Hi Jack,
I try to give some examples. Before we can start, you have to set a port that dosbox can use. Consult your modem/router manual for this if you don't know how ^^.
Let's say we want to play DOOM2 over a modem connection. You want to set up your dosbox to act as the "server". So first of all, you need to set the port(for an internet session very important!). To do this, you should edit your config like this:
serial1=modem listenport:12345
or by typing in this on the dosboxshell:
config -set serial serial1=modem listenport:12345
(I think you can type something shorter in dosbox but I'm not sure)
And that's it. Next I will have to know your internet IP. To look what this IP is, go to sites like this one: http://www.wieistmeineip.de . After you told me that address(let's say it is 213.64.32.192) we can run a modem based session by running sersetup.exe from the DOOM2 directory. You (as the server) need to typing the "-answer" parameter. So let's say we want to play on skill 4 with respawn, then your commandline would look like this:
sersetup.exe -com1 -irq 4 -16550 -57600 -answer -skill 4 -respawn
(COM1/COM3 has IRQ4 and COM2/COM4 has IRQ3!!; 16550 is the UART and 57600 is the BAUD.)
And my commandline would show up this:
sersetup.exe -com1 -irq 4 -16550 -57600 -dial 213.64.32.192:12345 -skill 4 -respawn
The one who's dialing has to add the portnumber the server uses to servers' IP with a ":" between.
If you want to use the nullmodem connectivity, one site acts like the server and the other as the client. So you are the server and I'm the client.
In your config you have to set one [serial] like that:
serial2=nullmodem port:12345
And the same line in my configfile would look like this:
serial2=nullmodem server:213.64.32.192 port:5000
This method will connect our dosboxes. Now we will use "dm.exe" from the DOOM2 directory to connect... so we started dm and after we done the gamesettings, we just say "already connected" in the modem/nullmodem part.
That's it. I hope this will help you. If not, send me a mail at Punker_1992@live.de and I will write you a little textfile 😉