Which tactic is described as enabling access when firewall rules restrict inbound connectivity?

• A. Running vulnerability scanners only from the internal network
• B. Using a relay or tunneling technique to bypass inbound restrictions
• C. Bypassing authentication with default credentials
• D. Performing port knocking from the external network

Answer: (B)

When firewall rules restrict inbound connections, you can still reach systems by creating a tunnel or relay through an externally reachable host. By establishing an outbound connection to a control host you own and setting up a tunnel (such as an SSH reverse tunnel, a VPN, or a proxy), traffic to the target is carried inside that allowed channel. The firewall is more likely to permit the outbound connection and the related inbound traffic on the tunnel, so you gain access even though direct inbound access is blocked. Port knocking can open a port in some setups, but it depends on specific firewall behavior and is less reliable than a tunnel-based approach.