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====== schachtmeister2 ======

''schachtmeister2'' is a daemon for white- and blacklisting specified ISPs, hosting providers and so on. It was created for the Der Bunker Tremulous server to combat malicious players evading bans.

The source code is available [[https://redman.xyz/git/schachtmeister2|here]].

The daemon works by looking up a given IP address in WHOIS databases and reverse DNS records and analyzing the results. Its configuration file, ''schachts.list'', is a list of keywords to be searched for along with a **partial rating**. The program's output, the **rating**, is the sum of partial ratings of all matched keywords.

===== Usage =====

Since the daemon is meant to be used with a Tremulous server, it communicates over UDP. The protocol is extremely simple. To query ''schachtmeister2'' send an UDP packet (port 1337) that looks like:

''\xff\xff\xff\xffsm2query ADDRESS''

Note the four leading ''0xFF'' bytes. The daemon will send a reply to the sender's address and port that will look like:

''\xff\xff\xff\xffsm2reply ADDRESS RATING''

Here's an example using BSD's netcat, asking for the rating of ''8.8.8.8'' (Google's DNS):

  $ printf "\xff\xff\xff\xffsm2query 8.8.8.8 | nc -u 127.0.0.1 1337
  ����sm2reply 8.8.8.8 0

===== The list =====

The daemon needs a list of keywords to operate meaningfully. The program looks for a file named ''schachts.list'' in its working directory. Below is an example list:

  // a few known VPS and VPN providers
  revdns	-50	tcpvpn.com
  revdns	-50	vultr.com
  
  whois	-50	"OVH"
  whois	-50	"DigitalOcean"
  whois	-50	"Digital Ocean"
  
  // Desala's ISP
  revdns	-10	.dynamic.chello.pl

The columns are:
  - Where to look for the substring: ''revdns'' or ''whois''?
  - The partial rating or how much the total rating changes if this substring is found.
  - The substring to look for. Use quotation marks if you need spaces. The program does not support regular expressions yet.

Whitespace doesn't matter but I recommend tabs for proper alignment. You can use C++-style one-line comments.

===== Reloading on the fly =====

Restarting the daemon clears its cache, so you might want to avoid it. To make ''schachtmeister2'' reload the list, send ''SIGUSR1'' to the process.

===== Limitations =====

This is one of those programs that I've written quickly, as crude prototypes, but have worked exceedingly well.  As I couldn't be bothered to rewrite the program better, it's not very flexible and works well only in a single application. I might continue working on it if there's demand outside of Tremulous.