.TH LO 4 "26 March 1982" .UC 4 .SH NAME lo \- software loopback network interface .SH SYNOPSIS .B pseudo-device loop .SH DESCRIPTION The .I loop interface is a software loopback mechanism which may be used for performance analysis, software testing, and/or local communication. By default, the loopback interface is accessible at address 127.0.0.1 (non-standard); this address may be changed with the SIOCSIFADDR ioctl. .SH DIAGNOSTICS \fBlo%d: can't handle af%d\fP. The interface was handed a message with addresses formatted in an unsuitable address family; the packet was dropped. .SH SEE ALSO intro(4N), inet(4F) .SH BUGS It should handle all address and protocol families. An approved network address should be reserved for this interface.