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Re: two private networks and a gateway



also sprach David Bishop <tech@gnuconsulting.com> [2006.08.25.2233 +0100]:
> I'm not, actually.  Hand-rolled iptables rules, actually.  Is
> there a good 'key phrase' that I can google for, that might help
> me out?

"deny by default"?

Assuming your networks are eth0/1/2 for outside/lan/eatery, then
just:

  iptables -P FORWARD DENY
  iptables -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT
  iptables -A FORWARD -m state --state INVALID -j DROP
  iptables -A FORWARD -p tcp --syn -m state --state NEW -i eth1 -o eth0 -j ACCEPT
  iptables -A FORWARD -p tcp --syn -m state --state NEW -i eth2 -o eth0 -j ACCEPT
  iptables -A FORWARD -p tcp -j DROP
  iptables -A FORWARD -i eth1 -o eth0 -j ACCEPT
  iptables -A FORWARD -i eth2 -o eth0 -j ACCEPT

done. You don't need the --syn rules and the middle drop, but
they're a good idea.

-- 
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