Disable access to open Minecraft servers without disabling internet?

January 11, 2018 9:39 PM

I want to disable access to open Minecraft servers from the computers my kids use to play. They should still be able to play with each other on LAN as well as on pre-approved Realms (one of which we're paying for), but not join open server free-for-all's. Is there a way to do this? PC/Mac edition.
posted by rouftop to Computers & Internet (6 answers total)

The default port is 25565, so you could firewall that at the router with exceptions for the LAN range and pre-approved external domains/IPs. That doesn't help if a server's running on a non-standard port.
posted by holgate at 9:49 PM on January 11, 2018 [4 favorites]

I think Windows has a firewall with settings that can be configured per-program. At least theoretically it would be possible to sit down and work it out so that Java's executable is only allowed to connect to specific other places. (I was going to poke at it a bit more but you seem like a techie person so you're probably in as good a state to work that out from this point as I am.) This gets around the problem of trying to just pick a specific port; I think there's a pretty good chance you could at least figure out how to whitelist only the appropriate places. Going off what holgate said, I looked and there are definitely nonstandard-port servers listed on some of the big sites that list public Minecraft servers.

Minecraft itself doesn't contain anything to do this kind of blocking in Vanilla. I did some searching on the usual place I look for mods--there are none I can find that change this functionality and I strongly suspect that this isn't a part of the program that Forge really exposes for modders. But even if that client mod did exist, client mods aren't that hard to disable for the user. If the OS firewall trick doesn't work, though, and you don't get more responses from here, I'd check on Reddit, because Reddit's /r/minecraft and /r/feedthebeast (the latter for mods) are pretty active and basically the only reason I have a Reddit account.
posted by Sequence at 12:25 AM on January 12, 2018 [2 favorites]

If you have a list of the sites add them to the "host" file with an ip address 127.0.0.1

That redirects the access to the local test address.
posted by sammyo at 4:26 AM on January 12, 2018

When my kids were young I used openDNS as my DNS provider. I set the content filtering high and then exempted the site they were allowed to get access. For my wife's and my computer I entered static google DNS addresses to allow open access.
posted by tman99 at 7:32 AM on January 12, 2018

Oddly, I don't know if there's reasonable a way to do this, especially since you're trying to block a Mac and a PC and presumably don't want to set up fiddly firewall rules on both machines. (Firewall rules are always fiddly.) If there was a certain problematic server, as noted, you could blacklist it in /etc/hosts (Mac and Windows have one with slightly different naming conventions). And you could block all Minecraft access to the standard port. But I think you might need to do some quality firewall rule writing, not to mention find which IP ranges are being used by the Realms you're paying for.
posted by wnissen at 3:58 PM on January 12, 2018

OpenDNS blocking presumably won't help you if the kid is using IP addresses to connect to Minecraft servers, so that's a consideration as well.
posted by Aleyn at 8:12 PM on January 12, 2018