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 😉

don't know what you want to do exactly but
if you want internet use hal's build that has network card emulated that works in win9x

Thanks both of you for the nicest responses.
I wonder if I just want to use dosbox to go online, such as using
Netscape 3.0 to view vogons. What are the general steps to achieve this?
Thanks once again
Jack

You'll need the dosbox MegaBuild. If you're using Windows as you'll need winpcap too.

I have managed to put everything in order.
with NE2000 setup okay.
But I can't seem to be able to use win3.1/netscape to go online
I downloaded the novell drivers,
then to type

lsl
ne2000
ipxodi
winpkt 0x60

But winsock said there wasn't any packet driver at 0x60
Beforehand, I tried to use another ne2000 file to connect.
It went fine except it couldn't find a DNS server. Thats the major concern here. Is twinsock/winsock able to be run under dosbox?
Thanks
Jack

you need to run windows from a booted image, AFAIR