How do I find out what my external IP address is?

Question

My computers are sitting behind a router/firewall. How do I programmatically find out what my external IP address is. I can use http://www.whatsmyip.org/ for ad-hoc queries,

Answer 1

If you have access to a webserver with modphp, you can roll your own:

If you don't want that to get abused, you'll have to keep it secret or add request limits.

I've been using one on my server for years.

Explicitly:

Create a file called whatismyip.php in your public_html folder in your website. It can be called anything and be anywhere in your webroot.

Add the line above, and then query your server:

curl http://example.com/whatismyip.php

for example.