Networking giant Cisco Systems has been sued by the Free Software Foundation, a report reveals. Filing with the help of the Software Freedom Law Center, the FSF has accused Cisco of violating the General Public License under which the Linux operating system is distributed. Companies that want to use Linux can typically do so for free; the GPL stipulates, however, that any changes made for a Linux variant must be shared with the public.

The problem can be more directly traced to the Cisco-owned Linksys, which makes a number of products, such as routers, that rely on Linux. The FSF notes that it first attempted to warn Cisco about Linux issues in 2003, at which point the latter admitted mistakes and said it would try to solve them. Despite regular talks, however, the FSF alleges that Cisco has kept violating the GPL, leaving no choice but to file suit.

Should Cisco not settle out of court, the FSF is seeking injunctive relief and an injunctive ban on Cisco's Linux-based products, as well as damages, legal costs and any illicit profit Cisco has obtained. Cisco defends itself as a supporter of open-source software, and in fact claims to be "substantially in compliance" with the terms of the GPL.