icmp - Internet Control Message Protocol
socket(AF_INET, SOCK_RAW, proto);
ICMP is the error and control message protocol used by IP
and the Internet
protocol family. It may be accessed through a ``raw
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
and recvfrom(2) 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.
A socket operation may fail with one of the following errors
[EISCONN] when trying to establish a connection on a
already has one, or when trying to send a
the destination address specified and the
socket is already
[ENOTCONN] when trying to send a datagram, but no destination address
is specified, and the socket hasn't
[ENOBUFS] when the system runs out of memory for an
[EADDRNOTAVAIL] when an attempt is made to create a socket
with a network
address for which no network interface
recv(2), send(2), inet(4), ip(4), netintro(4)
The icmp protocol appeared in 4.3BSD.
OpenBSD 3.6 June 5, 1993
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