alert ftp $EXTERNAL_NET any -> $HOME_NET any (msg:"GPL FTP FTP anonymous login attempt"; flow:to_server,established; content:"USER "; depth:5; nocase; content:"anon"; distance:0; classtype:misc-activity; sid:2100553; rev:8; metadata:created_at 2010_09_23, signature_severity Unknown, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26;)