diff options
| -rw-r--r-- | share/man/man4/ip.4 | 81 |
1 files changed, 48 insertions, 33 deletions
diff --git a/share/man/man4/ip.4 b/share/man/man4/ip.4 index 9a5ad54bad1..72a689f2ead 100644 --- a/share/man/man4/ip.4 +++ b/share/man/man4/ip.4 @@ -1,4 +1,4 @@ -.\" $OpenBSD: ip.4,v 1.22 2003/08/08 09:51:53 jmc Exp $ +.\" $OpenBSD: ip.4,v 1.23 2004/12/18 20:33:11 jaredy Exp $ .\" $NetBSD: ip.4,v 1.3 1994/11/30 16:22:19 jtc Exp $ .\" .\" Copyright (c) 1983, 1991, 1993 @@ -84,7 +84,7 @@ 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 +.Bd -literal -offset indent setsockopt(s, IPPROTO_IP, IP_OPTIONS, NULL, 0); .Ed .Pp @@ -100,7 +100,7 @@ and .Dv SOCK_DGRAM sockets. For example, -.Bd -literal +.Bd -literal -offset indent int tos = IPTOS_LOWDELAY; /* see <netinet/ip.h> */ setsockopt(s, IPPROTO_IP, IP_TOS, &tos, sizeof(tos)); @@ -120,27 +120,36 @@ call will return the destination address 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 +The +.Va 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 cmsghdr fields have the following values: -.Bd -literal +The +.Vt cmsghdr +fields have the following values: +.Bd -literal -offset indent cmsg_len = CMSG_LEN(sizeof(struct in_addr)) cmsg_level = IPPROTO_IP cmsg_type = IP_RECVDSTADDR .Ed .Pp -The IP_PORTRANGE +The +.Dv IP_PORTRANGE option causes the default allocation policy for when the kernel is asked to choose a free port number. Three choices are available: -.Bl -tag -width IP_PORTRANGE_DEFAULT -.It IP_PORTRANGE_DEFAULT +.Pp +.Bl -tag -width IP_PORTRANGE_DEFAULT -compact -offset indent +.It Dv IP_PORTRANGE_DEFAULT The regular range of non-reserved ports. -.It IP_PORTRANGE_HIGH +.It Dv IP_PORTRANGE_HIGH A high range, for fun. -.It IP_PORTRANGE_LOW +.It Dv IP_PORTRANGE_LOW Reserved ports; between 600 and 1023. .El .Ss "Multicast Options" @@ -159,11 +168,11 @@ The option changes the time-to-live (TTL) for outgoing multicast datagrams in order to control the scope of the multicasts: -.Bd -literal +.Bd -literal -offset indent u_char ttl; /* range: 0 to 255, default = 1 */ setsockopt(s, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)); .Ed -.sp +.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 @@ -178,12 +187,14 @@ The .Dv IP_MULTICAST_IF option overrides the default for subsequent transmissions from a given socket: -.Bd -literal +.Bd -literal -offset indent struct in_addr addr; setsockopt(s, IPPROTO_IP, IP_MULTICAST_IF, &addr, sizeof(addr)); .Ed -.sp -where "addr" is the local +.Pp +where +.Va addr +is the local .Tn IP address of the desired interface or .Dv INADDR_ANY @@ -193,7 +204,7 @@ be obtained via the .Dv SIOCGIFCONF and .Dv SIOCGIFFLAGS -ioctls. +.Xr ioctl 2 Ns 's . 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 @@ -203,11 +214,11 @@ The .Dv IP_MULTICAST_LOOP option gives the sender explicit control over whether or not subsequent datagrams are looped back: -.Bd -literal +.Bd -literal -offset indent u_char loop; /* 0 = disable, 1 = enable (default) */ setsockopt(s, IPPROTO_IP, IP_MULTICAST_LOOP, &loop, sizeof(loop)); .Ed -.sp +.Pp This option improves performance for applications that may have no more than one instance on a single host (such as a router daemon), by eliminating @@ -227,22 +238,22 @@ datagrams sent to the group. To join a multicast group, use the .Dv IP_ADD_MEMBERSHIP option: -.Bd -literal +.Bd -literal -offset indent struct ip_mreq mreq; setsockopt(s, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq)); .Ed -.sp +.Pp where .Fa mreq is the following structure: -.Bd -literal +.Bd -literal -offset indent struct ip_mreq { struct in_addr imr_multiaddr; /* multicast group to join */ struct in_addr imr_interface; /* interface to join on */ } .Ed -.sp -.Dv imr_interface +.Pp +.Va imr_interface should be .Dv INADDR_ANY @@ -260,11 +271,11 @@ Up to single socket. .Pp To drop a membership, use: -.Bd -literal +.Bd -literal -offset indent struct ip_mreq mreq; setsockopt(s, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq, sizeof(mreq)); .Ed -.sp +.Pp where .Fa mreq contains the same values as used to add the membership. @@ -320,29 +331,32 @@ indicates the complete IP header is included with the data and may be used only with the .Dv SOCK_RAW type. -.Bd -literal +.Bd -literal -offset indent #include <netinet/ip.h> int hincl = 1; /* 1 = on, 0 = off */ setsockopt(s, IPPROTO_IP, IP_HDRINCL, &hincl, sizeof(hincl)); .Ed -.sp +.Pp Unlike previous -.Tn BSD +.Bx releases, the program must set all the fields of the IP header, including the following: -.Bd -literal +.Bd -literal -offset indent ip->ip_v = IPVERSION; ip->ip_hl = hlen >> 2; ip->ip_id = 0; /* 0 means kernel set appropriate value */ ip->ip_off = htons(offset); ip->ip_len = htons(len); .Ed -.sp .5 .Pp Additionally note that starting with .Ox 2.1 , -the ip_off and ip_len fields are in network byte order. +the +.Va ip_off +and +.Va ip_len +fields are in network byte order. If the header source address is set to .Dv INADDR_ANY , the kernel will choose an appropriate address. @@ -384,6 +398,7 @@ or longer than the option buffer provided. .El .Sh SEE ALSO .Xr getsockopt 2 , +.Xr ioctl 2 , .Xr recv 2 , .Xr send 2 , .Xr icmp 4 , |