alert tcp $EXTERNAL_NET any -> $HOME_NET 21 (msg:"ET POLICY FTP Login Attempt (non-anonymous)"; flow:to_server,established; content:"USER"; content:!"PASS "; nocase; pcre:!"/^USER\s+(anonymous|ftp)/smi"; classtype:misc-activity; sid:2003303; rev:3; metadata:created_at 2010_07_30, confidence High, signature_severity Informational, updated_at 2019_07_26;)