What's A Dmz; What's A Nat - Polycom ViaVideo Technical Reference

Chapter 3

What's a DMZ?

What's a NAT?

© Polycom, Inc. 2001
Most firewalls provide DMZ configuration as a way to allow high
availability access for web servers and video communications
servers (that's your PC running ViaVideo) while providing firewall
access for the other devices in the network. A DMZ is not a physical
location, but is instead a way to configure your network so that the
devices that are "in" the DMZ are served by the router, but are
outside the protection of the firewall. Devices in the DMZ then
communicate with the other devices in the internal network through
the firewall.
This solution creates a "safe zone" within your internal network by
effectively placing the video communications server outside of the
firewall's protection. In this way, no unauthorized connections are
allowed within the firewall-protected zone, and the video
communications server is allowed free access to the internet. Note
that this configuration leaves the video communications server
without protection from external sources.
Setting up your ViaVideo's computer in a DMZ is the quickest way to
configure your ViaVideo to run while using a firewall. For more
information about configuring your video communications server in
a DMZ, see "Router With Firewall, Using a DMZ" on page 14.
A Network Address Translator (NAT) is a set of services on the
router that allow you to operate a local network of devices, each with
its own locally unique IP address, while communicating to the
Internet through a router which presents a single, globally unique IP
address to the outside world. Most small business and home office
(SOHO) routers provide NAT services.
The NAT ensures that outgoing packets have a globally valid IP
address, and that incoming packets go to the right device by
translating between the internal IP address and the external IP
address, owned by the router. This also adds an extra level of
security by effectively masking the internal network behind a single
external IP address.
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Network Connection
ViaVideo Technical Reference