I'm also adding to anyone interested that I have a home server running Debian 8 (only one ethernet interface though), in case that makes things more simple or gives us more alternatives on how to set things up.

Uhm, why so complicated ? If it's only about playing a two player game, just use an old ISA modem and connect it to your router's telephone plug. 😀
Then just dial your friends phone number and play the game. Modern routers do sometimes have got a FAX compatibility mode for Voice-over-IP (VOIP),
which can help to improve sound quality. I know, it's not ideal for this purpose, but 2400 to 9600 (or 14400) baud should work fine.
I don't know about latency (ping times), though. I think that's an issue you will also encounter when sending IPX over IP or UDP protocols..
https://en.wikipedia.org/wiki/Voice_over_IP#Fax_support

"router's telephone plug"? Extraordinarily few routers have phone lines built in to them. Yeah, if you have a service that provides home phone service over the internet connection (like through a cable company) it will, but you have to be paying for it.

The big problem with old games is that the earliest "network" DOS games often didn't use TCP/IP, they used IPX. Which isn't internet-routable at all.

For merely playing "vintage games over the internet" especially for Doom, you can use the modern ZDoom engine, which has full-internet TCP/IP multiplayer support built in.

Jo22 wrote:

Uhm, why so complicated ? If it's only about playing a two player game, just use an old ISA modem and connect it to your router' […]
Show full quote

Uhm, why so complicated ? If it's only about playing a two player game, just use an old ISA modem and connect it to your router's telephone plug. 😀
Then just dial your friends phone number and play the game. Modern routers do sometimes have got a FAX compatibility mode for Voice-over-IP (VOIP),
which can help to improve sound quality. I know, it's not ideal for this purpose, but 2400 to 9600 (or 14400) baud should work fine.
I don't know about latency (ping times), though. I think that's an issue you will also encounter when sending IPX over IP or UDP protocols..
https://en.wikipedia.org/wiki/Voice_over_IP#Fax_support

Sorry to say I don't have landline any more. Neither does my cousin (who is actually connected to the internet over LTE/4G). We both have a regular LAN at home and just need to be able to somehow establish a bridge between the two to play LAN games. Ping/latency shouldn't be an issue as I'm sitting on nearly 200 Mbit of bandwidth and he has (even in the worst case scenario) at least 30 Mbit. Should be ample enough for old games.

Anonymous Freak wrote:

The big problem with old games is that the earliest "network" DOS games often didn't use TCP/IP, they used IPX. Which isn't internet-routable at all.
For merely playing "vintage games over the internet" especially for Doom, you can use the modern ZDoom engine, which has full-internet TCP/IP multiplayer support built in.

If there is no way to fool IPX to work across the internet, then I guess we're going to be limited to just TCP/IP and Windows 95 or later-era games... 🙁

On a side note, here's the foundation for the rig: a Compaq DeskPro EP from the late 90's. I haven't opened it up yet, but looks to be a Celeron 466 MHz with built-in video and audio. With a few tweaks and select parts it should be great for retro gaming.
So far the best part is the heavy duty HP keyboard from the 80's, which should be able to handle multiple keypresses well (required for hot-seat multiplayer).

No one has heard of Kali? http://www.kali.net/

I don't know if it still works, but I remember playing Descent on Kali a long time ago.

Get notebooks and play whenever he is in town.

For my LAN friends (playing since the 1990s) I brought 5 T61s to the EU. Windows XP fully supports IPX/SPX so we play AOE2FE / RA2 that way. The T61s + PSUs + mice hardly take up room on a big table and in storage. Perfect solution.

Hmm... found at least one reference that states IPX can work over VPN:

Bridging in OpenVPN OpenVPN allows two different modes of operation: routed mode and bridged mode. This article is about the lat […]
Show full quote

Bridging in OpenVPN
OpenVPN allows two different modes of operation: routed mode and bridged mode. This article is about the latter.

Do you need bridging?
This question comes up regularly when somebody asks for advice in configuring a bridged VPN. Bridged mode has a higher traffic overhead, since it works at layer 2 and as such broadcasts are sent into the VPN, and also, as already mentioned, data packets can be up to 1514 bytes. Normally bridged mode is needed only in two cases:

• You really need to create a layer 2 domain. This may be because you need to use protocols that rely on broadcasts or multicasts (eg netBIOS, LAN games)
• You need to transport non-IP traffic (eg IPX, AppleTalk?)

https://community.openvpn.net/openvpn/wiki/OpenVPNBridging

FuzzyLogic wrote:

No one has heard of Kali? http://www.kali.net/
I don't know if it still works, but I remember playing Descent on Kali a long time ago.

Kali looks the perfect solution to my needs! I only hope that it still works. Will definitely give this a go before I go mucking about with VPN.

As of 2014, the software has for the most part died. However, there is still a small, loyal following (largely residing in the Descent Channel) that uses the software as a chat room. Games, such as Descent, are still played among this group of gamers.
https://en.wikipedia.org/wiki/Kali_(software)

Anonymous Freak wrote:

"router's telephone plug"? Extraordinarily few routers have phone lines built in to them. Yeah, if you have a service that provides home phone service over the internet connection (like through a cable company) it will, but you have to be paying for it.

Um, I don't know how it is in the US, but in my place the analogue telephone line (landline) is getting replaced by a digital connection (internet)
and most DSL or cable routers (or modems) do normally have a connector for a classic analogue telephone (like RJ11).
And doing a local call doesn't cost very much, I think. But again, I don't know how it is in the US (and how "local" is defined there).

(Edited.)

The one I was trying to remember - Hamachi
http://www.howtogeek.com/172762/how-to-play-o … r-the-internet/
Hamachi free has now been cut from 16 to a maximum of 5 users

Some others...
http://www.ghacks.net/2010/07/05/top-3-virtua … an-gaming-apps/

leonardo wrote:

Hmm... found at least one reference that states IPX can work over VPN:

Bridging in OpenVPN OpenVPN allows two different modes of operation: routed mode and bridged mode. This article is about the lat […]
Show full quote

Bridging in OpenVPN
OpenVPN allows two different modes of operation: routed mode and bridged mode. This article is about the latter.

Do you need bridging?
This question comes up regularly when somebody asks for advice in configuring a bridged VPN. Bridged mode has a higher traffic overhead, since it works at layer 2 and as such broadcasts are sent into the VPN, and also, as already mentioned, data packets can be up to 1514 bytes. Normally bridged mode is needed only in two cases:

• You really need to create a layer 2 domain. This may be because you need to use protocols that rely on broadcasts or multicasts (eg netBIOS, LAN games)
• You need to transport non-IP traffic (eg IPX, AppleTalk?)

https://community.openvpn.net/openvpn/wiki/OpenVPNBridging

I was just about to recommend a vpn

if you have fast pcs you can use dosbox to play ipx Dos-games over internet.

Maybe it works with 2 pcs with OpenVPN in bridged mode as a gateway.

Matth79 wrote:

The one I was trying to remember - Hamachi http://www.howtogeek.com/172762/how-to-play-o … r-the-internet/ Hamachi free has now […]
Show full quote

The one I was trying to remember - Hamachi
http://www.howtogeek.com/172762/how-to-play-o … r-the-internet/
Hamachi free has now been cut from 16 to a maximum of 5 users

Some others...
http://www.ghacks.net/2010/07/05/top-3-virtua … an-gaming-apps/

Sammy wrote:

if you have fast pcs you can use dosbox to play ipx Dos-games over internet.

Maybe it works with 2 pcs with OpenVPN in bridged mode as a gateway.

Thank you all for the tips.

It looks like right now the choice is between ready solutions such as Kali, Hamachi, Tunngle, Garena - and building my own VPN network by using a Linux server or dedicated router.
Of all the ones suggested, Kali and Hamachi seem most plausible (now that Hamachi was brought up, I do remember some friends using it earlier with Windows 98 and StarCraft). The biggest hurdle I guess, if there is one, could be that the so-called ready solutions may have dropped support for legacy operating systems and would thus not work any more.

Kali, which seemed like the most promising solution gave me a complaint about wininet.dll and after I placed one in the same folder with it keeps nagging me about a firewall test failing (even though I created a port-forwarding rule for both TCP/UDP to 2213).

I will keep you guys posted on what I find.

Put the '98 rig on DMZ setting on the router. That should avoid problems with Kali.

Kodai wrote:

Put the '98 rig on DMZ setting on the router. That should avoid problems with Kali.

That... that is asking for trouble. Unless I put a software firewall on it. Maybe even then.

I ran into a temporary setback when the monitor died on me. I just took it in today to see if it can be fixed cheaply. If not, I'll be on a hunt for a new tube...

The DeskPro is also giving me a hard time with the built-in hardware. It looks like the Intel integrated video isn't even properly backwards compatible with VGA or VESA, as I've run into issues testing quite a few older DOS games. Also, the built-in ADI SoundMax/AC97 audio is having trouble with it's SoundBlaster emulation. Heck, it can't even play sound properly on Windows. Looks like I'm going to have to invest into some replacement parts...

That is why I stick/stuck with TCP/IP based retro gaming like CivNet and such. Works great online.

leonardo wrote:

That... that is asking for trouble. Unless I put a software firewall on it. Maybe even then.

In the past several years, I've yet to see a DOS or 9x rig have any security issues being open on the net. Old worms, malware, and scripts just aren't out there any more, and the current stuff just doesn't target them. I wouldn't recommend advertising your IP, but I just can't see you getting targeted/attacked on a 9x rig. Stay away from browsing and just hook up for games. Disconnect when finished, and it shouldn't be a problem.