Administering name-to-address mapping

The tcpip.so library

The routines in this dynamic library create addresses from the hosts(4tcp) TCP/IP package. The hosts file contains the machine's IP address as the first field followed by any number of machine names separated by white space. For example:

   #IP address          machine name(s)        (optional comment)
   #
   192.11.108.01        bilbo
   192.11.108.16        elvis                  # Located at Graceland
   192.11.103.2         weeble wombat

The services file contains three fields: ``service name'', ``port/protocol'' (with one of two protocol specifications either ``tcp'' or ``udp''), and ``aliases''. For example:

   #service name     port/protocol     aliases
   #
   netstat           15/tcp
   netstat           15/udp
   time              37/tcp            mail
   time              37/udp            mail
   nntp              119/tcp           usenet readnews untp

For an application to use this library to request the address of a service on a particular host, the host name must appear in the /etc/hosts file and the service name must appear in the /etc/services file. If one or the other does not appear, an error will be returned by the name-to-address mapping routines.