LAN Messenger is a free and open source cross-platform instant messaging application for communication over a local network.
http://lanmsngr.sourceforge.net/downloads.phpAbout LAN Messenger
LAN Messenger is a free and open source cross-platform instant messaging application for communication over a local network. It does not require a server. A number of useful features including event notifications, file transfer and message logging are provided.
Currently the platforms supported are Windows, Mac and Linux.
Key features
Instant messaging
Connect and chat with users on your network.
Secure messaging for privacy
All messages are protected by AES encryption with RSA as the key exchange mechanism.
Broadcast messages
Send notifications to all users or specified users.
File transfer
Exchange files with others easily.
Organize contacts
Arrange your contacts into groups for easier management.
Message logging
Past conversations are logged and can be retrieved at any time.
Serverless architecture
A server does not need to be set up on the network for LAN Messenger to work.
No internet connection required
As the name suggests, LAN Messenger works inside the local network and does not require internet access. This helps to minimize external threats.
Multi-language user interface
You can select the language for the user interface.
Cross-platform support
All the features of this application are supported on Windows, Mac and Linux. The interface is fully integrated with the native environment of each platform.
http://lanmsngr.sourceforge.net/
http://lanmsngr.sourceforge.net/downloads.php