alert http $EXTERNAL_NET any -> $HTTP_SERVERS any (msg:"ET WEB_SERVER HTTPing Usage Inbound"; flow:established,to_server; http.user_agent; content:"HTTPing"; depth:7; reference:url,www.vanheusden.com/httping/; classtype:policy-violation; sid:2016845; rev:4; metadata:created_at 2013_05_14, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_04_24;)