Eclipse, JUnit and an odd networking issue

My coworker started having issues with getting JUnit to do anything in Eclipse. After some digging around, it was discovered that, for whatever reason, the JUnit runner was trying to create a network connection and couldn’t. He tried to perform an update of Eclipse plugins and that failed also, for the same network connectivity reasons.

After a lot of digging and much gnashing of teeth, he came across this page which outlines an issue where Java has started connecting using IPv6. We’re not sure if this is a Debian package issue or something from elsewhere but thankfully the LiveJournal page outlines a couple of fixes. The fix performed at the system level rather than by Java properties is what fixed things for him.

To check the system property, do this:

machine:/# sysctl net.ipv6.bindv6only

Which, if you’re having this problem should return 1. If you’re having this problem and get a return value of 1, issue this command next:

machine:/# sysctl net.ipv6.bindv6only=0
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