In a Maven/Nexus environnement the settings.xml file is configured to use Maven mirror (see http://www.sonatype.com/books/nexus-book/reference/maven-sect-single-group.html) and because of this we don't need to configure proxy settings (for those who are behing a firewall..)

But it seems Forge don't use mirror information so that Forge project cannot be created/installed and lot of requests timed out...