Minecraft – Is infinite inventory possible in multiplayer creative mode

Well, I found the answer but I can't take credit for it. I emailed the creator of MineOS Crux directly, William Dizon, and he got back to me in the same day! Very impressed.

Turns out that the default installation of MineOS Crux sets up the Linux firewall (iptables) to only accept incoming Minecraft connections on the default port, 25565. That means even though my second server was merrily running away, any attempts at connecting were blocked. Mr. Dizon passed on this link from the MineOS Crux wiki that explains how to add additional ports to the iptables:

https://minecraft.codeemo.com/mineoswiki/index.php?title=Iptables

Once I followed the steps, set up my additional port for the second server, everything worked! I had forgotten about iptables, and that is a little embarrassing, but live and learn... again ;)

Thanks again to Will Dizon!

Solved it!

A meandering discussion on the Talk page for the server.properties article on the Minecraft Wiki indicates that this is Forge's fault. Apparently it redefines spawn-protection to be a boolean that turns protection on or off entirely (which you can't do in vanilla), and defines a new variable, spawn-protection-size for what the former variable means for a vanilla server.

As a side effect, it appears that a server with the Forge API installed will honour the default spawn-protection area of 16 blocks until you edit the variable, at which point it treats it as boolean and looks for spawn-protection-size instead, doesn't find it, and effectively turns spawn protection off entirely.

So this is what happened to me then. Adding spawn-protection-size=42 to my server.properties file made spawn protection work (again) as expected. Redefining configuration variables is poor practice!