alert tcp $EXTERNAL_NET any -> $HOME_NET 5900:5920 (msg:"ET SCAN Potential VNC Scan 5900-5920"; flow:established,to_server; flags:S,12; threshold:type both, track by_src, count 5, seconds 60; classtype:attempted-recon; sid:2002911; rev:8; metadata:created_at 2010_07_30, confidence Medium, signature_severity Informational, updated_at 2024_12_06;)