After playing around a little bit too much with my OMV box I decided to nuke and pave.
Before reinstalling I had taken notes of all important configurations including the firewall configurations. However, for some reason (most likely because the instructions was available here Example of OMV's firewall) I had not taken any notes of the first 3 firewall rules, the ones found in the linked forum post. Now, unfortunately it seems like the pictures from the linked post have been deleted from ImageShack.
So I did some thinking and digging on my own, and I think I have got the first two correct:
1. Family: IPv4, Direction: INPUT, Action: ACCEPT, Protocol: All, Extra options: -m conntrack --ctstate ESTABLISHED,RELATED
2. Family: IPv4, Direction: INPUT, Action: ACCEPT, Protocol: All, Extra options: -i lo
However I am not sure about the third rule, which allows clients to ping the OMV box. If I remeber I had it like this:
2. Family: IPv4, Direction: INPUT, Action: ACCEPT, Source: 192.168.0/24, Destination: 192.168.0.163, Protocol: ICMP
(i.e. no Extra options). However, when looking at posts and guides on other forums everybody seem to give also some parameters?
Any one care to comment (Did I get any of them right)?