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SERIAL-IP(8)                System Manager's Manual               SERIAL-IP(8)

       serial-ip - Serial IP (SLIP or PPP) setup

       Note:  This text and the serial IP code is not finished.  Code needs to
       be added to nonamed to allow it to be used  both  with  and  without  a
       connection  to  the  Internet,  and  by  now there is a PPP program for
       standard MINIX 3 "out there" that will change everything that  is  said
       in this text.  So much to do, so little time...

       This manual page describes the MINIX 3 network setup to use serial line
       IP.  The serial IP protocol used can either be the older SLIP by  means
       of the slip(8) program, or PPP (Point-to-Point Protocol), the newer and
       better serial IP protocol implemented  by  the  ppp(8)  program.   Alas
       standard MINIX 3 only supports SLIP.

       In  the  following text all descriptions and examples will name SLIP or
       the slip program, but one may just as well  read  PPP  or  ppp.   Where
       necessary the differences will be noted.

       A typical use of the slip program is like this:

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

       The  argument  of the program, the /dev/psip2 device, is one of the so-
       called "Pseudo IP" devices that  the  MINIX  3  TCP/IP  driver  inet(8)
       offers  to  implement  a virtual network on.  On an ethernet IP packets
       are received or transmitted by the ethernet  card,  but  packets  on  a
       pseudo  IP  network  are  channeled  back to or received from a program
       running in user space, such as slip.  Standard  input  and  output  are
       used  by  slip  to  exchange  packets with another SLIP implementation.
       This is normally through an RS-232 serial line like the  second  serial
       line /dev/tty01 as used in the example above.

       If we look at the flow of data over normal ethernet then this is what a
       TCP connection between two MINIX 3 machines, telnet for instance, looks


       One-half (!) of a SLIP connection would look like this:

                                [serial line]

   Configuration for a SLIP network only
       It  is important to know that as far as inet is concerned the pseudo IP
       network is just another network,  nothing  special.   So  you  have  to
       convince  inet  that it has to send packets out over that network.  One
       does this by setting a default route that makes inet believe that there
       is a router somewhere on the pseudo-IP network.

       Assume  your machine has been given the IP address by your
       service provider.   Let's  choose  another  address  on  that  network, for instance.  (You can use the address of the SLIP gateway
       if you want to make it look  pretty,  but  it  doesn't  really  matter,
       anything  "out  there"  is ok.)  To make MINIX 3 aware of the situation
       you have to configure the pseudo IP network.  For Minix-vmd you need to
       look  for  the  if-then-else-fi  code  in  /usr/etc/rc  that  tests  if
       /etc/ should be run.  Copy the lines  in  the  else  clause  that
       starts  network  daemons  to /etc/ and add the following lines to
       make it look like this:

              # My SLIP interface address.
              ifconfig -h -n

              # Standard network daemons.
              daemonize rarpd $named irdpd rip inetd

              # Default route to the outside world.
              add_route -g

       For standard MINIX 3 one has to edit /etc/rc instead at  the  point  of
       the XXX comments.  The ifconfig goes at the first XXX, the add_route at
       the second XXX.  The result is conceptually the  same  as  the  example
       above.   The  important  thing  is  the  order: Configuration, Daemons,
       Routes.  (First  give  addresses  to  the  networks,  let  the  daemons
       meditate over the results and possibly configure more networks (rarpd),
       then add routes to the configured networks.)

       Just one thing left to do.  The system uses the first ethernet  network
       (eth0,  ip0,  tcp0, and udp0) as the default network.  With the program
       netdefault(8) you have to change  the  links  to  the  default  devices
       (eth/psip,  ip,  tcp,  and udp) to point to the first pseudo IP network
       (psip2, ip2, tcp2, and udp2):

              netdefault psip2

       In /etc/hosts list at least localhost and the name of your machine with
       its  SLIP  address.   This  way your machine will boot and know its own
       name.  Now you need to find a way to let your system know the addresses
       of other machines.  There are three ways:

              List  the  names  and addresses of any other machine you wish to
              talk to in /etc/hosts.  Drawback: This  will  quickly  become  a
              pretty long list.

              Create  an  /etc/resolv.conf that lists a nameserver at your ISP
              and (localhost).  Drawback:  With the SLIP  link  down
              it  takes  5  to 10 seconds for a name lookup to time out on the
              remote name server before the local name server is tried.

              Install the above /etc/resolv.conf when  slip  is  started,  and
              remove it when slip exits.  Drawback: Long running programs only
              read /etc/resolv.conf  at  startup,  so  they  don't  notice  it

              Run  a  real  Internet  name  daemon  from  the  named  package.
              Drawback: Nontrivial to set up.

   Configuration for a SLIP - Ethernet router (simple case)

   Configuration for a SLIP - Ethernet router (complex case)

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

       boot(8), inet(8), netdefault(8), term(1), chat(1).

       Kees J. Bot (