DNS: add event rules file

rules/dns.rules

@@ -0,0 +1,11 @@
+# Response (answer) we didn't see a Request for. Could be packet loss.
+alert dns any any -> any any (msg:"SURICATA DNS Unsollicited response"; flow:to_client; app-layer-event:dns.unsollicited_response; sid:2240001; rev:1;)
+# Malformed data in request. Malformed means length fields are wrong, etc.
+alert dns any any -> any any (msg:"SURICATA DNS malformed request data"; flow:to_client; app-layer-event:dns.malformed_data; sid:2240002; rev:1;)
+alert dns any any -> any any (msg:"SURICATA DNS malformed response data"; flow:to_server; app-layer-event:dns.malformed_data; sid:2240003; rev:1;)
+# Response flag set on to_server packet
+alert dns any any -> any any (msg:"SURICATA DNS Not a request"; flow:to_server; app-layer-event:dns.not_a_request; sid:2240004; rev:1;)
+# Response flag not set on to_client packet
+alert dns any any -> any any (msg:"SURICATA DNS Not a response"; flow:to_client; app-layer-event:dns.not_a_response; sid:2240005; rev:1;)
+# Z flag (reserved) not 0
+alert dns any any -> any any (msg:"SURICATA DNS Z flag set"; app-layer-event:dns.z_flag_set; sid:2240006; rev:1;)