A group that promotes open source software filed a lawsuit against Cisco on Thursday, claiming that some of the networking vendor's routers violate the terms of open source licenses that govern the use of software embedded in the products.

In court papers filed in U.S. District Court in Manhattan, the Free Software Foundation claims Cisco's Linksys routers violate parts of the GNU General Public License, version 2, and the GNU Lesser General Public License.

Both licenses place restrictions on the ways in which open source software can be commercially used and distributed. FSF notes that Cisco uses GNU Compiler Collection and GNU Binutils, as well as other open source utilities over which the group holds copyrights, in its Linksys brand routers.

Cisco acquired Linksys in 2003 for $500 million.

FSF claims Cisco violated the licenses by failing to provide end users of its products with access to the source code for open source software embedded within the products, as required by the GPL and LGPL.

Cisco distributed to the public copies of the FSF's programs "in object code form via its Web site without providing complete and corresponding source code within the meaning of the licenses," FSF claims in court papers.

In the lawsuit, FSF claims Cisco brushed off its complaints about the matter. "Discussions have now proven unfruitful and the parties are at an impasse," the FSF states.

The group is asking the court to enjoin Cisco from further distributing Linksys firmware that contains FSF copyrighted code. It's also asking for all profits that Cisco received "from its unlawful acts."

Cisco has yet to file a formal response to the charges. Open source developers have prevailed in similar, past cases.