Desktops should also have virus protection installed and a mechanism for user controlled screen lock. Each network interface and each communications path is potentially vulnerable. Data transmitted over a network is subject to capture and modification. At Stanford, the SUNet network is an open network, meaning that there is no firewall between the SUNet backbone and the Internet, and in general no firewalls between departmental networks and the SUNet backbone. Applications must protect any transmitted data with methods appropriate to its sensitivity level.
Protection includes both integrity checks such as checksums and data encryption.
Plans should be made to apply the selected protection method to all application use scenarios, including remote use, connections via third-party network service providers, and mobile use. Keep in mind that data is often transmitted between distributed application processes as well as between users and servers. A secure network is defined as a network where only trusted hosts are attached to a particular subnet and all communication of a sensitive nature is restricted to that subnet. This is difficult to implement because it requires every machine to be secure and access to the network to be restricted in some fashion. The network in Forsythe, for example, should not be considered to be a secure network.