[IMAPD] Brute force attack [5/1]

alert any $EXTERNAL_NET any -> $HOME_NET any (msg: "[IMAPD] Brute force attack [5/1]"; pcre: "/Login failed user=
| AUTHENTICATE LOGIN failure/i"; default_proto: tcp; default_dst_port: $IMAP_PORT; classtype: brute-force; parse_src_ip: 1; xbits: set,brute_force,track ip_src, expire 21600; after: track by_src, count 5, seconds 300; threshold: type suppress, track by_src, count 1, seconds 300; program: imapd*; sid:5002947; rev:4;)