Network Security Technologies and Protocols: AAA, VPN and Firewall

Network security covers issues such as network communication privacy, information confidentiality and integrity over network, controlled access to restricted network domains and sensitive information, and using the public network such as Internet for private communications. To address those issues, various network and information security technologies are developed by various organizations and technology vendors. Here are a summary of the technologies:

AAA: Authorization, Authentication and Accounting is a technology for intelligently controlling access to network resources, enforcing policies, auditing usage, and providing the information necessary to bill for services. Authentication provides a way of identifying a user, typically by having the user enter a valid user name and valid password before access is granted. The authorization process determines whether the user has the authority to access certain information or some network sub-domains. Accounting measures the resources a user consumes while using the network, which includes the amount of system time or the amount of data a user has sent and/or received during a session, which could be used for authorization control, billing, trend analysis, resource utilization, and capacity planning activities. A dedicated AAA server or a program that performs these functions often provides authentication, authorization, and accounting services.

VPN: Virtual Private Network is a technology allowing private communications by business and individuals, such as remote access to corporate network, using a public telecommunication infrastructure, such as the Internet. A virtual private network can also be a specially configured network over the public network infrastructure that is only used by one organization. Various network-tunneling technologies such as L2TP are developed to reach this goal. Using encryption technologies such as IPsec could further enhance information privacy over public network and virtual private network.

Firewall: It is a software program or hardware device that filters the information coming through the Internet connection into a private network or computer system. Firewalls use one or more of three methods to control traffic flowing in and out the network:

• Packet filtering - Packets are analyzed against a set of filters. Packets that make it through the filters are sent to the requesting system and all others are discarded.
• Proxy service - Information from the Internet is retrieved by the firewall and then sent to the requesting system and vice versa.
• Stateful inspection - compares certain key parts of passing through packets to a database of trusted information. Outgoing information from inside the firewall is monitored for specific defining characteristics, and then incoming information is compared to these characteristics. If the comparison yields a reasonable match, the information is allowed through. Otherwise it is discarded.