<port-on-server>, <port-on-client>, where <server-address> and
   <client-address> are the local and foreign IP addresses of the
   querying connection -- i.e., the TCP connection to the Identification
   Protocol Server.  (<port-on-server> and <port-on-client> are taken
   from the query.)

      For example:

         6193, 23 : USERID : UNIX : stjohns
         6195, 23 : ERROR : NO-USER




 
RFC 1413                Identification Protocol            February 1993


5.  RESPONSE TYPES

A response can be one of two types:

USERID

     In this case,  is a string consisting of an
     operating system name (with an optional character set
     identifier), followed by ":", followed by an
     identification string.

     The character set (if present) is separated from the
     operating system name by ",".  The character set
     identifier is used to indicate the character set of the
     identification string.  The character set identifier,
     if omitted, defaults to "US-ASCII" (see below).

     Permitted operating system names and character set
     names are specified in RFC 1340, "Assigned Numbers" or
     its successors.

     In addition to those operating system and character set
     names specified in "Assigned Numbers" there is one
     special case operating system identifier - "OTHER".

     Unless "OTHER" is specified as the operating system
     type, the server is expected to return the "normal"
     user identification of the owner of this connection.
     "Normal" in this context may be taken to mean a string
     of characters which uniquely identifies the connection
     owner such as a user identifier assigned by the system
     administrator and used by such user as a mail
     identifier, or as the "user" part of a user/password
     pair used to gain access to system resources.  When an
     operating system is specified (e.g., anything but
     "OTHER"), the user identifier is expected to be in a
     more or less immediately useful form - e.g., something
     that could be used as an argument to "finger" or as a
     mail address.

     "OTHER" indicates the identifier is an unformatted
     character string consisting of printable characters in
     the specified character set.  "OTHER" should be
     specified if the user identifier does not meet the
     constraints of the previous paragraph.  Sending an
     encrypted audit token, or returning other non-userid
     information about a user (such as the real name and
     phone number of a user from a UNIX passwd file) are




 
RFC 1413                Identification Protocol            February 1993


     both examples of when "OTHER" should be used.

     Returned user identifiers are expected to be printable
     in the character set indicated.

     The identifier is an unformatted octet string - - all
     octets are permissible EXCEPT octal 000 (NUL), 012 (LF)
     and 015 (CR).  N.B. - space characters (040) following the
     colon separator ARE part of the identifier string and
     may not be ignored. A response string is still
     terminated normally by a CR/LF.  N.B. A string may be
     printable, but is not *necessarily* printable.

ERROR

   For some reason the port owner could not be determined, 
   tells why.  The following are the permitted values of  and
   their meanings:

          INVALID-PORT

          Either the local or foreign port was improperly
          specified.  This should be returned if either or
          both of the port ids were out of range (TCP port
          numbers are from 1-65535), negative integers, reals or
          in any fashion not recognized as a non-negative