alert tcp $EXTERNAL_NET any -> $HOME_NET 53 (msg:"GPL DNS named version attempt"; flow:to_server,established; content:"|07|version"; offset:12; nocase; content:"|04|bind|00|"; offset:12; nocase; reference:arachnids,278; reference:nessus,10028; classtype:attempted-recon; sid:2100257; rev:10; metadata:created_at 2010_09_23, signature_severity Informational, updated_at 2019_07_26;)