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icmp(7)
NAME
  icmp - Internet Control Message Protocol

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

  s = socket(AF_INET, SOCK_RAW, proto);

DESCRIPTION
  The Internet Control Message Protocol (ICMP) is the error and control
  message protocol used by the Internet Protocol (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 the getprotobyname()
  function.  ICMP sockets are connectionless, and are normally used with the
  sendto() and recvfrom() functions.  The connect() function may also be used
  to fix the destination for future packets, in which case the read() or
  recv() and write() or send() functions may be used.

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

ERRORS
  If a socket operation fails, errno may be set to one of the following
  values:

  [EISCONN] The socket is already connected.  This error occurs when trying
	    to establish connection on a socket or when trying to send a
	    datagram with the destination address specified.

  [ENOTCONN]
	    The destination address of a datagram was not specified, and the
	    socket has not been connected.

  [ENOBUFS] The system ran out of memory for an internal data structure.

  [EADDRNOTAVAIL]
	    An attempt was made to create a socket with a network address for
	    which no network interface exists.

RELATED INFORMATION
  Functions: send(2), recv(2)

  Files: netintro(7), inet(7), ip(7)