Add gaming option

GAMING.md

@@ -0,0 +1,36 @@
+## Gaming service
+
+### Configure pppoes
+/etc/api.conf 
+```
+apikey=SecretTokenRandom
+allowip=10.168.100.
+```
+allowip must be set to ip of your nat
+
+### Configure radius
+Configure for gaming service radius attribute "Login-LAT-Service" with value "gaming"
+
+### Configure nat
+* Run several instances of pppoe gaming pollers that will retrieve list of gaming users
+```
+gamingclient  -u http://pppoeip:apiport/ -k SecretTokenRandom 
+```
+apiport by default 9000, might be different in some cases
+
+* Configure ipset for gaming users
+```
+ipset create gamingclients hash:net timeout 120
+```
+Also add relevant rules to nat users to different pool, for example:
+```
+iptables -t nat -A POSTROUTING -m set --match-set gamingclients src -j SNAT --to-source $GAMING --persistent
+```
+where $GAMING is ip of your gaming pool (1.2.3.1-1.2.3.10 for example)
+
+### How it works?
+* User login and get gaming service attribute from radius
+* API daemon will detect such user and put in special list available over API HTTP GET request
+* Gaming poller will retrieve list of users and put them in ipset each X seconds
+* NAT will detect users in ipset and will put them in gaming pool
+* If user will be disconnected, gaming poller will not readd user, and it will be removed from ipset after 120 seconds by ipset timeout