alert ftp $EXTERNAL_NET any -> $HOME_NET any (msg:"GPL FTP invalid MODE"; flow:to_server,established; content:"MODE"; nocase; pcre:"/^MODE\s+[^ABSC]{1}/msi"; classtype:protocol-command-decode; sid:2101623; rev:7; metadata:created_at 2010_09_23, signature_severity Unknown, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26;)