I followed the instructions in the June 1998 issue of Linux Journal. Thanks to Loris Renggli.

This is a network connection through the serial port. Once the SLIP is up and running,
you will be able to use telnet, ftp, rcp, or lynx.

requirements:

special serial cable or connector - "null modem"

two computers - root access on both
free serial ports on both machines
tcp/ip utilities:
route
ifconfig
ping
etc/services
etc/hosts
etc/protocals
general utilities
/bin/telnet
/bin/sh
slip compiled into the Linux kernel, or
slip functionality thru modules- modprobe, slip.o

My case:

1. 386sx - 30 mhz - 2 meg running Small Linux 0.5.0 -standalone - kernel 1.2.11
2. 386sx 50 mhz - 4 meg running Small Linux 0.5.0 - standalone - kernel 2.0.0

My steps:

1. setup etc files on both computers
protocals
services

hosts - on 386 50mhz computer (sag)
192.168.93.1 localhost
192.168.93.1 sag
192.168.93.2 baby

hosts - on 386 30hmz computer (baby)
192.168.93.2 locahost
192.168.93.2 baby
192.168.93.1 sag

2. setup slip startup script files
slip-on.sh on machine 1 and
slip-on.sh on machine 2 (see bottom of document for examples)


3. setup cable between the two computer
both my machines have two serial ports
port # 0 is 0x3F8 irq 4 on both
restart both machines

4. run slip-on.sh on both machines

5. test network settings and connection
route should print out localhost and other machine
ifconfig should printout lo and sl0 address
then using ping should get response from remote computer for example: ping sag ping baby

6. have deamons running or available on each machine
inetd
in.telnetd
in.ftpd

7. enjoy it!
telnet should log in to remote
ftp can be used to transfer files

8. setup NFS for mouting network drives


slip-on.sh on machine 2 - sag:
#!/bin/sh
slattach -s 57600 -p slip /dev/cua0 &
sleep 1
/sbin/ifconfig s10 sag pointopoint baby up
/sbin/route add sag dev lo
/sbin/route add baby dev s10


slip-on.sh on machine 1 - baby:
#!/bin/sh
slattach -s 57600 -p slip /dev/cua0 &
sleep 1
/sbin/ifconfig s10 baby pointopoint sag up
/sbin/route add baby dev lo
/sbin/route add sag dev s10

revision history: rev 2 - 1999-8-22 corrected some typos
rev 1 - 1999-8-19 first draft - based on plip document