Question

linux -one NIC - NAT

Asked by: Fahim-M

I have a Redhat linux 9.0 server - also got an ADSL connection connected -

I have only one network card on the server - i need to install NAT on the server so that the internal clients can have the server as the default gateway and can reach the internet - the internal ip range is 192.168.0.* - how do i use iptables to do this or do i have to use another script

Many thanks in advance guys... always a help :)

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Asked On
2004-12-03 at 22:47:45ID21230139
Topic

Linux Networking

Participating Experts
3
Points
205
Comments
9

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Answers

 

by: rindiPosted on 2004-12-04 at 02:33:05ID: 12743469

Get a second NIC for the server, then use shorewall. I don't think there is a ggod way to do what you want with just one nic.

 

by: Fahim-MPosted on 2004-12-04 at 06:06:14ID: 12744167

i got no second NIC :( .. plz help

 

by: rindiPosted on 2004-12-04 at 06:29:08ID: 12744234

Go buy one, they only cost around $10.--

 

by: wesly_chenPosted on 2004-12-04 at 07:12:56ID: 12744359

> i got no second NIC :( .. plz help
No 2 NICs, no NAT. That's requirement for NAT (router).

Wesly

 

by: Fahim-MPosted on 2004-12-04 at 12:21:17ID: 12745284

so theres absolutely no way ... :

 

by: wesly_chenPosted on 2004-12-04 at 12:58:07ID: 12745381

Anything wrong with another NIC? That's the solution for NAT.

Wesly

 

by: martapPosted on 2004-12-05 at 12:56:51ID: 12749640


It can be done with one NIC not recommendable, but can be done...

You can have virtual interfaces..

eth0 (internal range)
eth0:1 (internet)

and then configure your iptables between these 2 interfaces.

 

by: Fahim-MPosted on 2004-12-06 at 01:43:46ID: 12752470

ok guys got two  NICS :) - thanks for the comment martap - :) - now how do i do it :)

 

by: wesly_chenPosted on 2004-12-06 at 18:30:00ID: 12760397

Hi,

  This might help:

iptables -t nat -A PREROUTING -i eth0 -p tcp  -j DNAT   --to <Public_ip_2>
iptables        -A INPUT      -i eth0 -p tcp  -j ACCEPT  -d  <Public_ip_2>
iptables        -A INPUT      -i eth1 -j ACCEPT
echo 1 > /proc/sys/net/ipv4/ip_forward
iptables        -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT

Please do "man iptables" for more information

Wesly

20120131-EE-VQP-002

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