The Fugue

“What is my IP?” A frequent question while we all remain under the oppression of NAT. Of course most of you are familiar with whatismyip.com and friends, but did you know you can do the same thing yourself very easily? All you need is a webserver (across the NAT in question, of course).

Here’s a CGI version:

#!/bin/sh
echo "Content-type: text/plain"
echo
echo $REMOTE_ADDR

If CGI is a pain but you have PHP:

<?php
  header("Content-type: text/plain");
  echo $_SERVER['REMOTE_ADDR'];
?>

Both of these are suitable for scripting, e.g.

#!/bin/bash
URL=http://fugal.net/ip.cgi
echo Your IP address is `curl -s "$URL"`