pppoe with NAT not working
sbernard at nerim.net
Fri Oct 21 19:13:11 CEST 2005
Sébastien Bernard a écrit :
>I got a real big headache.
>My DSL provider a few ago upgraded my line and for this changed the BAS my
>box used to connect with.
>I had to reconfigure the ppp configuration.
>Before, I was using :
>pty "/usr/sbin/pppoe -I eth0 -T 80 -m 1452"
>It ceased working.
>The new configuration is using the rp-pppoe.so plugin as :
>Since this modification, I'm not able to do any NAT or MASQUERADE with my
>My network architecture is :
>Private lan (192.168.x.x) => GW (public fixed address) => DSl Modem =>
>When any machine on the private LAN try make a connection to an outside
>address, the connection made is ok.
>The three-way handshake is OK with the packets correctly NATED.
>When the outside peer tries to send data to the internal peer, the Gateway
>sends a reset back to it without breaking the connection inside of course.
>It looks like the netfilters didn't accept the incoming packets with
>payload as part of the nated connection.
>I had a look to the ip_conntrak connection and the faulty connection is
>correctly tracked, with an entry.
>I don't really understand what is happenning.
>The configuration is nothing special and could resumed as :
>iptables -t nat -A POSTROUTING -o ppp0 -j SNAT --to-source <public address>
>This was working before and I didn't touch anything to the configuration
>but the public address that changed when I moved to a speedier DSL line.
>If anyone could propose an explaination ...
I figured out the problem.
NAT is not working with the rp-pppoe.so plugin.
I moved back to the
pty "/usr/sbin/pppoe -I eth0 -T 80 -m 1452"
Which worked now (go figure...).
And NAT is working again.
Any reason for this ?
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