We strongly advise that your instance(s) of Server Check are secured with a firewall where possible.

Server Check requires internet access for our update and licensing services to operate correctly, however we recognise that your setup may require internet access to be restricted to certain IP addresses. Server Check update and licensing services operate on the following network addresses:

81.187.25.96/28
34.133.202.100

Please allow these addresses in your firewall along with your other trusted IP addresses.