Internet Security And Firewalls - NETGEAR FVM318 Reference Manual

Reference Manual for the Model FVM318 Cable/DSL ProSafe Wireless VPN Security Firewall
When a PC accesses a resource by its descriptive name, it first contacts a DNS server to obtain the
IP address of the resource. The PC sends the desired message using the IP address. Many large
organizations, such as ISPs, maintain their own DNS servers and allow their customers to use the
servers to look up addresses.
IP Configuration by DHCP
When an IP-based local area network is installed, each PC must be configured with an IP address.
If the PCs 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 PC 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 FVM318 firewall has the
capacity to act as a DHCP server.
The FVM318 firewall 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.
B-10 Network, Routing, Firewall, and Wireless Basics