FreeBSD Manual Pages
LO(4) Kernel Interfaces Manual LO(4) NAME lo -- software loopback network interface SYNOPSIS device loop DESCRIPTION The loop interface is a software loopback mechanism which may be used for performance analysis, software testing, and/or local communication. As with other network interfaces, the loopback interface must have network ad- dresses assigned for each address family with which it is to be used. These addresses may be set with the appropriate ioctl(2) commands for cor- responding address families. The loopback interface should be the last in- terface configured, as protocols may use the order of configuration as an indication of priority. The loopback should never be configured first un- less no hardware interfaces exist. If the transmit checksum offload capability flag is enabled on a loopback interface, checksums will not be generated by IP, UDP, TCP, or SCTP for packets sent on the interface. If the receive checksum offload capability flag is enabled on a loopback interface, checksums will not be validated by IP, UDP, TCP, or SCTP for packets received on the interface. By default, both receive and transmit checksum flags will be enabled, in order to avoid the overhead of checksumming for local communication where data corruption is unlikely. If transmit checksum generation is disabled, then validation should also be disabled in order to avoid packets being dropped due to invalid checksums. DIAGNOSTICS lo%d: can't handle af%d. The interface was handed a message with addresses formatted in an unsuitable address family; the packet was dropped. SEE ALSO inet(4), intro(4) HISTORY The lo device appeared in 4.2BSD. The current checksum generation and val- idation avoidance policy appeared in FreeBSD 8.0. FreeBSD ports 15.1 June 23, 2024 LO(4)
NAME | SYNOPSIS | DESCRIPTION | DIAGNOSTICS | SEE ALSO | HISTORY
Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=loop&sektion=4&manpath=FreeBSD+15.1-RELEASE+and+Ports>