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 3 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 stan-
dard output. A typical use is like this:
{
stty raw 115200
slip /dev/psip2 &
} </dev/tty01 >/dev/tty01
The SLIP protocol is just a very simple packet framing pro-
tocol. 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 3, 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.)
FILES
/dev/psip* Pseudo-IP devices for use by slip.
SEE ALSO
RFC-1055.
NOTES
Under MINIX 3 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>