You should whitelist the following FQDN: scanners.pentest-tools.com. This hostname resolves to multiple IP addresses used by our scanning servers: 139.162.221.245 88.80.191.29 139.162.202.208 212.71.244.176 139.162.209.251 212.71.255.152 176.58.123.114 178.79.150.162 139.162.192.40 139.162.224.195 109.74.197.184 178.79.163.66 178.79.183.178 178.79.135.133 212.71.238.216 80.85.84.168 178.79.168.123 139.162.249.83 213.52.129.114 213.52.129.87 213.52.129.94 139.162.206.50 139.162.209.125 139.162.209.101 85.159.208.15 178.79.188.46 139.162.196.182 85.159.208.197 151.236.220.252 176.58.123.12 139.162.207.246 143.42.100.222 139.144.154.251 139.144.155.32 178.79.135.30 212.71.254.62 88.80.191.254 176.58.117.166 88.80.190.42 143.42.109.254 139.162.253.24 vpn.pentest-tools.com 212.71.255.115 Also available as a IPv4 text list.