From: David Hough <lists@llondel.org>
To: lartc@vger.kernel.org
Subject: Re: [LARTC] possible packet forwarding or routing problem
Date: Sun, 28 Jan 2007 08:43:19 +0000 [thread overview]
Message-ID: <45BC6227.5060604@llondel.org> (raw)
In-Reply-To: <17852.5911.991893.721515@ccs.covici.com>
John covici wrote:
> Hi. I have a system with two network cards -- eth0 is a public ip
> address and eth1 is on an internal network. Now I have all the packet
> forwards enabled, and there is a route from eth1 to the internal
> network, but if a computer on the internal network sets his gateway to
> the box, he can't traceroute past the box to the internet. There
> are no iptable rules yet.
>
> Here is the routing table as produced by route.
> Destination Gateway Genmask Flags Metric Ref Use Iface
> 64.183.125.208 * 255.255.255.248 U 0 0 0 eth0
> 192.168.1.0 * 255.255.255.0 U 0 0 0 eth1
> 169.254.0.0 * 255.255.0.0 U 0 0 0 eth0
> default rrcs-64-183-125 0.0.0.0 UG 0 0 0 eth0
>
>
> What am I doing wrong here?
>
> Any assistance would be appreciated.
>
Two things spring to mind.
1. What result do you get from "cat /proc/sys/net/ipv4/ip_forward"? If
it's zero then you haven't got forwarding enabled.
2. Even if it is enabled, stuff on the LAN will head out to the big wide
world with a 192.168.1.x address on it and get eaten by any
properly-configured router outside.
To fix the first one, just "echo 1 > /proc/sys/net/ipv4/ip_forward" to
enable forwarding.
To fix the second one, you'll need a bunch of iptables rules to set up
NAT so all outbound traffic goes out using your public IP.
--
Dave
http://www.llondel.org
So many gadgets, so little time
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next prev parent reply other threads:[~2007-01-28 8:43 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-28 3:23 [LARTC] possible packet forwarding or routing problem John covici
2007-01-28 8:43 ` David Hough [this message]
2007-01-28 18:53 ` John covici
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