This step is actually optional. If you are on a LAN and if you can punch proper holes need by DOSBox in your firewall, you can easily get around the issue. However, Hamachi makes things possible if you don't actually have access to your router or whatever you need to do a port forward. Note, you may still have to punch holes in your firewall if you have a 3rd party firewall like Norton, McAfee, ZoneAlarm or Comodo, but the default Windows XP firewall should pose no real issues.
The down side is that your opponent also needs to be on Hamachi. You can't pass out your Hamachi internal IP address and expect some one outside the Hamachi network to connect with you.
Hamachi is available for Linux, OSX and Windows 2K,XP,2K3 & Vista. Unfortunately, there is NOT a version available for Windows 9x, ME or NT. I've not had a chance to test this out on Linux or OSX, so fore the time being this tutorial is Windows only.
If Hamachi does not work for you, you may try your luck with another VPN solution like OpenVPN.
Get and install Hamachi: http://www.hamachi.cc/download/list.php
Run the setup program, it's pretty much a "click-through" process. You can check the "Block vulnerable Microsoft Windows services" if you wish, it did not prevent DOSBox from connecting though it's IPX tunnel, nor do you need to sign up for the premium service.
When you launch Hamachi for the first time, it should present you with a quick guide to the program. I'd recommend going through it if you're not familiar with Hamachi, it's only a few short windows with explications about how things work.
Once your connected to Hamachi and everything is resolved you should have been issued an IP listed at the top of the main Hamachi window.
Hopefully you've gotten this far, if you are having troubles here, you are probably having issues with your firewall. You'll probably want to checkout the Hamachi help pages at this point.
Now to connect to a network group.
Setting up a network
Click the network icon at the bottom of the window.
A popup menu should appear with choices allowing you to either Create a new network
or Join an existing network
If you are setting up a network, click Create a new network
and fill out the information in the Create a network
Then just share the network name with whoever you want to play with.
If you are going to connect to an already established group like TchernoDOS click Join an existing network
and fill out the group information in the form:
Once you are connected, players who are online should appear highlighted with a green star.
Because DOSBox's IPX tunnel is a little ping sensitive, you might have to try to the IPX network a number of times if your ping is much over 200ms. To check the ping of your opponent, double-click on their name, or right-click and select Ping
from the menu. This should invoke the command line "ping" utility.
I've connected to a game with a ping as high as 300ms, however things start to get laggy at much over 200ms
If you receive the "Request timed out." multiple times you may have trouble connecting through the DOSBox IPX tunnel at all.
Now that you have Hamachi up and running it's time to start DOSBox.