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>