portknocking question

Hi there,

I have really specific needs and wondering if somebody has written a
port knocker out there already that fits the criteria of what I am
looking for.

Portknocker capabilities:

1) User needs to telnet to specific port and/or log into a website.
2) Learns the IP address that the user is coming from in step 1.
3) Opens ssh port to specifically to the IP address grabbed in step 1
but also keeps ssh port open to statically defined IPs in
/etc/rc.firewall .
4) As soon as the user disconnects from the ssh port the IP address in
step 1 no longer can access the ssh port unless they log back in like
the procedure in step 1.

I reviewed two programs doorman and knock (found in FreeBSD
/usr/ports/security)

Doorman Review:
I am unable to figure out how to configure the ability to capture the
IP address of where the UDP packet was sent. Therefore this program
does not completely match what I am looking for, or I do not
understanding how to configure it.

Knock Review:
This is nice but still requires closing the port as a step when done.
It would be nice to automatically close the ssh port when the user
disconnects from the ssh port. Also I am not clear but I don't think
there is a way to grab the source IP address, right?

Anybody know of other programs I could check out?

Cheers,

Noah