Network equipment, although self running, requires monitoring and maintenance, not only for performance but also for security purposes. Computer security needs to be applied at all levels of network and application implementation, including, planning, risk assessment, design, audit, testing, and maintenance. Computer security responsibility must be shouldered by various level of personnel in an organization, from the level of CEO, Information Security Officers, IT managers, system developers, system integrators, network and system administrators until the users. Policy and procedures must be applied and measured for effectiveness. Monitoring of network and system activities is key in detecting anomalies that may be due to security breach.
Firewall is a type of network perimeter defense.
It protects the network from external threats however it does not help in deterring internal threats. There are two types of firewall, one which functions like a packet filter, and one that functions like a proxy. Depending on the needs of the network, any one of these types of firewall, if applied correctly would be effective in deterring external threats. However, there are attacks that can bypass the firewall, since firewalls may not be intelligent enough to block attacks that seem like genuine traffic request. Web servers, mail servers and Domain Name servers are prime targets of attacks.