alert tcp $HOME_NET 5060 -> $EXTERNAL_NET any (msg:"ET VOIP Multiple Unauthorized SIP Responses TCP"; flow:established,to_client; content:"SIP/2.0 401 Unauthorized"; depth:24; threshold:type both, track by_src, count 5, seconds 360; classtype:attempted-dos; sid:2003194; rev:7; metadata:created_at 2010_07_30, confidence Medium, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_03_06;)