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Modify IP Block Checking Time Interval in CSF

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If you are unable to log into cPanel for the first time, please refrain from attempting to do so repeatedly. Doing this may lead to IP blocking if you continuously try to log in with incorrect login details, such as attempting to log in 20 times within a 5-minute period. To avoid this, make sure that you are using the correct login details provided in the Welcome Email Information that was sent to the email account you used to sign up.

Reasons for Blocking IP Address

Block due to unsuccessful POP3/IMAP login attempts
If you start receiving errors or popup windows related to failed IMAP/POP3 authentication in your email client, it is likely that the login credentials are incorrect or outdated. In such cases, the email client will keep trying to access the mail server multiple times, which will eventually result in a permanent IP block.

Block due to unsuccessful SMTP login attempts
This type of block occurs when the SMTP authentication details are incorrect, preventing you from sending emails from your email client. Ensure that the SMTP login credentials are accurate and valid.

Incorrect email client settings
IP blocking may also occur due to incorrect email client settings.

Failed FTP/SSH login
Ensure that your FTP client is using the correct login details and appropriate settings. Additionally, using the wrong port number to log in can also result in IP blocking by the firewall.

Failed web page login
Another possibility for IP blocking is if there is an authentication form or protected file on the website that requires login details. It is your responsibility to ensure that you use the correct and valid login credentials.

Resetting the IP Block Time Interval

1) Access the server via SSH.

2) Open the CSF configuration file “csf.conf” in any text editor.

# vi /etc/csf/csf.conf

3) Modify the following values (in seconds):


Changing the above value will adjust the time interval for failed login attempts from an IP address to the server.


Changing the above value will adjust the time interval for the total number of connections from an IP address to the server.

CT_BLOCK_TIME = “1800”

Changing the above value will adjust the IP address block time interval, during which the IP will remain blocked.

4) Restart the CSF daemon to apply the changes. Run the following command to restart CSF.

# csf -r

If you need further assistance, please contact our support department.

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