[Snort-users] How does a reject rule work?

Phil Wood cpw at ...440...
Tue Apr 29 10:58:42 EDT 2008


Read RFC 792 to understand the ICMP Destination Unreachable Message.
"bahamin" not talking about ICMP ports its talking about the messages
sent by hosts using ICMP to tell the sender of something that is not
"reachable" on the recipients computer (such as a port).

One place to find the RFC:

ftp://ftp.rfc-editor.org/in-notes/rfc792.txt

On Tue, 2008-04-29 at 09:02 -0400, Todd Wease wrote:
> You're not going to get 'Destination port unreachable' with ICMP packets
> (they address no port).  Try with UDP or TCP packets and rule.
> 
> 
> bahamin takhtaei wrote:
> > Hi,
> > 
> > I wrote an icmp rule with "reject" action and
> > test it by echo request packets (ping), but
> > I didn't catch any "Destination port unreachable"
> > message on the test system. It seems that my
> > "reject" rule works as a "drop" rule only! Now
> > please tell me What do I to fix this problem?
> > 
> > 
> > Thanks,
> > Bahamin
> > 
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-- 
C. Philip Wood, Int. D.                                                                     
Senior Member of the Internet
Los Alamos National Laboratory
Key fingerprint: 2BB7 A990 44F5 EF4B 4E35  8635 1205 97D3 F6D8 7F39
E-mail: cpw at ...440..., cornett at ...1649...
Phone: 510 667-2598
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