This extension checks for the external IP address currently in use (i.e: the IP address that a webmaster will see in their logs when Firefox visits their site). It displays the value on the status bar and logs the data to file along with the date and time.
There are quite a few configurable options that can be set under preferences: some of these are contradictory and so understanding the order of priority is important:
You have the option to set the logfile path manually (default is the user's home directory), the logfile name (default is the innocuous "myfile.txt"), the frequency of logging and the maximum logfile size.
You also have the option to only check and record IP address at startup. This means that if the you run an IPLogger check manually (by right-clicking on the displayed IP address and selecting "Check IP now") it will not record the result in the logfile (although any change will be displayed on the status bar).
Another option is to only record the IP address when it changes. This will apply even if run an IPLogger check manually (by right-clicking on the displayed IP address and selecting "Check IP now"). If the "only check IP at startup" preference is also checked then this takes precedence (i.e. the IP address will still not be recorded even if it has changed).
Note: This extension connects to an external site to determine your IP address. You have the option to choose between two websites which perform the checking. myipinfo.net tends to give better results when your machine is behind a proxy server.