Development of l7-filter has moved to the Clear Foundation. These pages are out of date, but will remain as a historical record.

Application Layer Packet Classifier for Linux

7 logo

L7-filter is a classifier for Linux's Netfilter that identifies packets based on application layer data. It can classify packets as Kazaa, HTTP, Jabber, Citrix, Bittorrent, FTP, Gnucleus, eDonkey2000, etc., regardless of port. It complements existing classifiers that match on IP address, port numbers and so on.

Our intent is for l7-filter to be used in conjunction with Linux QoS to do bandwith arbitration ("packet shaping") or traffic accounting.

To download, see our Sourceforge project page


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Absolutely essential reads

Before asking questions on the mailing list, read these

l7-filter development docs

Feature overview

More documentation

How can I help?

Contact us

Submissions, complaints, criticism, praise, comments? (you must subscribe first). Need help? l7-filter-users(a) Alternatively, bug reports, requests for features, and patches may be submitted through our Sourceforge page.

Related software

Front-ends that support l7-filter (not tested by us)

Similar (open source/partially open source) projects


The original coders were Justin Levandoski, Ethan Sommer, and Matthew Strait, with support from Sebastian Celis, Andy Exley and Lillie Kittredge. The primary maintainers are now Ethan Sommer and Matthew Strait.

Thanks also to:

Support This Project

We have spent thousands of hours working on l7-filter, which is free for anyone to use. If you have found it useful, please consider slipping us $10 or any amount you feel is appropriate.

Computer code associated with l7-filter (including, but not limited to, programs, patches, the protocol definitions and the website code) is licensed under the GNU GPLv2.

Creative Commons License
Content associated with l7-filter that is not computer code (including, but not limited to, the human readable content of this website, the offline documentation and the logo) is licensed under Creative Commons Attribution-ShareAlike 1.0. Logo Valid XHTML 1.0.

Last updated 7 Jan 2009