I'm trying to make a server on my computer. The problem is that I'm the only that can go in, with localhost. My friend can't. I opened ports and I think everything is done, but it don't works. Also, I saw that in settings.ini there is no server-ip like in bukkit.
What I did wrong?
MCServer listens for connections on all available interfaces, so there's no need to specify an IP address.
Just to be sure, your friend isn't using "localhost" as the server address, right? That won't work, because his "localhost" is his machine, which doesn't have the server running; he needs to type in your computer's IP address or hostname (if available).
If you're on Windows, open command prompt and type "netstat -na" to verify that your server is indeed listening on the ports. You can also use "ipconfig /all" to find out your IP address.
If your friend is not in the same network as you are, you will need to configure your router's NAT to forward MCServer's port to your computer. I can't help you with that, because that's very specific to the model of the router.
I know, my friend is using the host I registered in No-Ip. Also, with my external Ip adress it don't work. Do hamachi work with MCServer?
I don't see a reason why it shouldn't. Note though that I have no idea how hamachi works, but from the general description it seems that it doesn't need any support in the server.
Now it works. It was because I was going in with my external ip and it said can't reach server. Now I go in with localhost and my friend with my external ip and it works.
About this: would it be possible to specify the ip to listen to - for multi-ip multi-server machines?
It definitely is possible, but is it really needed that much? It doesn't feel like a top priority to me.
It's not 'top priority' as such, but it is a pretty essential feature if we wanted more than one server on a machine.
Not really - just bind to different ports, rather than different interfaces.
Having a server on the default port is very nice (even with SRV records), so I think it's still quite an important feature.