alert tcp $EXTERNAL_NET any -> $HOME_NET 21 (msg:"ET POLICY FTP Frequent Admin Login Attempts"; flow:to_server,established; content:"USER Admin|0d0a|"; nocase; threshold:type threshold, track by_src, count 3, seconds 30; classtype:attempted-admin; sid:2009668; rev:2; metadata:created_at 2010_07_30, confidence High, signature_severity Informational, updated_at 2019_07_26;)