alert tcp any any -> any 502 (msg:"ET SCAN Modbus Scanning detected"; flow:established,to_server; content:"|00 00 00 00 00 02|"; depth:6; threshold:type both, track by_src, count 100, seconds 10; reference:url,code.google.com/p/modscan/; reference:url,www.rtaautomation.com/modbustcp/; classtype:bad-unknown; sid:2009286; rev:4; metadata:created_at 2010_07_30, confidence Medium, signature_severity Informational, updated_at 2020_11_12;)