[unisog] Port 0

Bob Johnson bob89 at eng.ufl.edu
Tue Nov 1 21:41:07 GMT 2005

On Thursday 27 October 2005 09:59 am, Christensen, Eric wrote:
> I was reviewing my firewall logs this morning and found a few packets
> going to and from port 0.  Apparently they were ICMP packets.  I think
> that is probably legitimate but I'm thinking that many computers might
> accept these packets thinking they are legit when they are really
> attacks.  If they are just ICMP packets you could just block them. 
> Right?

No, this is a common misconception.  Some ICMP packets are important for 
normal network operation (or more accurately, for normal abnormal 
operation!).  I have a discussion at 
http://www.eng.ufl.edu/bobj/firewall-icmp.html.  Forgive the formatting, it 
was automatically translated from another format.

- Bob

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