RE: iptables REJECT types for UDP (if any)

At 18:01 16/11/02 +0100, Miguel Angel Rodríguez Jódar wrote:

>> using -j DROP as a target, what I want to know is what types

Not true,

While UDP doesn't have RST, you can still send an ICMP destination port unreachable error, which has the same effect.

In fact, if you use TCPDUMP I think you'll find that the REJECT rule for both UDP *and* TCP uses ICMP destination port unreachables.

This makes it possible to tell the difference with a scanner between a TCP port which is really closed (sends a RST) and a TCP port that is firewalled with REJECT. (Sends an ICMP DEST UNREACH)

Regards,
Simon Received on Thu Nov 21 20:30:27 2002

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