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Re: [LARTC] possible packet forwarding or routing problem

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Subject: Re: [LARTC] possible packet forwarding or routing problem
From: John covici <covici@ccs.covici.com>
Date: Sun, 28 Jan 2007 13:53:43 -0500
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on Sunday 01/28/2007 David Hough(lists@llondel.org) wrote
 > 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
 > _______________________________________________
 > LARTC mailing list
 > LARTC@mailman.ds9a.nl
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-- 
Your life is like a penny.  You're going to lose it.  The question is:
How do
you spend it?

         John Covici
         covici@ccs.covici.com
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