the eth0 device is the one your probably looking for as far as IP goes.
BUT, your going to need to look up a lot of things, and it depends on what your doing with the system. This place is great, but I learned a long time ago it is not a place for people looking for an easy run. You have to be willing to learn. The list depends on what you want to do, a small server just for you and friends on a lan is shorter as long as you stick to lan or vpn to play.
If you use it for lan and never set anything in your router you can probably just set the local ip, If I remember correctly the "game server" settings.ini and the tables in the database are all set to 192.168.0.15 and the bins are hexed to 192.168.0.0 <-this is a local network range from 192.168.0.0 to 192.168.255.255. if you do not know what that means, you will really have a long way to go. But it needs to be changed with the patcher in the second link to whatever ip you decide to use.
You probably want to set your server systems ip to something else.
***lookup "setting a static IP in centos 7".***
and set eth0 to use the address set for the "server software"
If your even thinking of setting up a "private server" without someone on your team who knows Linux administration and networking your not going to get very far so you'll have to learn it or find someone who knows to join your team. Your also going to need to know sql and depending on what you use sql specific to that software. Postgresql is used a lot because it's free but not everything there lines up with every other version. MySql is rather standard but since the db is already in pg you would at least need to setup the first to export the db and try to import it to the new.
Even more to learn so I will ask just to make it easier. Are you doing this for you and some friends, or looking to setup a cash grab server. The first you can kind of hammer it together and let it run, the second your going to need a lot of lessons in a lot of subjects.
Edit: also if your thinking of a "private server" and not a server for you and friends. I will suggest you re-think this and rethink it hard. But putting money into a server before you know how to use it was not the normal way to go in the "just a few friends" situation, This server does not really need that much power to run, UNLESS your planning on handleing a large crowd.
Don't take this the wrong way, I am not being mean here, but I am trying to save you a lot of pain. "Private servers" are on their own a bit of a shady business, even under each other. There is a good chance that you and anyone connected to your server will suffer attacks.
If you need help to get this running your probably not going to be able to work out the security you need, and "assuming" you find a way to get your hands on some of the source code to do it, your probably not going to be able to fix the bugs that are still in it, your not going to be able to offer any updates, and nobody is going to be happy with any of that.
if you charge anything the "wrong way" your going to get into so much trouble you'll be lucky to come away with your underwear and socks, because the lawyers are going to take everything else.
If you think you could make money, your not. Most of the people running private servers also have a real job and just do it because they enjoy all the crazy challenges that come with it, and probably passed on any kind of auto-installs.
On the other hand if it is just a "for a few friends" server, just keep it between you and keep looking in these forums, but be ready to accept that not everything works like in the retail servers.