Only grant a few set of ip's acces to the admin panel.
Admin panel allowed IP's
Instructions :
1) Extract adminallow in the plugins folder. Preserve the directory structure of this archive.
2) open the file "sed_allowlist.sql" in wordpad or notepad, and replace the line "ENTER YOUR IP HERE" with your ip
3) Import the sql file via phpmyadmin
4) Go to Admin Panel > plugins > Admin Panel Allowed ip's > Install All
Managing the IP list :
1) After installation, go to Admin Panel > plugins > Admin Panel Allowed ip's.
2) Add , update or remove ip's