I need to get to my home network from the outside. The home network is connected to the world via a cable modem service by RCN. Yes it is firewalled. To get to some of my services I use dyndns.org's free dynamic DNS service. You sign up and give it your cable modem's external IP address, and create a DNS name like myname.dyndns.org. The service will point that name to the IP address that you entered. There are two catches -- your cable service may change the IP address of your modem (dynamic IP, get it ?) on you periodically. The dyndns.org service also will delete your account (after all, it is free) after two weeks of no updates. The solution ? You need some client software on your system to periodically update the IP address entry at dyndns.org. I run ipcheck.py on Linux via a cron job.