Hello, I bought a D-link DIR-300 wireless router and i can't bring NAT to work, i have an ssh and http service i need to forward to the internet. My connection is as follows:

• I have an ADSL connection, i'm using a ADSL ethernet modem connected and working, it doesnt let me put it on bridge mode.
• I have my router connected to my adsl modem through ethernet, it gets its ip through DHCP (and i'ts always the same)
• I have a desktop computer running linux with apache and openssh configured and working, it has fixed ip.
• I configured the NAT in the modem forwarding port 22 from the router ip to the internet.
• In the router i setup NAT forwarding port 22 from the desktop computer fixed ip to out there.

This setup already worked with a fonera i had before, can anyone help me with this or tell me what kind of tests do i need to do? How can i test if the router is forwarding ports correctly before the modem?