Hands-on hardware: DSL / cable modem routers

By Steve Antonoff, ITworld.com |  Networking

The important differences between the boxes are the way they handle port address
translation
(PAT) for incoming traffic, the inclusion of a demilitarized
zone
(DMZ), and the completeness of the DHCP.

Of the three, only Hawking allows DHCP reservations -- an address assigned to a
network adapter based on its permanent MAC address. This allows servers, for example,
to use DHCP to get their addresses without the address bouncing around. In my network,
I set up reservations for all permanent, resident PCs. In this case, DHCP is used to
change the configuration when necessary and to document each computer's IP address.
Transient PC's get an address from the pool of unassigned addresses.

For incoming traffic, all three devices provide some form of rerouting based on IP
port number. The Linksys and the Trendware, however, force the connection to the
internal computer to use the same port number as the incoming request. Hawking allows
the internal port to differ from the original. For example, if you have two machines
behind the router that provide WWW service, both use port 80. You can tell the Hawking
to reroute port 80 requests to one machine, using port 80, while requests on port 81
can be routed to the other machine but mapped to port 80. The same holds true for
Telnet, FTP, etc.

Finally, if you use one computer for lots of stuff, it might be helpful to just open
it up to any port request that it will process. Example: You have one machine that
does FTP, HTTP, Telnet, POP3, and SMTP for employees connecting over the Internet.
Rather than program every required port into the PAT table, set the machine up as the
DMZ machine; all requests to ports not translated by PAT will be sent to the
DMZ computer.

I would like to see a DNS service for the internal network, but none of these
devices provide it. You'll need to either put HOSTS tables on all the computers for
naming of the internal network or run WINS or DNS on a server. I'm keeping my DNS and
WINS on the prime server.

Conclusion

If you have DSL or cable modem service, these devices are worth the small investment.
I'd stay away from the Trendware, at least until they fix the problems I have
described. The street prices for the Hawking Technology and Linksys boxes are
similar.

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