NAME

lo − software loopback network interface

DESCRIPTION

The loopback device is a psuedo device provided by IP for use in intra-machine TCP/IP communication. 

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.  The interface can be brought up and down using the ifconfig(1M) command but the address cannot be changed. 

SEE ALSO

comsat(1M), ifconfig(1M), if(7), inet(7)

  —  Internet Utilities