Free Joomla plugins
Klixo IP FORM plugin for Joomla 2.5 et 3.x
Klixo IP FORM plugin is a simple utility plugin to automatically record the client's IP with the POST data when a contact form is submitted.
The following line showing the IP used to submit the contact form is added at the end of the message:
Sent from: xxx.xxx.xxx.xxx
This can be useful to track IPs used to submit request through contact forms.
If you receive many spams sent from the contact form, you can install this plugin to record the IP used, to later block the corresponding IP and prevent more spam messages to be sent from this IP.
Read how to block certain IPs from accessing your site...
How to use:
Simply download and install the plugin on your site from the extensions manager. Don't forget to enable/publish the plugin in the plugin manager. That's all.