alert tcp $EXTERNAL_NET 5100 -> $HOME_NET any (msg:"GPL RETIRED Yahoo IM conference watch"; flow:from_server,established; content:"|0D 00 05 00|"; depth:4; classtype:policy-violation; sid:2102461; rev:6; metadata:created_at 2010_09_23, former_category CHAT, confidence Medium, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2026_08_28;)