Q: How do stealth ports manage to accept a connection?

[Entropy1024]

An open port will respond to all clients attempting to connect. A
closed port will respond with a 'port closed' response. A stealth port
will not respond at all.
I have an FTP running on my PC. The port is set to stealth but people
can access it throught my router. It all works a treat and I have no
complaints.


My question is how does an FTP server running on my local LAN manages
to accept a connection to a client if the port is in stealth mode?


As I see it there is a three way handshake to initiate a connection.
Client sends a SYN packet. Server, if open, sends a SYN/ACK back.
Client responds with an ACK. Normal communication then begins.
If the port is closed the server would respnd with a SYN/RST to say port
is closed.
In stealth the server does not respond at all to the SYN request so I
can't see how any comminication is initiated.


Many thanks for any help.

[bobb]

Another terminology prob I believe.

There is no such thing as a "stealth port." There are routers/firewalls operating in stealth mode, and functioning as u described. But a client hitting an open port will get a response.

"Stealth" is mostly applied to PINGS. In the ole days, unsophisticated lurkers ping your public address to see if you are there and move on if they don't get a ping response. Stealth takes care of this by not giving a response. More sophisticated lurkers try the commonly used ports and attempt to exploit those and stealth doesn't do anything here.