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(3). 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 packets 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 destination
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(4), inet(4), ip(4)