Final answer:
SSL/TLS is the secured tunneling protocol that can often cross firewalls where IPsec is blocked, as it uses port 443, which is generally allowed through firewalls for secure web traffic.
Step-by-step explanation:
The secured tunneling protocol that could cross firewalls where IPsec might be blocked is SSL/TLS. This protocol operates at the application layer and encapsulates network traffic, typically over port 443, which is commonly allowed through firewalls for HTTPS traffic. It is widely used to secure communications over the internet, including web browsing, email, instant messaging, and voice over IP (VoIP). Unlike IPsec which operates at the network layer and may be blocked by strict firewall rules, SSL/TLS has a better chance of traversing firewalls without being stopped.