ICMP(ADMP)                                 UNIX System V



     Name
          icmp - Internet Control Message Protocol


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

          s = socket(AFINET, SOCKRAW, proto);


     Description
          ICMP is the error and control message (or  device)  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  .  [See getprotoent(SLIB).] ICMP sockets are
          connectionless, and are normally used with  the  sendto  and
          recvfrom  calls;  the  connect(SSC) call may also be used to
          fix the destination for future packets (in  which  case  the
          read(S)  or recv(SSC) and write(S) or send(SSC) 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  that  already has one, or when trying
                         to  send  a  datagram  with  the  destination
                         address  specified  and  the  socket  already
                         connected;

     [ENOTCONN]
                         when  trying  to  send  a  datagram,  but  no
                         destination  address  is  specified,  and the
                         socket has not been connected;

     [ENOSR]
                         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.


     Files
          /dev/inet/icmp


     See Also
          send(SSC), recv(SSC), intro(ADMP), inet(ADMP), ip(ADMP).


     (printed 8/17/89)                                  ICMP(ADMP)