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Knowledgebase: FTP/SFTP
Error: Too many open connections for your IP?
Posted on 25 January 2004 01:28 AM
Question:

I am receiving an error when attempting to connect by FTP to my account--
"Too many open connections for your IP"

Here is an example FTP logfile:
STATUS:> Connecting to www.mydomain.com
STATUS:> Connecting to www.mydomain.com (ip = 69.5.XXX.XX)
STATUS:> Socket connected. Waiting for welcome message...

220-TwoFTPD server ready.
220 Authenticate first.
STATUS:> Connected. Authenticating...
COMMAND:> USER xxxxxx
331 Send PASS.

COMMAND:> PASS ********

421 Too many open connections for your IP.
ERROR:> Password not accepted
ERROR:> Can't login. Disconnecting...

What's going on, I am not running any other processes?

Answer:

Due to security restrictions in the FTP server, we only allow 4 concurrent userid connections per IP, and 8 total per userid.

This would ensure that even if your webmaster (or anyone else with authorized FTP access) had tied up 4 of your FTP connection slots, that you would still have 4 remaining to connect and not be blocked by the other person.

The implementation of the security restrictions was to curtail those running heavy web cams and slurping up a bunch of connection slots which would deny others fair use of the FTP server...

If you do encounter the above restriction, then most likely you opened a connection and did not properly close the communications, like forcibly terminating the FTP client.

Hopefully this will help you to understand what that message means and how to avoid it in the future. After you receive that message, the best you can do is wait for the auto-timeout to kill your defunct connection slot in 15 minutes.

For the future, we would suggest limiting your FTP program to three connections if your FTP client offers that option or an even better option would be to switch to the use of SFTP instead of FTP for file transfers. SFTP, which is supported by many current file transfer programs, is a secure file transfer mechanism running over SSH that offers security that FTP does not and also avoids many of the problems caused by FTP.