Once again, these functions require cryptographically secure methods but in this instance the coding is used to provide a unique digital signature as opposed to encrypting the information. This also includes protection against the resubmission of duplicated information, which could be used to create confusion and inconsistency within the network. This form of protection must be provided as an integrated feature or the protocols and must be capable of supporting time stamped message passing to ensure time related fidelity of the transfer of the information. In most cases these systems make heavy use of password protection and access privilege tables which map the logical user to a physical location and so are dependent on the network adapter addresses. From the point of view of virus protection it is important to consider that both accidental as well as intentional infection must be avoided.
Prevention is better than cure.
However, the current level of protection coupled with the pressures of access mean that in all but the most vigilant environments it is impossible to prevent infection completely. This same network can also be used as a general test bed in which all network upgrades and so on can be tested before attempting them on the real network. Total prevention entails the sealing of all external drives and the isolation of external network interfaces, for example routers. Read only access permits users to insert their disks but prevents them from storing this information on the network based servers. Clearly, both techniques have advantages as well as serious disadvantages.