alert tls $EXTERNAL_NET any -> $HOME_NET any (msg:"ET INFO Applied Privacy DNS over HTTPS Certificate Inbound"; flow:established,to_client; tls.cert_subject; content:"CN=doh.applied-privacy.net"; bsize:26; fast_pattern; tls.cert_issuer; content:"C=US, O=Let's Encrypt, CN=R3"; bsize:28; classtype:misc-activity; sid:2035125; rev:1; metadata:attack_target Client_Endpoint, created_at 2022_02_08, deployment Perimeter, performance_impact Low, confidence High, signature_severity Informational, tag DoH, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2022_02_08;)