If you would like to allow a specific IP access to your server via the Plesk panel and/or SSH then you can configure this in the Plesk Firewall.

Please of the following:

1. Log into Plesk, click on "Tools and settings" and then select "Firewall"

2. Click on "Edit firewall configuration"

3. Firstly, to grant access to the Plesk Panel, click on the "Plesk administrative interface" rule.

4. This may be set to "Allow all", change this to "Allow from selected sources, deny from others"

5. Enter the IP address that you would like to grant access to the Plesk Panel in the the "Add IP address or network".

6. Click on OK, then click on "Apply configuration" - If you do not click this then any changes you have made will not be applied.

7. If you would also like to grant access via SSH, do steps 1 and 2 but on step 3 click on the "SSH (secure shell) server" rule. Then repeat steps 4-6.

Once you have done this you will have blocked all access to the Plesk Panel and SSH accept for the IP that you have entered.

If you would like to grant access to anybody with a username and password from any IP, simply select the "Allow all" option in Step 4.