We have an application on our work premises that people externally use VPN to access. The port has been set to 'ANY'. However, if I wanted to lock this port down, I have some issues as there is no documentation on what the ports are. When I look at the firewall logs, I can see that the source port always changes but the destination port stays the same. What does this mean if the source port changes but the destination port is the same? I assume the destination port is the port on the application on our side and therefore we can lock the VPN ports down to this destination port?
Thanks for helping