The +.Vt cmsghdr +fields have the following values: +.Bd -literal +cmsg_len = CMSG_LEN(sizeof(struct sockaddr_dl)) +cmsg_level = IPPROTO_IP +cmsg_type = IP_RECVIF +.Ed +.Pp +.Dv IP_PORTRANGE +may be used to set the port range used for selecting a local port number +on a socket with an unspecified (zero) port number. +It has the following +possible values: +.Bl -tag -width IP_PORTRANGE_DEFAULT +.It Dv IP_PORTRANGE_DEFAULT +use the default range of values, normally +.Dv IPPORT_HIFIRSTAUTO +through +.Dv IPPORT_HILASTAUTO . +This is adjustable through the sysctl setting: +.Va net.inet.ip.portrange.first +and +.Va net.inet.ip.portrange.last . +.It Dv IP_PORTRANGE_HIGH +use a high range of values, normally +.Dv IPPORT_HIFIRSTAUTO +and +.Dv IPPORT_HILASTAUTO . +This is adjustable through the sysctl setting: +.Va net.inet.ip.portrange.hifirst +and +.Va net.inet.ip.portrange.hilast . +.It Dv IP_PORTRANGE_LOW +use a low range of ports, which are normally restricted to +privileged processes on +.Ux +systems. +The range is normally from +.Dv IPPORT_RESERVED +\- 1 down to +.Li IPPORT_RESERVEDSTART +in descending order. +This is adjustable through the sysctl setting: +.Va net.inet.ip.portrange.lowfirst +and +.Va net.inet.ip.portrange.lowlast . +.El +.Pp +The range of privileged ports which only may be opened by +root-owned processes may be modified by the +.Va net.inet.ip.portrange.reservedlow +and +.Va net.inet.ip.portrange.reservedhigh +sysctl settings. +The values default to the traditional range, +0 through +.Dv IPPORT_RESERVED +\- 1 +(0 through 1023), respectively. +Note that these settings do not affect and are not accounted for in the +use or calculation of the other +.Va net.inet.ip.portrange +values above. +Changing these values departs from +.Ux +tradition and has security +consequences that the administrator should carefully evaluate before +modifying these settings. +.Pp +Ports are allocated at random within the specified port range in order +to increase the difficulty of random spoofing attacks. +In scenarios such as benchmarking, this behavior may be undesirable. +In these cases, +.Va net.inet.ip.portrange.randomized +can be used to toggle randomization off. +If more than +.Va net.inet.ip.portrange.randomcps +ports have been allocated in the last second, then return to sequential +port allocation. +Return to random allocation only once the current port allocation rate +drops below +.Va net.inet.ip.portrange.randomcps +for at least +.Va net.inet.ip.portrange.randomtime +seconds. +The default values for +.Va net.inet.ip.portrange.randomcps +and +.Va net.inet.ip.portrange.randomtime +are 10 port allocations per second and 45 seconds correspondingly. +.Ss "Multicast Options" +.Tn IP +multicasting is supported only on +.Dv AF_INET +sockets of type +.Dv SOCK_DGRAM +and +.Dv SOCK_RAW , +and only on networks where the interface +driver supports multicasting. +.Pp +The +.Dv IP_MULTICAST_TTL +option changes the time-to-live (TTL) +for outgoing multicast datagrams +in order to control the scope of the multicasts: +.Bd -literal +u_char ttl; /* range: 0 to 255, default = 1 */ +setsockopt(s, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)); +.Ed +.Pp +Datagrams with a TTL of 1 are not forwarded beyond the local network. +Multicast datagrams with a TTL of 0 will not be transmitted on any network, +but may be delivered locally if the sending host belongs to the destination +group and if multicast loopback has not been disabled on the sending socket +(see below). +Multicast datagrams with TTL greater than 1 may be forwarded +to other networks if a multicast router is attached to the local network. +.Pp +For hosts with multiple interfaces, where an interface has not +been specified for a multicast group membership, +each multicast transmission is sent from the primary network interface. +The +.Dv IP_MULTICAST_IF +option overrides the default for +subsequent transmissions from a given socket: +.Bd -literal +struct in_addr addr; +setsockopt(s, IPPROTO_IP, IP_MULTICAST_IF, &addr, sizeof(addr)); +.Ed +.Pp +where "addr" is the local +.Tn IP +address of the desired interface or +.Dv INADDR_ANY +to specify the default interface. +.Pp +To specify an interface by index, an instance of +.Vt ip_mreqn +may be passed instead. +The +.Vt imr_ifindex +member should be set to the index of the desired interface, +or 0 to specify the default interface. +The kernel differentiates between these two structures by their size. +.Pp +The use of +.Vt IP_MULTICAST_IF +is +.Em not recommended , +as multicast memberships are scoped to each +individual interface. +It is supported for legacy use only by applications, +such as routing daemons, which expect to +be able to transmit link-local IPv4 multicast datagrams (224.0.0.0/24) +on multiple interfaces, +without requesting an individual membership for each interface. +.Pp +.\" +An interface's local IP address and multicast capability can +be obtained via the +.Dv SIOCGIFCONF +and +.Dv SIOCGIFFLAGS +ioctls. +Normal applications should not need to use this option. +.Pp +If a multicast datagram is sent to a group to which the sending host itself +belongs (on the outgoing interface), a copy of the datagram is, by default, +looped back by the IP layer for local delivery. +The +.Dv IP_MULTICAST_LOOP +option gives the sender explicit control +over whether or not subsequent datagrams are looped back: +.Bd -literal +u_char loop; /* 0 = disable, 1 = enable (default) */ +setsockopt(s, IPPROTO_IP, IP_MULTICAST_LOOP, &loop, sizeof(loop)); +.Ed +.Pp +This option +improves performance for applications that may have no more than one +instance on a single host (such as a routing daemon), by eliminating +the overhead of receiving their own transmissions. +It should generally not +be used by applications for which there may be more than one instance on a +single host (such as a conferencing program) or for which the sender does +not belong to the destination group (such as a time querying program). +.Pp +The sysctl setting +.Va net.inet.ip.mcast.loop +controls the default setting of the +.Dv IP_MULTICAST_LOOP +socket option for new sockets. +.Pp +A multicast datagram sent with an initial TTL greater than 1 may be delivered +to the sending host on a different interface from that on which it was sent, +if the host belongs to the destination group on that other interface. +The loopback control option has no effect on such delivery. +.Pp +A host must become a member of a multicast group before it can receive +datagrams sent to the group. +To join a multicast group, use the +.Dv IP_ADD_MEMBERSHIP +option: +.Bd -literal +struct ip_mreq mreq; +setsockopt(s, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq)); +.Ed +.Pp +where +.Fa mreq +is the following structure: +.Bd -literal +struct ip_mreq { + struct in_addr imr_multiaddr; /* IP multicast address of group */ + struct in_addr imr_interface; /* local IP address of interface */ +} +.Ed +.Pp +.Va imr_interface +should be set to the +.Tn IP +address of a particular multicast-capable interface if +the host is multihomed. +It may be set to +.Dv INADDR_ANY +to choose the default interface, although this is not recommended; +this is considered to be the first interface corresponding +to the default route. +Otherwise, the first multicast-capable interface +configured in the system will be used. +.Pp +Prior to +.Fx 7.0 , +if the +.Va imr_interface +member is within the network range +.Li 0.0.0.0/8 , +it is treated as an interface index in the system interface MIB, +as per the RIP Version 2 MIB Extension (RFC-1724). +In versions of +.Fx +since 7.0, this behavior is no longer supported. +Developers should +instead use the RFC 3678 multicast source filter APIs; in particular, +.Dv MCAST_JOIN_GROUP . +.Pp +Up to +.Dv IP_MAX_MEMBERSHIPS +memberships may be added on a single socket. +Membership is associated with a single interface; +programs running on multihomed hosts may need to +join the same group on more than one interface. +.Pp +To drop a membership, use: +.Bd -literal +struct ip_mreq mreq; +setsockopt(s, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq, sizeof(mreq)); +.Ed +.Pp +where +.Fa mreq +contains the same values as used to add the membership. +Memberships are dropped when the socket is closed or the process exits. +.\" TODO: Update this piece when IPv4 source-address selection is implemented. +.Pp +The IGMP protocol uses the primary IP address of the interface +as its identifier for group membership. +This is the first IP address configured on the interface. +If this address is removed or changed, the results are +undefined, as the IGMP membership state will then be inconsistent. +If multiple IP aliases are configured on the same interface, +they will be ignored. +.Pp +This shortcoming was addressed in IPv6; MLDv2 requires +that the unique link-local address for an interface is +used to identify an MLDv2 listener. +.Ss "Source-Specific Multicast Options" +Since +.Fx 8.0 , +the use of Source-Specific Multicast (SSM) is supported. +These extensions require an IGMPv3 multicast router in order to +make best use of them. +If a legacy multicast router is present on the link, +.Fx +will simply downgrade to the version of IGMP spoken by the router, +and the benefits of source filtering on the upstream link +will not be present, although the kernel will continue to +squelch transmissions from blocked sources. +.Pp +Each group membership on a socket now has a filter mode: +.Bl -tag -width MCAST_EXCLUDE +.It Dv MCAST_EXCLUDE +Datagrams sent to this group are accepted, +unless the source is in a list of blocked source addresses. +.It Dv MCAST_INCLUDE +Datagrams sent to this group are accepted +only if the source is in a list of accepted source addresses. +.El +.Pp +Groups joined using the legacy +.Dv IP_ADD_MEMBERSHIP +option are placed in exclusive-mode, +and are able to request that certain sources are blocked or allowed. +This is known as the +.Em delta-based API . +.Pp +To block a multicast source on an existing group membership: +.Bd -literal +struct ip_mreq_source mreqs; +setsockopt(s, IPPROTO_IP, IP_BLOCK_SOURCE, &mreqs, sizeof(mreqs)); +.Ed +.Pp +where +.Fa mreqs +is the following structure: +.Bd -literal +struct ip_mreq_source { + struct in_addr imr_multiaddr; /* IP multicast address of group */ + struct in_addr imr_sourceaddr; /* IP address of source */ + struct in_addr imr_interface; /* local IP address of interface */ +} +.Ed +.Va imr_sourceaddr +should be set to the address of the source to be blocked. +.Pp +To unblock a multicast source on an existing group: +.Bd -literal +struct ip_mreq_source mreqs; +setsockopt(s, IPPROTO_IP, IP_UNBLOCK_SOURCE, &mreqs, sizeof(mreqs)); +.Ed +.Pp +The +.Dv IP_BLOCK_SOURCE +and +.Dv IP_UNBLOCK_SOURCE +options are +.Em not permitted +for inclusive-mode group memberships. +.Pp +To join a multicast group in +.Dv MCAST_INCLUDE +mode with a single source, +or add another source to an existing inclusive-mode membership: +.Bd -literal +struct ip_mreq_source mreqs; +setsockopt(s, IPPROTO_IP, IP_ADD_SOURCE_MEMBERSHIP, &mreqs, sizeof(mreqs)); +.Ed +.Pp +To leave a single source from an existing group in inclusive mode: +.Bd -literal +struct ip_mreq_source mreqs; +setsockopt(s, IPPROTO_IP, IP_DROP_SOURCE_MEMBERSHIP, &mreqs, sizeof(mreqs)); +.Ed +If this is the last accepted source for the group, the membership +will be dropped. +.Pp +The +.Dv IP_ADD_SOURCE_MEMBERSHIP +and +.Dv IP_DROP_SOURCE_MEMBERSHIP +options are +.Em not accepted +for exclusive-mode group memberships. +However, both exclusive and inclusive mode memberships +support the use of the +.Em full-state API +documented in RFC 3678. +For management of source filter lists using this API, +please refer to +.Xr sourcefilter 3 . +.Pp +The sysctl settings +.Va net.inet.ip.mcast.maxsocksrc +and +.Va net.inet.ip.mcast.maxgrpsrc +are used to specify an upper limit on the number of per-socket and per-group +source filter entries which the kernel may allocate. +.\"----------------------- +.Ss "Raw IP Sockets" +Raw +.Tn IP +sockets are connectionless, +and are normally used with the +.Xr sendto 2 +and +.Xr recvfrom 2 +calls, though the +.Xr connect 2 +call may also be used to fix the destination for future +packets (in which case the +.Xr read 2 +or +.Xr recv 2 +and +.Xr write 2 +or +.Xr send 2 +system calls may be used). +.Pp +If +.Fa proto +is 0, the default protocol +.Dv IPPROTO_RAW +is used for outgoing +packets, and only incoming packets destined for that protocol +are received. +If +.Fa proto +is non-zero, that protocol number will be used on outgoing packets +and to filter incoming packets. +.Pp +Outgoing packets automatically have an +.Tn IP +header prepended to +them (based on the destination address and the protocol +number the socket is created with), +unless the +.Dv IP_HDRINCL +option has been set. +Incoming packets are received with +.Tn IP +header and options intact, except for +.Va ip_len +and +.Va ip_off +fields converted to host byte order. +.Pp +.Dv IP_HDRINCL +indicates the complete IP header is included with the data +and may be used only with the +.Dv SOCK_RAW +type. +.Bd -literal +#include <netinet/in_systm.h> +#include <netinet/ip.h> + +int hincl = 1; /* 1 = on, 0 = off */ +setsockopt(s, IPPROTO_IP, IP_HDRINCL, &hincl, sizeof(hincl)); +.Ed +.Pp +Unlike previous +.Bx +releases, the program must set all +the fields of the IP header, including the following: +.Bd -literal +ip->ip_v = IPVERSION; +ip->ip_hl = hlen >> 2; +ip->ip_id = 0; /* 0 means kernel set appropriate value */ +ip->ip_off = offset; +.Ed +.Pp +The +.Va ip_len +and +.Va ip_off +fields +.Em must +be provided in host byte order. +All other fields must be provided in network byte order. +See +.Xr byteorder 3 +for more information on network byte order. +If the +.Va ip_id +field is set to 0 then the kernel will choose an +appropriate value. +If the header source address is set to +.Dv INADDR_ANY , +the kernel will choose an appropriate address. +.Sh ERRORS +A socket operation may fail with one of the following errors returned: +.Bl -tag -width Er +.It Bq Er EISCONN +when trying to establish a connection on a socket which +already has one, or when trying to send a datagram with the destination +address specified and the socket is already connected; +.It Bq Er ENOTCONN +when trying to send a datagram, but +no destination address is specified, and the socket has not been +connected; +.It Bq Er ENOBUFS +when the system runs out of memory for +an internal data structure; +.It Bq Er EADDRNOTAVAIL +when an attempt is made to create a +socket with a network address for which no network interface +exists. +.It Bq Er EACCES +when an attempt is made to create +a raw IP socket by a non-privileged process. +.El +.Pp +The following errors specific to +.Tn IP +may occur when setting or getting +.Tn IP +options: +.Bl -tag -width Er +.It Bq Er EINVAL +An unknown socket option name was given. +.It Bq Er EINVAL +The IP option field was improperly formed; +an option field was shorter than the minimum value +or longer than the option buffer provided. +.El +.Pp +The following errors may occur when attempting to send +.Tn IP +datagrams via a +.Dq raw socket +with the +.Dv IP_HDRINCL +option set: +.Bl -tag -width Er +.It Bq Er EINVAL +The user-supplied +.Va ip_len +field was not equal to the length of the datagram written to the socket. +.El +.Sh SEE ALSO +.Xr getsockopt 2 , +.Xr recv 2 , +.Xr send 2 , +.Xr byteorder 3 , +.Xr icmp 4 , +.Xr igmp 4 , +.Xr inet 4 , +.Xr intro 4 , +.Xr multicast 4 , +.Xr sourcefilter 3 +.Rs +.%A D. Thaler +.%A B. Fenner +.%A B. Quinn +.%T "Socket Interface Extensions for Multicast Source Filters" +.%N RFC 3678 +.%D Jan 2004 +.Re +.Sh HISTORY +The +.Nm +protocol appeared in +.Bx 4.2 . +The +.Vt ip_mreqn +structure appeared in +.Tn Linux 2.4 . +.Sh BUGS +Before +.Fx 10.0 +packets received on raw IP sockets had the +.Va ip_hl +subtracted from the +.Va ip_len +field. |
