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Protector keeps its list of bad IP addresses in a file names "badips" followed by 6 hex characters unique to your system.
If you are using XOOPS 2.5.9, the "badips" file is found in the "xoops_data/protector/" directory.
In earlier XOOPS versions, the file will be in the "xoops_lib/modules/protector/configs" directory.
Deleting that file, or editing it to remove the line with you IP address should end the ban.