19216811.liveReference Manual for the MR814 v3 Cable/DSL Wireless Router
B-10
Network, Routing, Firewall, and Basics
202-10039-01
IP Configuration by DHCP
When an IP-based local area network is installed, each computer must be configured with an
IP address. If the computers need to access the Internet, they should also be configured with a
gateway address and one or more DNS server addresses. As an alternative to manual
configuration, there is a method by which each computer on the network can automatically obtain
this configuration information. A device on the network may act as a Dynamic Host Configuration
Protocol (DHCP) server. The DHCP server stores a list or pool of IP addresses, along with other
information (such as gateway and DNS addresses) that it may assign to the other devices on the
network. The MR814 v3 router has the capacity to act as a DHCP server.
The MR814 v3 router also functions as a DHCP client when connecting to the ISP. The firewall
can automatically obtain an IP address, subnet mask, DNS server addresses, and a gateway address
if the ISP provides this information by DHCP.
Internet Security and Firewalls
When your LAN connects to the Internet through a router, an opportunity is created for outsiders
to access or disrupt your network. A NAT router provides some protection because by the very
nature of the process, the network behind the router is shielded from access by outsiders on the
Internet. However, there are methods by which a determined hacker can possibly obtain
information about your network or at the least can disrupt your Internet access. A greater degree of
protection is provided by a firewall router.
What is a Firewall?
A firewall is a device that protects one network from another, while allowing communication
between the two. A firewall incorporates the functions of the NAT router, while adding features for
dealing with a hacker intrusion or attack. Several known types of intrusion or attack can be
recognized when they occur. When an incident is detected, the firewall can log details of the
attempt, and can optionally send E-mail to an administrator notifying them of the incident. Using
information from the log, the administrator can take action with the ISP of the hacker. In some
types of intrusions, the firewall can fend off the hacker by discarding all further packets from the
hacker’s IP address for a period of time.