Check to see if SmartFoxServer is running. Note that I have never used SmartFox, so I don't know the exact name that you'll be looking for, but I'm assuming that it will have "smartfox" or "sfs" somewhere in it:
ps -ef | egrep -i "[s]martfox|[s]fs"
If it is running, that command should output some information on the process. (The square brackets in the regular expression make sure that this command does not find itself in the process listing).
Now, check to see if it's attached to a port:
lsof -i :9339
If SmartFox is running, you should get some output that ends with ":9339 (LISTEN)"
So, now we've checked if the process is running or listening. The last thing to check is if there is a firewall that is blocking it from being accessed. Check to see if your firewall is enabled, and if so, what its settings are. I'm assuming that you would be using the default firewall for Ubuntu, ufw
:
sudo ufw status
If the firewall is enabled, you should see some settings; otherwise, it should tell you that the firewall is not loaded.
If it is enabled, you can try allowing the port in question:
sudo ufw allow 9339
edit: oops, I hadn't noticed that you said that UFW is off. Sorry for assuming you hadn't checked that yet.