Filtered Ports

On a security scan what is a filtered port?  If a port the host is listening on, should the port be closed?
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aadihConnect With a Mentor Commented:
Open ports.
aadihConnect With a Mentor Commented:

(1) Open Port:  If you send a SYN to an open port, you would expect to receive a

(2) Closed Port: If you send a SYN to a closed port, it will respond back with a RST.

(3) Filtered Port: Presumably, the host is behind some sort of firewall.  Here, the
packet is simply dropped and you receive no response (not even a RST).

For a listening port (a little long) look here: >
Jack_son_Author Commented:
Great, thanks for the information.  Should filtered ports be investigated closer or are the open ports the primary risk?
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