lo(7)                  UNIX System V(Internet Utilities)                  lo(7)


NAME
      lo - software loopback network interface

SYNOPSIS
      d = open ("/dev/loop", ORDWR);

DESCRIPTION
      The loopback device is a software datalink provider (interface driver)
      that returns all packets it receives to their source without involving
      any hardware devices.  It is a STREAMS device conforming to the datalink
      provider interface (DLPI).  See if(7) for a general description of
      network interfaces.

      The loopback interface is used to access Internet services on the local
      machine.  Because it is available on all machines, including those with
      no hardware network interfaces, programs can use it for guaranteed access
      to local servers.  A typical application is the comsat(1M) server which
      accepts notification of mail delivery from a local client.  The loopback
      interface is also used for performance analysis and testing.

      By convention, the name of the loopback interface is lo0, and it is
      configured with Internet address 127.0.0.1.  This address may be changed
      with the
      SIOCSIFADDR ioctl().

SEE ALSO
      comsat(1M), if(7), inet(7)



























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