[TriLUG] ip_forward questions
mhrivnak at triad.rr.com
Mon Sep 29 18:31:41 EDT 2003
I use the following iptables rules to forward a port for VNC. You may
notice that the guide you are reading is over three years old, written when
ipchains was used. It has been replaces with iptables, which I consider
more complicated but amazingly powerful. There are a number of kernel
options related to the functionality of iptables.
iptables -A FORWARD -i eth0 -o eth1 -p tcp --dport 5900 -j ACCEPT
iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 5900 -j DNAT /
I suggest chewing on "man iptables" for a while. Looking at examples helps
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---------- Original Message -----------
From: Mike Mueller <linux-support at earthlink.net>
To: trilug at trilug.org
Sent: Mon, 29 Sep 2003 17:02:49 -0400
Subject: [TriLUG] ip_forward questions
> CONFIG_IP_FORWARD no longer exists in .config for 2.4.18+ and
> 2.2.19+. IP forwarding is now controlled with
> This exerpt from "Linux Dialin Server Setup Guide"
> (http://www.swcp.com/~jgentry/pers.html) confuses me because it
> suggests ip_forwarding is still an individual kernel option. (I
> don't think this is the case however because searching on "FORWARD"
> in /usr/src/linux/.config is fruitless)
> If you intend to use your dialin server as a gateway for dialin
> clients, you will need support for IP forwarding in your kernel.
> Unless you did a custom install of the OS, IP forwarding is probably
> supported. To check, see if the file /proc/sys/net/ipv4/ip_forward
> exists. If it does, IP forwarding is supported in your kernel.
> Can anybody explain the apparent change and why it was put into
> Mike Mueller
> 324881 (08/20/2003)
> Make clockwise circles with your right foot.
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