lo(7)                  DEVICES AND MODULES                  lo(7)



NAME
     lo - software loopback network interface

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

DESCRIPTION
     The loopback device is a software datalink provider  (inter-
     face  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  inter-
     faces,  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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