Last week (2010-01-19 or so), I stumbled into an IPv4/6 problem with Java. It turns out, this is due to a known issue from 2005: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6342561
If any of you Unix/Linux users are getting IPv4/6 related
network problems (you'll notice this because Java programs,
e.g. Maven, all of a sudden get "Connection failed" messages
when downloading artifactcs), make sure
/etc/sysctl.d/bindv6only.conf
has:
net.ipv6.bindv6only = 0
and reboot, or to just try it out (non persistent):
# echo 0 > /proc/sys/net/ipv6/bindv6only
or add: java.net.preferIPv4Stack=true
to your JVM options.
Debian users pulling from the testing or unstable pool have experienced this problem for a week now, if derivatives such as Ubuntu haven't yet, you're probably up for it in the next release(s) ;-)