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Re: blocking ports



On Fri, Jan 11, 2002 at 12:18:13AM +0100, martin f krafft wrote:
> [greg: please wrap your lines at 76 characters...]
> 
> also sprach Greg Hunt <greg@supplyedge.com> [2002.01.10.1850 +0100]:
> > The reason it reports it as filtered is if someone tries to
> > connect to a port on which you're not running a service, say
> > port 12345, your server will respond back with a TCP/IP
> > packet with the RST, ACK flags set (I know RST, I think ACK
> > too). nmap sees this as closed. If you filter something out
> > with iptables, a packet with RST flag is never sent back,
> > nmap just times out trying to connect and assumes it's
> > filtered. 
> 
> woops. discard my ICMP port unreachable thingie. (when is that
> sent???)
[snip]

UDP traffic.

-- 
Michael Wood <mwood@its.uct.ac.za>



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