alert tcp $EXTERNAL_NET any -> $HOME_NET 5060 (msg:"ET VOIP INVITE Message Flood TCP"; flow:established,to_server; content:"INVITE"; depth:6; threshold:type both , track by_src, count 100, seconds 60; classtype:attempted-dos; sid:2003192; rev:4; metadata:created_at 2010_07_30, confidence Medium, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26;)