Querying Rust Servers

I was looking a at a thread where they used PHP code to query a server and get information. I managed to convert to c# and get it working, but there's not much information in there. How do APIs like this Battlemetrics example get so much more information like the description, map seed, etc? Do they use RCON? If so, how do they get past not using a password?

 

Found what I was looking for.

 

Could you share your findings? I'm trying to figure out the same thing.

 

This is what I found. I just grabbed the extra information and added it onto what I already had.