Re[2]: how nmap can know my firewalled servers ?

[Thierry Zoller <Thierry () Zoller lu>]

Dear Arturas Zalenekas,

AZ> How does TCP protocol work !? How should it replay, e.g. to a closed port
AZ> !? With ICMP packet !?
Lots of Packetfilters answer with ICMP Administravtively Prohibited,
sometimes also leaking their internal IP address by the way..  It is a
common way to respond every IP stack I know about will understand that
message.

AZ> No, it has to answer with an RST.
Answering with ICMP is fine, possible and in the wild.

-- 
http://secdev.zoller.lu
Thierry Zoller
Fingerprint : 5D84 BFDC CD36 A951 2C45  2E57 28B3 75DD 0AC6 F1C7


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