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Old 11-24-2005, 03:46 PM   #1
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NAT - pppoe problems

i have a problem and no solution... help please...
and here i go :

i have Mandrake 10 machine with a PPPoE connection to my ISP and a lan connection to my other computers

i want to make NAT so my other computers from lan to have internet access.
so i have eth1(lan): with the ip
and ppp0: with ip and it's gateway(

i have don NAT and it is working .. but not how it should...

i used iptraf to see what happens when a connection from lan is made this is happening:

the ip from lan connects to -> eth1 .. nat is done and
on ppp0 it gets out with .. ok all good until now but the problem is that it get's out but nothing comes in .. it sends the SYN flag and that's all, it doesn't receive anything back... why not???
Old 11-24-2005, 04:14 PM   #2
Registered: Nov 2003
Location: Belgium
Distribution: Slackware
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can you show the iptables rules you use? From your descriptions I don't get
enough information how you are using NAT

I'd use something like this as a start

echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE

see with
tcpdump -i ppp0


Old 11-24-2005, 04:19 PM   #3
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i use something like this

echo 1 > /proc/sys/net/ipv4/ip_forward

iptables -t nat -A POSTROUTING -o ppp0 -j SNAT --to-source


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