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-   -   iptables - strange behaviour of nat?? (http://www.linuxquestions.org/questions/linux-networking-3/iptables-strange-behaviour-of-nat-243539/)

shacky 10-16-2004 04:11 PM

iptables - strange behaviour of nat??
 
hi :)
I set iptables masquerade on "server".... clients has good gateway, and they can ping machines outside nat, dns works too, but nothing else :( tcp and udp packets goes to server and... are dropped???

I couldn't public dump of tcpdump because I haven't got 5 posts(there are urls) :( So if someone would like to help me it's there: cobra<dot>eu<dot>org/tcpdump.txt

n3tw0rk 10-16-2004 07:29 PM

have you read the IP masquerading HOWTO? If not then visit http://en.tldp.org/HOWTO/IP-Masquerade-HOWTO/ . Make sure that you use a simple firewall script such as http://en.tldp.org/HOWTO/IP-Masquera...FIREWALL-2.4.X the first time. Use iptables -nvL to see which policy is in action. I hope that helps!

shacky 10-17-2004 10:44 AM

thx
it wasn't my first masquerade.... but first where i had to change TTL target ;) this provider checks if TTL is diffrent then 64(linux), 255(windows)..... masquerade decreases TTL by one, so my masq has been sending 63, 254... :(

iptables -t mangle -A PREROUTING -i eth1 -j TTL --ttl-set 64

and everything is ok ;)
you have to patch kernel with patch-o-matic from netfilter.org


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