alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET INFO Observed Google DNS over HTTPS Domain (dns .google in TLS SNI)"; flow:established,to_server; threshold:type both, track by_src, count 1, seconds 600; tls.sni; dotprefix; content:".dns.google"; endswith; reference:url,developers.google.com/speed/public-dns/docs/doh/; classtype:misc-activity; sid:2047866; rev:4; metadata:affected_product Any, attack_target Client_Endpoint, created_at 2022_02_07, deployment Perimeter, performance_impact Low, confidence High, signature_severity Informational, tag DoH, updated_at 2023_10_05, reviewed_at 2023_10_05, former_sid 2851058; target:src_ip;)