NxFilter is a freeware project (only for non-commercial usage) that offers a DNS filtering program to system administrators who are looking for a platform-independent solution to filter and monitor Internet activity in their network.
With NxFilter, you will be able to detect and block malware or botnets, thanks to its DNS packet inspection functionality. It is an application written in the Java programming language that supports Linux, Microsoft Windows and Apple Macintosh operating systems.
Key features include Active Directory integration, group or user based policy assignment, dual policy setup for free-time and work-time, quota time, phishing protection, ability to block sites by domain categories, an unlimited number of custom categories, as well as unlimited user and group creation.
In addition, it boasts a built-in graphical user interface (GUI) that allows user to configure some functions, email-based notifications, four types of authentication, including LDAP (Lightweight Directory Access Protocol) authentication, password and IP-based ones.
The application also comes with embedded web server and database, support for internationalized domain names, reporting, dashboard, ability to export the logs to syslog, Single Sign-On (SSO) with Active Directory, and DNS query log search.
When using NxFilter, it is also possible to use the local DNS cache to accelerate your network connection. Furthermore, it provides load balancing and fail-safe with clustering, bandwidth control, remote user filtering, and support for urlblacklist and shallalist.
Another important feature is the blacklist and whitelist functionality, which is based on keyword searching and domain matching. Its modern web-based interface includes numerous functions and a demo that can be found at http://demo.nxfilter.org/admin.
Summing up, NxFilter is a decent web filtering application designed from the ground up to be portable and easy to use. However, on some GNU/Linux platforms it fails to even start, simply because of its Java Runtime Environment requirements. Visit the official "Install NxFilter on Unix" tutorial for more details.