🚀 go-pugleaf

tim@maths.tcd.ie (Timothy Murphy) writes:

>Pedro Miguel Sequeira de Justo Teixeira <pmt@hidro1.ist.utl.pt> writes:

>>> I own two UNIX machines connected via Ethernet: A and B.
>>> One system (A) is also connected to internet via SLIP (dynamic IP).
>>> How can i use the SLIP connection also on the other machine (B) ?
>>> I tried (in B) adding a default route to A, it seems that packets are sent but not
>>> received.

>>	You must recompile the kernel with the GateWaying
>>option ON (it is off by default) for Machine B.

>Have you actually done this?
>If so, please just tell us what you put in the relevant /etc files.

I think I'll post my method here so someone can try it out:

1. Assume that Machine A has a modem and will be used to dial out and
   establish SLIP connection.

2. get "ipfwadm" from ftp://ftp.xos.nl/pub/linux/ipfwadm/
   and install the program.
   For kernel version 1.3.60 or older, get ipfwadm-1.2.tar.gz
   Otherwise, get ipfwadm-2.0beta2.tar.gz. 

3. Before we setup the connection, recompile the kernel in Machine A
   with CONFIG_FIREWALL, CONFIG_IP_FORWARD, CONFIG_IP_FIREWALL, and
   CONFIG_IP_MASQUERADE set to 'y'.

4. Connect A and B via ethernet and assign an IP address to each of them.
   (In this case, A is 10.0.0.1, and B is 10.0.0.2)

5. Modify /etc/rc.d/rc.inet1 in Machine A to:
	#! /bin/sh
	HOSTNAME=`cat /etc/HOSTNAME`
	/sbin/ifconfig lo 127.0.0.1
	/sbin/route add -net 127.0.0.0
	IPADDR="10.0.0.1"
	NETMASK="255.0.0.0"
	NETWORK="10.0.0.0"
	BROADCAST="10.0.0.255"
	/sbin/ifconfig eth0 ${IPADDR} broadcast ${BROADCAST} netmask ${NETMASK}
	/sbin/route add -net ${NETWORK} netmask ${NETMASK}

6. Then, modify /etc/rc.d/rc.inet1 in Machine B to:
	#! /bin/sh
	HOSTNAME=`cat /etc/HOSTNAME`
	/sbin/ifconfig lo 127.0.0.1
	/sbin/route add -net 127.0.0.0
	IPADDR="10.0.0.2"
	NETMASK="255.0.0.0"
	NETWORK="10.0.0.0"
	BROADCAST="10.0.0.255"
	GATEWAY="10.0.0.1"
	/sbin/ifconfig eth0 ${IPADDR} broadcast ${BROADCAST} netmask ${NETMASK}
	/sbin/route add -net ${NETWORK} netmask ${NETMASK}
	/sbin/route add default gw ${GATEWAY} metric 1
	
7. Execute the 2 scripts to setup local connection.

8. Have Machine A dial out and establish SLIP connection.

9. On Machine A, execute the following commands:
	/sbin/ipfwadm -F -p accept
	/sbin/ipfwadm -F -a masquerade -S 10.0.0.1 -D 0.0.0.0/0
	/sbin/ipfwadm -F -a masquerade -S 10.0.0.2 -D 0.0.0.0/0

10. Machine B should be able to connect to the outside world at this point.
    To make it more convenient, edit /etc/resolv.conf to add a
    nameserver entry and restart inetd.

Good luck! :)


-- Henry Yeung
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