a new question on iptables and port 5353

[Frantisek Hanzlik]

Paul Allen Newell wrote:
> To all:
> 
> With help from Craig and Reindl, I've understood what happens with the
> automated entry of port 631 for udp/tcp and how to rewrite to not make
> it a world access (in/out) rule. Waiting for next install of F16 to test
> when and how the automated entry happens.
> 
> I saw this entry in iptables but decided to wait on asking about it
> until I understood port 631:
> +++
> -A INPUT -m state --state NEW -m udp -p udp --dport 5353 -d 224.0.0.251
> -j ACCEPT
> +++
> 
> I know I didn't add it. From what I can tell, port 224.0.0.251 has to do
> with "multicast DNS". Everything I see about port 5353 involves Macs.
> 
> My gut says that, since I have no Macs, this must be something that got
> added when I installed my printer and that CUPS/whatever did a blanket
> automated entry to cover any issues if I had a Mac on my net.
> 
> Can anyone tell me if I am right (or, if not, what it really is). I feel
> I should be able to blast it from iptables without having any problems,
> but want some better minds to comment first.
> 
> Thanks,
> Paul

http://www.redhat.com/archives/rhl-list/2007-November/msg00389.html

and - UDP is stateless, thus no "-m state --state NEW".