Well I just recently hooked up a DSL connection via a DSL modem that was also a router. For regular home users this DSL modem/router is probably good enough but for more complex setups it is useless. In this particular setup we had a custom built firewall. This firewall had a built in dynamic DNS service for ISP’s that rotate IP addresses. The problem however, is that the firewall was behind the DSL modem’s NAT. So it was reporting a private 192.168 number to Dyndns.
We couldn’t turn off NAT on the DSL modem unless we purchased a block of static IPs. The DSL modem, being home orientated, didn’t allow for dynamic DNS.
Fortunately dyndns offers a service to detect your public IP address. They also have an API to change your IP for dynamic DNS. Knowing this I quickly did a search on my favorite perl code repository, CPAN. Sure enough someone made a module that sends updated IP info to dyndns. Read more »