NETWORKING ESSENTIALS - Security zones, Perimeter networks, and Firewalls
A perimeter network is
a small physical or virtual sub-network that
is set up between a company's private local area network,
or LAN, and untrusted networks such as the Internet.
It's called a perimeter network because
it's usually on the edge of a LAN.
This is often a physical structure that supports
the logical extranet concept that was previously covered.
A perimeter network allows
users outside of a company LAN,
to access specific services
located on that perimeter network.
The perimeter network might house a switch with
servers connected to it that offer web,
email or other services.
A firewall is a hardware device,
or a software program providing
security by segregating one part
of the network from another.
Firewalls are configured to use filtering rules that
allow only authorized network
traffic to pass through that.
They may filter based on type of traffic,
where the communication originates, or other criteria.
Firewalls are used to help protect
the network from malicious attack and unwanted intruders.
They are the most commonly used type of
security device in an organization's perimeter network.
Security devices such as firewalls
are the main defense for a company's network.
Whether they're LANs, wide area networks LANs,
intranets or extranets.
Perimeter networks can provide a physical barrier,
keeping certain information open to specific users or
the public while keeping
the rest of the organization's data secret.