1afe61c15SRodney W. Grimes.\" Copyright (c) 1983, 1991, 1993 2afe61c15SRodney W. Grimes.\" The Regents of the University of California. All rights reserved. 3afe61c15SRodney W. Grimes.\" 4afe61c15SRodney W. Grimes.\" Redistribution and use in source and binary forms, with or without 5afe61c15SRodney W. Grimes.\" modification, are permitted provided that the following conditions 6afe61c15SRodney W. Grimes.\" are met: 7afe61c15SRodney W. Grimes.\" 1. Redistributions of source code must retain the above copyright 8afe61c15SRodney W. Grimes.\" notice, this list of conditions and the following disclaimer. 9afe61c15SRodney W. Grimes.\" 2. Redistributions in binary form must reproduce the above copyright 10afe61c15SRodney W. Grimes.\" notice, this list of conditions and the following disclaimer in the 11afe61c15SRodney W. Grimes.\" documentation and/or other materials provided with the distribution. 12afe61c15SRodney W. Grimes.\" 3. All advertising materials mentioning features or use of this software 13afe61c15SRodney W. Grimes.\" must display the following acknowledgement: 14afe61c15SRodney W. Grimes.\" This product includes software developed by the University of 15afe61c15SRodney W. Grimes.\" California, Berkeley and its contributors. 16afe61c15SRodney W. Grimes.\" 4. Neither the name of the University nor the names of its contributors 17afe61c15SRodney W. Grimes.\" may be used to endorse or promote products derived from this software 18afe61c15SRodney W. Grimes.\" without specific prior written permission. 19afe61c15SRodney W. Grimes.\" 20afe61c15SRodney W. Grimes.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21afe61c15SRodney W. Grimes.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22afe61c15SRodney W. Grimes.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23afe61c15SRodney W. Grimes.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24afe61c15SRodney W. Grimes.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25afe61c15SRodney W. Grimes.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26afe61c15SRodney W. Grimes.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27afe61c15SRodney W. Grimes.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28afe61c15SRodney W. Grimes.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29afe61c15SRodney W. Grimes.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30afe61c15SRodney W. Grimes.\" SUCH DAMAGE. 31afe61c15SRodney W. Grimes.\" 32afe61c15SRodney W. Grimes.\" @(#)lo.4 8.1 (Berkeley) 6/5/93 33afe61c15SRodney W. Grimes.\" 34afe61c15SRodney W. Grimes.Dd June 5, 1993 35afe61c15SRodney W. Grimes.Dt LO 4 36afe61c15SRodney W. Grimes.Os BSD 4.2 37afe61c15SRodney W. Grimes.Sh NAME 38afe61c15SRodney W. Grimes.Nm lo 39afe61c15SRodney W. Grimes.Nd software loopback network interface 40afe61c15SRodney W. Grimes.Sh SYNOPSIS 41afe61c15SRodney W. Grimes.Sy pseudo-device 42afe61c15SRodney W. Grimes.Nm loop 43afe61c15SRodney W. Grimes.Sh DESCRIPTION 44afe61c15SRodney W. GrimesThe 45afe61c15SRodney W. Grimes.Nm loop 46afe61c15SRodney W. Grimesinterface is a software loopback mechanism which may be 47afe61c15SRodney W. Grimesused for performance analysis, software testing, and/or local 48afe61c15SRodney W. Grimescommunication. 49afe61c15SRodney W. GrimesAs with other network interfaces, the loopback interface must have 50afe61c15SRodney W. Grimesnetwork addresses assigned for each address family with which it is to be used. 51afe61c15SRodney W. GrimesThese addresses 52afe61c15SRodney W. Grimesmay be set or changed with the 53afe61c15SRodney W. Grimes.Dv SIOCSIFADDR 54afe61c15SRodney W. Grimes.Xr ioctl 2 . 55afe61c15SRodney W. GrimesThe loopback interface should be the last interface configured, 56afe61c15SRodney W. Grimesas protocols may use the order of configuration as an indication of priority. 57afe61c15SRodney W. GrimesThe loopback should 58afe61c15SRodney W. Grimes.Em never 59afe61c15SRodney W. Grimesbe configured first unless no hardware 60afe61c15SRodney W. Grimesinterfaces exist. 61afe61c15SRodney W. Grimes.Sh DIAGNOSTICS 62afe61c15SRodney W. Grimes.Bl -diag 63afe61c15SRodney W. Grimes.It lo%d: can't handle af%d. 64afe61c15SRodney W. GrimesThe interface was handed 65afe61c15SRodney W. Grimesa message with addresses formatted in an unsuitable address 66afe61c15SRodney W. Grimesfamily; the packet was dropped. 67afe61c15SRodney W. Grimes.El 68afe61c15SRodney W. Grimes.Sh SEE ALSO 69afe61c15SRodney W. Grimes.Xr intro 4 , 70afe61c15SRodney W. Grimes.Xr inet 4 , 71afe61c15SRodney W. Grimes.Xr ns 4 72afe61c15SRodney W. Grimes.Sh HISTORY 73afe61c15SRodney W. GrimesThe 74afe61c15SRodney W. Grimes.Nm 75afe61c15SRodney W. Grimesdevice appeared in 76afe61c15SRodney W. Grimes.Bx 4.2 . 77afe61c15SRodney W. Grimes.Sh BUGS 78afe61c15SRodney W. GrimesPrevious versions of the system enabled the loopback interface 79afe61c15SRodney W. Grimesautomatically, using a nonstandard Internet address (127.1). 80afe61c15SRodney W. GrimesUse of that address is now discouraged; a reserved host address 81afe61c15SRodney W. Grimesfor the local network should be used instead. 82