FTP ‘connection timed out’

Ftp suddenly goes off and got ‘connection timed out’ before even connected
To determine what’s wrong with FTP :

• take a look /var/log/messages file for detailed error reports.
• the server hostname may not be resolved. In this case you should put the record like “SERVER_IP SERVER_HOSTNAME” into /etc/hosts.
• Make sure that inetd/xinetd is running.If inetd/xinetd is not running you also may be experiencing problems with sending mail (SMTP). Easy checking by sending mail. Or do :
  ps -aux | grep inetd
  or
  ps -aux | grep xinetd
• Check following configuration in /etc/proftpd.conf :
  
IdentLookups Off
UseReverseDNS Off

No problem found in the log, the server hostname resolved, i don’t have a problem sending email so i’m pretty sure that inetd/xinetd is running, proftpd.conf is correct. Something must blocked out FTP.
Last solution : Check firewall settings to be sure that ftp ports are opened.

Note : this can be tricky in plesk, since its firewall modules says it’s opened. Check a system firewall.