Re: newbie question: UDP is stateless ... right?

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Mr Vandeley wrote:
Hi,
Please, excuse me this newbie question, but I don't understand
correctly. For what I know, UDP connections are not statefull, so I
can't track them... right?
What I've been doing on my firewalls was explicitely accepting
incoming packets from UDP privileged ports and so accepting answers to
my UDP requests. Now I have found that if I accept RELATED,ESTABLISHED
traffic without saying anything about the protocol, UDP answers will
be accepted.
I know that this isn't a question related to Netfilter but is the only
place I know to ask about this.

thanks.

That's true if you have the correct modules installed. I ran into this problem with netbios dns packets which are UDP. I had to add nf_conntrack_netbios_ns to my /etc/modules file and then it would work. This wasn't really clear to me at the time. I thought all you needed was the iptables rule that said RELATED,ESTABLISHED. There are a bunch of those modules.

--

Knute Johnson

"The urge to save humanity is almost always a false front for the urge to rule."

  H.L. Mencken

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