Today's letter of the day in the ABC's of Networking is "F".  "F" starts some great networking terms such as Failover, Floating addresses, Filters, FQDNs, Forwarding, and Flooding.  But none of those were exciting enough, so I opted to go with the "F" word of Firewall since a Firewall is a requirement in any modern network.

"F" is for Firewall

Firewall

Pronounced: fīr'wôl

A Firewall is used to represent any number of security schemes that prevent unauthorized users from gaining access to a computer network.  Typically a firewall is implemented as a device or set of devices configured to permit, deny, encrypt, or proxy between differing security domains based upon a set of rules or policies.  Firewalls come in the form of transparent hardware appliances as well as software that runs directly on end user devices.