I've upgraded from 1.5 to 2.0 by adding the new repo and performing a yum update.
After the upgrade I had to cleanup the plugins folder, then installed head plugin again and elasticsearch started just fine.
Local queries seem to work fine and so does Kibana.
The problem is when I try to connect via browser to the head plugin (or any other direct query) I get a connection refused.
The elasticsearch.yml seems ok, as it states that by default it will listen on the interface 0.0.0.0, which is what I want.
Any ideas on what could be happening here? And what can I do to get it to listen in all interfaces again or discard that as the problem?