SLIP(8)

NAME
slip - Serial Line IP

SYNOPSIS
slip pseudo-ip-device

DESCRIPTION
The slip program implements an Internet network connection over a bidirectional 8-bit transport, usually a serial line. The protocol used for this connection is the Serial Line Internet Protocol, SLIP for short.

The pseudo-ip-device argument names one of the /dev/psip* devices that is offered by the Minix TCP/IP driver inet(8). The slip program reads IP packets from standard input and writes them to the pseudo IP device, and reads packets from the pseudo IP device and writes them to standard output. A typical use is like this:

    slip /dev/psip2 </dev/tty01 >/dev/tty01

The SLIP protocol is just a very simple packet framing protocol. It defines two characters as markers on a byte stream to frame packets. SLIP does not implement any higher level addressing, error detection, or compression. Thanks to its simplicity it can be used under Minix, any other system would prefer to use the Point-to-Point protocol: PPP.

The SLIP packet framing protocol as defined in RFC-1055 is as follows:

-   Packets are delimited by an END character, octal 300. END is often send at the start of a packet too to reset the logic of the receiver, so that random noise isn't added to the beginning of a packet.

-   An ESC character (octal 333) is used to escape any END or ESC characters that may occur in an IP packet. END and ESC are changed to ESC 334 and ESC 335 in the data stream. (Note that END doesn't occur within the data stream at all by escaping it this way, making finding the framing END easier.)

The manual page serial-ip(8) describes how to configure the Minix network devices to be used with a serial IP connection.

FILES

/dev/psip*
    Pseudo-IP devices for use by slip.

SEE ALSO
ppp(8), serial-ip(8).
RFC-1055.

NOTES
Under Minix slip forks in two to handle the two data streams in or out of the serial line. Under Minix-vmd it uses asynchronous I/O to handle the two streams within one program.

AUTHOR
Kees J. Bot (kjb@cs.vu.nl)