The Software Freedom Law Center (SFLC) said it has filed suit against two companies for allegedly violating the General Public License, which covers usage of Linux and thousands of other free and open-source products.
The suits are the second and third time that the nonprofit foundation has filed suit, signaling a willingness to use the court system to enforce the GPL.
The plaintiffs are two programmers--Erik Andersen and Rob Landley--who wrote BusyBox, software covered by the GPL version 2 often used in conjunction with the Linux operating system in embedded devices.
The suit was filed against Xterasys and High-Gain Antennas; both companies manufacture wireless communications hardware.
The SFLC said it had contacted the two companies to notify them about the alleged violations but were forced to file suit because they received no response.
In October, it settled a similar case with Monsoon Multimedia filed on behalf of the same plaintiffs over use of the BusyBox software.
Under the terms of the GPL version 2, people who make additions to software covered by the GPL have to make the source code of that program available.
"We let companies do what they like with BusyBox on their hardware, and what we asked in return was that they let us reproduce what they've done with BusyBox on our hardware. That's the deal embodied in the GPL," said Rob Landley, in a statement.