It is possible for French citizens living abroad to vote by the internet in this weekend's legislative elections (Elections législatives). The process begins at this website. Among the supported operating systems are Ubuntu Linux as indicated here. When I go to vote it tells me Java is not working, (Java : non installé ou la version détectée n'est pas à jour. Votre configuration ne satisfait pas les conditions requises pour pouvoir voter en toute sécurité par internet) even though my Java is up to date.
The second link covers most of the details needed to solve this problem, but not all. It tells you that Firefox 9,10 or 11 are supported but doesn't tell you how to do it with Firefox 13. It tells you that the Openjdk version of Java is not supported, while Oracle Java is, but it doesn't tell you how to 'activate' Oracle Java if you have both versions installed.
The website makes use of the Java browser plugin, but the version it uses is not supported any more by Ubuntu. So you have to download it from Oracle's website. If you use a version that's too old (< 1.6.0_31) Firefox 13 will not allow you to use it, because of its strong security standards. If you use a version that's too new (> 1.7) you will have certificate problems. Version 1.6.0_32 is recommended and you can download it here.
Once you have it, run these commands:
The last command is necessary if you have Openjdk6 already installed.
Restart your browser, cast your vote and after you can remove Java 1.6 with;
if you need it.
You have until Tuesday midday to cast your vote.