We ran into a problem with Hudson as detailed here, this is happening in a virtualized environment as the one described above (linux-vserver)
We tested hudson+vserver (this might happen in other virtualized environment as well) and found out that it's not listening in all interfaces (perhaps due to the vserver restrictions), but also, after some debugging we found out that maven-agent has a hardcoded socket connection to use only the loopback interface as it's shown here.
Shouldn't it be fixed so it add some means of fallback mechanism that makes hudson first try the loopback interface, then try with the ethernet ones?
Indeed the virtualization layer should offer a fully functional and non-restrictive environment to the upper laying processes, but unfortunately this is not the case.
Same bug was present with maven3 under the same conditions.