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

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 ould 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.
Received on Tue Feb 7 20:58:29 2006