sl(4) [netbsd man page]

SL(4)							   BSD Kernel Interfaces Manual 						     SL(4)

NAME

     sl -- Serial Line IP (SLIP) network interface

SYNOPSIS

     pseudo-device sl

DESCRIPTION

     The sl interface allows asynchronous serial lines to be used as IPv4 network interfaces using the SLIP protocol.

     To use the sl interface, the administrator must first create the interface and assign a tty line to it.  The sl interface is created using
     the ifconfig(8) create subcommand, and slattach(8) is used to assign a tty line to the interface.	Once the interface is attached, network
     source and destination addresses and other parameters are configured via ifconfig(8).

     The sl interface can use Van Jacobson TCP header compression and ICMP filtering.  The following flags to ifconfig(8) control these properties
     of a SLIP link:

     link0	   Turn on Van Jacobson header compression.

     -link0	   Turn off header compression. (default)

     link1	   Don't pass through ICMP packets.

     -link1	   Do pass through ICMP packets. (default)

     link2	   If a packet with a compressed header is received, automatically enable compression of outgoing packets. (default)

     -link2	   Don't auto-enable compression.

DIAGNOSTICS

     sl%d: af%d not supported .  The interface was handed a message with addresses formatted in an unsuitable address family; the packet was
     dropped.

SEE ALSO

     inet(4), intro(4), ppp(4), strip(4), ifconfig(8), slattach(8), sliplogin(8), slstats(8)

     J. Romkey, A Nonstandard for Transmission of IP Datagrams over Serial Lines: SLIP, RFC, 1055, June 1988.

     Van Jacobson, Compressing TCP/IP Headers for Low-Speed Serial Links, RFC, 1144, February 1990.

HISTORY

     The sl device appeared in NetBSD 1.0.

BUGS

     SLIP can only transmit IPv4 packets between preconfigured hosts on an asynchronous serial link.  It has no provision for address negotiation,
     carriage of additional protocols (e.g.  XNS, AppleTalk, DECNET), and is not designed for synchronous serial links.  This is why SLIP has been
     superseded by the Point-to-Point Protocol (PPP), which does all of those things, and much more.

BSD
								   July 9, 2006 							       BSD

Check Out this Related Man Page

LO(4)                                                      BSD 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 addresses assigned for each address family with which it is to be
     used.  These addresses may be set or changed with the SIOCSIFADDR ioctl(2).  The loopback interface should be the last interface configured,
     as protocols may use the order of configuration as an indication of priority.  The loopback should never be configured first unless no hard-
     ware interfaces exist.

     If the transmit checksum offload capability flag is enabled on a loopback interface, checksums will not be generated by IP, UDP, or TCP 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, or TCP 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 validation avoidance policy appeared in FreeBSD 8.0.

BSD                                                               March 15, 2009                                                               BSD

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sl(4) [netbsd man page]

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