These are devices which control connections between networks. They are set up to allow authorized access and prevent unauthorized access from the public network to business information on your private network. For intruders these will be the locked doors requiring more effort to gain access.
Security measures should be implemented when building and installing computers and network devices in order to minimise the number of inherent vulnerabilities. A secure configuration ensures each device discloses only the minimum information about themselves to internet and provide only the services required to fulfil their intended function.
The purpose of access control is to ensure that user accounts are assigned only to authorized individuals and at the appropriate level.
Computers connected or exposed to the internet can be infected with malware and dedicated software is required to monitor, detect and disable malware.
A patch management strategy is required to ensure the latest supported version of applications is used.