This is an example to show people how to use OMV's firewall. I have not included all services or limited sources as much as I could have. I am simply putting this out to give people an example of a firewall that will work and keep enough opened so the main functions of OMV are not hampered (updates, upgrades, etc..). I will probably update this later but many should find this helpful.
At first you should setup these 3 rules....
Link to picutres of thread where firewall rules are:
Help setting up firewall (iptables)
The next 2 rules you should add would be port 22 for ssh and port 443 ( or port 80, depends on if you are using http or https) for access to OMV's web-gui.
Here is an example of some rules...
The last rule you want to enter is your drop or reject everything else rule. Once you do this ports not in the rules will be blocked so it is important that port 22 is open at the minimum. You can turn off iptables via port 22 if you made some error. I use REJECT instead of DROP as my OMV is already behind a firewall and I want a minimum response if I ping my OMV. Ser Erris and I discussed this in a way older post. Hopefully this will help many of you to be able to use the web-gui firewall in OMV. This just adds a litte more security if you are opening up ports to OMV. I think it is best to eventually get a vpn service working. I only have a port for vpn and plex open, so 2 ports, on my server but can access everything via the vpn.
PS- There may be some rules that you do not need all the time. Say you want port 21 open just temporarily for FTP. When you want to use FTP have the rule be ACCEPT. When you don't want to use a specific rule edit it and the ACCEPT to REJECT, then save and apply. That will close down the port when you are not using it.