ＦＯＮの公式ＨＰのダウンロードコーナーには下記の記述がある。
LinksysやBuffaloでＦＯＮルーター化を試してみてはどうか。

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All FON firmwares are based on OpenWRT, an open-source Linux distribution
for embedded devices.

　OTHER FON SOCIAL ROUTERS

But if you have some technical skills, and you own a compatible router, you can also download the FON firmware
and install it into your router yourself. The FON firmware has different versions depending on the Linksys or
Buffalo router that you use. Here you can download the FON firmware for Linksys WRT54G (pre-v5), WRT54GL,
WRT54GS and WRT54GSv4, or for Buffalo WZR-RS-G54, WHR-HP-54, and WHR-G54S.

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