This article answers the question of whether internet access is one of the GFI LanGuard requirements for vulnerability scanning.
Internet access is NOT a requirement of GFI LanGuard to perform vulnerability scanning on a local network. It can operate normally in highly secured networks not connected to the internet.
Refer to the Required Settings to Scan a Machine Using GFI LanGuard article for more information as to what the actual requirements are, and to the Verifying Required Network Connectivity and Security Permissions for GFI LanGuard Operations as to how to verify the requirements.
Internet access is only required when:
Scanning remote targets that are not directly connected to the local network.
System administrators must ensure that Internet communications are secured using high-security mechanisms, such as VPNs and other forms of tunneling protocols, when scanning remote targets connected to a public network, such as the Internet.
Upgrading or downloading the latest definitions and the GFI LanGuard library/product updates.
There is a solution for such a scenario as well, refer to Upgrading GFI LanGuard 12 in a Secure Network article for details.