icmp

 

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 Protocols                                                icmp(7P)
 
 
 


NAME
      icmp, ICMP - Internet Control Message Protocol
 


SYNOPSIS
      #include <sys/socket.h>
      #include <netinet/in.h>
      #include <netinet/ip_icmp.h>
      s = socket(AF_INET, SOCK_RAW, proto);
      t = t_open("/dev/icmp", O_RDWR);
 


DESCRIPTION
      ICMP is the error and control message protocol used  by  the
      Internet protocol family. It is used by the kernel to handle
      and report errors in protocol processing.  It  may  also  be
      accessed by programs using the socket interface or the Tran-
      sport Level Interface ("TLI")  for  network  monitoring  and
      diagnostic functions. When used with the socket interface, a
      "raw socket" type is used. The  protocol  number  for  ICMP,
      used  in  the  proto  parameter  to  the socket call, can be
      obtained from getprotobyname(3SOCKET). ICMP file descriptors
      and  sockets  are connectionless, and are normally used with
      the t_sndudata / t_rcvudata and the  sendto()  /  recvfrom()
      calls.
 
      Outgoing packets automatically  have  an  Internet  Protocol
      ("IP")  header  prepended to them. Incoming packets are pro-
      vided to the user with the IP header and options intact.
 
      ICMP is an datagram protocol layered above IP.  It  is  used
      internally  by the protcol code for various purposes includ-
      ing  routing,  fault  isolation,  and  congestion   control.
      Receipt  of  an ICMP "redirect" message will add a new entry
      in the routing table, or modify an existing one.  ICMP  mes-
      sages are routinely sent by the protocol code. Received ICMP
      messages may be reflected back to users of higher-level pro-
      tocols  such  as  TCP  or  UDP  as error returns from system
      calls. A copy of all ICMP message received by the system  is
      provided  to  every  holder  of  an  open ICMP socket or TLI
      descriptor.
 


SEE ALSO
      getprotobyname(3SOCKET),    recv(3SOCKET),    send(3SOCKET),
      t_rcvudata(3NSL),    t_sndudata(3NSL),   inet(7P),   ip(7P),
      routing(7P)
 
      Postel, Jon,  Internet  Control  Message  Protocol  -  DARPA
      Internet  Program  Protocol  Specification, RFC 792, Network
      Information Center, SRI International, Menlo  Park,  Calif.,
      September 1981.
 


DIAGNOSTICS
 
 
 
 
 SunOS 5.8            Last change: 3 Jul 1990                    1
 
 
 
 
 
 
 Protocols                                                icmp(7P)
 
 
 
      A socket operation may fail with one of the following errors
      returned:
 
      EISCONN
            An attempt was made 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
            An attempt was made to send a datagram, but no  desti-
            nation  address  is  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.
 


NOTES
      Replies to ICMP "echo" messages which are source routed  are
      not  sent  back  using inverted source routes, but rather go
      back through the normal routing mechanisms.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 SunOS 5.8            Last change: 3 Jul 1990                    2
 
 
 

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