Unable to connect to Plesk server over FTP: FAIL: ftp per_source_limit

Symptoms

• Unable to connect to Plesk server over FTP with the following error is shown in an FTP client:

  Error: Could not connect to server

• It is not possible to download a big amount of files via FTP.

• The following error is found in the file /var/log/messages (/var/log/syslog on Debian/Ubuntu):

  FAIL: ftp per_source_limit from=203.0.113.2

Cause

The connection limit per IP address is exceeded.

Resolution

1. Connect to the server via SSH

2. Edit file /etc/xinetd.d/ftp_psa by adding the next line (in bold):

   ...
   instances = UNLIMITED
   per_source = UNLIMITED
   server = /usr/sbin/in.proftpd
   ...

3. Restart the xinetd service:

   # service xinetd restart