Hey AngelofDeath! Good on you for going into battle with Linux.
One thing I should just point out is that the amount of help any of us can give you is entirely dependent on how much information you can give us.
Based on your previous error, it appears that the server was trying to bind to an IP/port that is already in use on your server. This could well be because you already had an instance of L2J running when you tried to run it again. Or it could just be an issue with the IP/port you configured it to use.
Another thing to point out: If you've configured the IP in your config.xml file to be "127.0.0.1", you're *not* going to be able to connect to it. This is because that IP configuration defines which IP range can connect to the server. 127.0.0.1 is "localhost", which means that ONLY your ubuntu server will be able to connect to it. For the sake of simplicity, you should probably set the IP to "0.0.0.0", which means that any host with any IP address will be able to connect to it. This is generally something you want for a game server.
So, let's see if we can get some insight into your server environment. Would you be so kind as to run the following commands on your server, and then paste the output here?
First, we need to know what processes are currently listening (on the network) on your server:
sudo netstat -npvat | grep -i listen
Next, we need to see exactly how you've configured your config.xml file:
Note that there are two scripts you need to start in order to access your server:
startLoginServer.sh and startGameServer.sh - make sure you start them both, in the order listed.
I'd also like to see what has failed in your previous attempted runs, so if you could paste the output of stdout.log here, that would be awesome.
Finally, let's start the server. We're going to put Bash (linux commandline shell) into debug mode, so we can see exactly what the scripts are trying to do, and hopefully figure out where they're failing:
bash -x startLoginServer.sh
bash -x startGameServer.sh
Please post the output of the above here as well - it may be lengthy, so you probably want to use a service like pastebin.com, so you can link your outputs to us in a forum comment.