I had the same problem ssh and x-forwarding after disabling ipv6 in sysctl.
It seems that disabling ipv6 using sysctl breaks both ssh x-forwarding and java networking, at least in my case.
To disable ipv6 I created this file: / cat /etc/sysctl.d/disableipv6.conf /#Equal to sysctl -w net.ipv6.conf.all.disable_ipv6=1 net.ipv6.conf.all.disable_ipv6=1 As explained in the comments here: http://www.debian-administration.org/article/Disabling_IPv6_under_a_2.6_kernel Re-enabling ipv6 made both ssh x-forwarding and java networking work. For reference, for Java to work you need to change the value of /net.ipv6.bindv6only /in sysctl to 0 as explained here: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=560044 Regards, Walter