projects / unix-history / blame
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|---|---|---|
| f29f3a8b MK |
1 | .\" Copyright (c) 1986 Regents of the University of California. |
| 2 | .\" All rights reserved. The Berkeley software License Agreement | |
| 3 | .\" specifies the terms and conditions for redistribution. | |
| 4 | .\" | |
| 5 | .\" @(#)icmp.4 6.1 (Berkeley) %G% | |
| 6 | .\" | |
| 7 | .TH ICMP 4P "" | |
| 8 | .UC 6 | |
| 9 | .SH NAME | |
| 10 | icmp \- Internet Control Message Protocol | |
| 11 | .SH SYNOPSIS | |
| 12 | .B #include <sys/socket.h> | |
| 13 | .br | |
| 14 | .B #include <netinet/in.h> | |
| 15 | .PP | |
| 16 | .B s = socket(AF_INET, SOCK_RAW, proto); | |
| 17 | .SH DESCRIPTION | |
| 18 | ICMP is the error and control message protocol used | |
| 19 | by IP and the Internet protocol family. It may be accessed | |
| 20 | through a \*(lqraw socket\*(rq for network monitoring | |
| 21 | and diagnostic functions. | |
| 22 | The | |
| 23 | .I proto | |
| 24 | parameter to the socket call to create an ICMP socket | |
| 25 | is obtained from | |
| 26 | .IR getprotobyname (3N). | |
| 27 | ICMP sockets are connectionless, | |
| 28 | and are normally used with the | |
| 29 | .I sendto | |
| 30 | and | |
| 31 | .I recvfrom | |
| 32 | calls, though the | |
| 33 | .IR connect (2) | |
| 34 | call may also be used to fix the destination for future | |
| 35 | packets (in which case the | |
| 36 | .IR read (2) | |
| 37 | or | |
| 38 | .IR recv (2) | |
| 39 | and | |
| 40 | .IR write (2) | |
| 41 | or | |
| 42 | .IR send (2) | |
| 43 | system calls may be used). | |
| 44 | .PP | |
| 45 | Outgoing packets automatically have an IP header prepended to | |
| 46 | them (based on the destination address). | |
| 47 | Incoming packets are received with the IP header and options intact. | |
| 48 | .SH DIAGNOSTICS | |
| 49 | A socket operation may fail with one of the following errors returned: | |
| 50 | .TP 15 | |
| 51 | [EISCONN] | |
| 52 | when trying to establish a connection on a socket which | |
| 53 | already has one, or when trying to send a datagram with the destination | |
| 54 | address specified and the socket is already connected; | |
| 55 | .TP 15 | |
| 56 | [ENOTCONN] | |
| 57 | when trying to send a datagram, but | |
| 58 | no destination address is specified, and the socket hasn't been | |
| 59 | connected; | |
| 60 | .TP 15 | |
| 61 | [ENOBUFS] | |
| 62 | when the system runs out of memory for | |
| 63 | an internal data structure; | |
| 64 | .TP 15 | |
| 65 | [EADDRNOTAVAIL] | |
| 66 | when an attempt is made to create a | |
| 67 | socket with a network address for which no network interface | |
| 68 | exists. | |
| 69 | .SH SEE ALSO | |
| 70 | send(2), recv(2), intro(4N), inet(4F), ip(4P) |