2.11BSD#431 - /usr/man/cat4/icmp.0

ICMP(4P)	    UNIX Programmer's Manual		 ICMP(4P)


NAME
     icmp - Internet Control Message Protocol

SYNOPSIS
     #include <sys/socket.h>
     #include <netinet/in.h>

     s = socket(AF_INET, SOCK_RAW, proto);

DESCRIPTION
     ICMP is the error and control message protocol used by IP
     and the Internet protocol family.	It may be accessed
     through a "raw socket" for network monitoring and diagnostic
     functions.  The proto parameter to the socket call to create
     an ICMP socket is obtained from getprotobyname(3N).  ICMP
     sockets are connectionless, and are normally used with the
     sendto and recvfrom calls, though the connect(2) call may
     also be used to fix the destination for future packets (in
     which case the read(2) or recv(2) and write(2) or send(2)
     system calls may be used).

     Outgoing packets automatically have an IP header prepended
     to them (based on the destination address).  Incoming pack-
     ets are received with the IP header and options intact.

DIAGNOSTICS
     A socket operation may fail with one of the following errors
     returned:

     [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;

     [ENOTCONN]     when trying to send a datagram, but no desti-
		    nation address is specified, and the socket
		    hasn't been connected;

     [ENOBUFS]	    when the system runs out of memory for an
		    internal data structure;

     [EADDRNOTAVAIL]
		    when an attempt is made to create a socket
		    with a network address for which no network
		    interface exists.

SEE ALSO
     send(2), recv(2), intro(4N), inet(4F), ip(4P)


Printed 11/26/99	  May 16, 1986				1