I’ve recently been playing a lot of Factorio with a friend. I’ve been hosting, but my desktop computer is behind far too many layers of NAT, and I can’t be bothered dealing with setting up port forwards. Up until today we made do with Steam’s networking support, which in our case ended up relaying the connection via one of their servers. This is amazing as a free, no-hassle service, but the performance was so-so. We’d get random lag spikes, or the initial map download would crawl along at about 1/100th of the speed we should be able to get. We’re both fans of Tailscale though, so maybe there’s an easy solution there?

Tailscale even have an article on sharing a Factorio server but it’s a ten minute long video1, and focused on setting up an actual dedicated server in Docker rather than just clicking the convenient “Host” button in the game client. What we did instead was:

1. I shared my desktop’s Tailscale node with my friend, by creating a sharing link in the Admin console
2. My friend accepted the link, and could then see my machine in their admin panel
3. I used tailscale lock to sign my friend’s desktop’s node key, as I have tailnet lock enabled
4. I added a grant to my tailnet’s ACL to permit access from my friend to the specific IP/port on my tailnet:

{
"src": ["friend@example.com"],
"dst": ["100.0.0.42", "fd7a::42"],
"ip":  ["udp:34197"],
}

After this, my friend could connect to Factorio by entering the Tailscale IP address, or the Tailscale hostname (as they use MagicDNS). Running tailscale status shows that Tailscale managed to establish a direct connection despite the many layers of NAT involved, and the performance improvements were significant and immediate.

We did a bit of testing, and confirmed that no other services on my machine are accessible. And sharing a machine by default only allows it to accept incoming connections, so I can’t get unwanted access to anything on my friend’s Tailnet, either.

I’ve written before about all the different ways I use Tailscale; this is yet another new way it’s solved a problem for me.

I’m not a fan of video tutorials at the best of times, but especially not when I want to do something as quickly as possible so I can get back to my addiction growing the factory. ↩︎