TCP packets with RST flag set but **not** ACK flag OK??

Christian Seberino seberino at
Mon Apr 11 21:18:41 CEST 2005

I think RFC 793 requires TCP stacks to send RSTs if they
get packets not meant for them in some cases.  Anyone know which

For example, I think closed ports must send RSTs if they
get stuff.

This is basis for bare FIN and Xmas tree scans IIRC.

Is this right??

Even if YES, it seems a firewall could drop any RSTs that
don't have ACK set without damage right?


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