In September of 2022 I decided to try to identify the strings for all of the entries in Mojang's server blocklist. Through many different methods and approaches, including:
- data/current.txt contains the current blocklist, as fetched from https://sessionserver.mojang.com/blockedservers
- data/identified.txt contains all strings which I've identified since starting the project, in the format `hash=string`. It also includes ones that have been since removed from the blocklist.
- data/merged.txt contains the current blocklist but with identified strings merged in. This is the most useful file to use for contextual analysis.
For some reason, `update-todo` sometimes fails on certain systems, no clue why, but you can just manually run the `comm` command in package.json instead.
Don't prune identified strings that have been removed from identified.txt -- I'm keeping them in there for historical purposes. I might end up adding a separate file for removed strings at some point which would include verified former blocklist entries.
Beginning at Minecraft 1.9.3 r2, Mojang started blocking certain Minecraft servers using a blocklist.
From [wiki.vg's documentation](https://wiki.vg/Mojang_API#Blocked_Servers):
> _Clients check the lowercase name, using the ISO-8859-1 charset, against this list. They will also attempt to check subdomains, replacing each level with a `*`. Specifically, it splits based off of the `.` in the domain, goes through each section removing one at a time. For instance, for mc.example.com, it would try `mc.example.com`, `*.example.com`, and `*.com`. With IP addresses (verified by having 4 split sections, with each section being a valid integer between 0 and 255, inclusive) substitution starts from the end, so for `192.168.0.1`, it would try `192.168.0.1`, `192.168.0.*`, `192.168.*`, and `192.*`._
> _This check is done by the bootstrap class in netty. The default netty class is overridden by one in the `com.mojang:netty` dependency loaded by the launcher. This allows it to affect any version that used netty (1.7+)_
This includes wildcards, typos, '?' appended, mixed case, and other anomalies. Minecraft servers don't need to know their own hostname to function, so scanning the Internet for servers isn't very useful (except maybe with rDNS). Checking server lists is a decent way to find them though.
There used to be a way to bypass blocks via rotating SRV records, but this was patched in snapshot 21w13a (Mojira issue MC-136551, "Servers able to bypass EULA blacklist.")
There aren't many of these. Mojang does not block many IPs in the list. From some of our research, we found that they _used to_ but after one notable incident where they blocked ProxyPipe, they generally shifted direction towards blocking hostnames.
These are not valid DNS FQDNs, or even hostnames (some have spaces, underscores, etc). These often have "dns" and/or "test" in them, with various combinations of separators (including space), case, and appended digits.
