Mac Net Manage 101
Volume Number: 15
Issue Number: 7
Column Tag: Network Management
Mac Network Management 101
By John O'Fallon, Maxum
Edited by Ilene Hoffman
Private TCP/IP Networks
Private TCP/IP networks aren't just for the security-conscious network
administrator. In fact, almost any Web Developer, Network Administration, or Site
Designer can use private networks to:
• Test the latest version of a Web server or a new plug-in at home or on a
laptop.
• Connect a small LAN to the Internet using a single Mac with a modem and a
PPP connection.
• Create a small test network that is logically separate from your
production LAN.
• Control Internet access by disabling or limiting certain Internet services
or capabilities on an entire LAN.
• Simplify network management and assign static addresses to clients
instead of using DHCP for testing, intranet applications or tracking.
• Protect a local network from external Internet users.
Private networks allow you to do all of the above, and on the Mac, it is surprisingly
easy. Even if none of the capabilities suggested above appeal to you (and I doubt that's
possible, given the subject matter of the fine periodical you now hold in your hands)
sit back and read on. If nothing else, you'll find out about some of the cooler new
features of Mac networking (Open Transport, from here on called simply OT).
Since we're talking about the newest features of OT, be sure you are using OT 1.3 or
greater. Any version of OT that shipped with Mac OS 8.1 or greater will be just fine.
The "Bogus" Setup
In the next few pages, we're going to build a private (or what I refer to as a "bogus")
TCP/IP network. Clients on our network will have full Internet access, or, if we
choose, only partial access. Furthermore, these clients will peacefully coexist with
"real" client workstations on the same physical network, if any physical network
exists at all.
We begin with a lone workstation, and not an Ethernet cable in sight...
Let's take the case where you would like to run two TCP/IP applications, say a Web
server and a Web browser, on the same Macintosh, with no connection to the Internet
or LAN. When I'm on the road and I want to test my latest WebStar Plug-In or Rumpus
tweak, I do this all the time on my PowerBook,. Configuring Open Transport so that a
Mac can use TCP/IP applications locally is so easy, most people don't believe me when
I tell them how to do it.
Start by opening the TCP/IP control panel, and then select "AppleTalk (MacIP)" as the
"Connect Via" setting. Set the "Configure" field to "Using Mac IP Manually", and then
enter an IP address. The IP address range beginning "192.168." is traditionally used,
and is reserved. With OT, you can use anything except "0.0.0.0" (which may actually
work but is special, so don't use it). For now, enter "192.168.1.3.
Finally, blank all the other fields and close the TCP/IP control panel. Don't worry
about the subnet mask, the router address, DNS, or anything else. Just close the
window. OT gives you a warning that it is going to pick some defaults for you. It does a
good job, so let OT use its defaults and click "Continue.
Figure 1. The TCP/IP Control Panel, Configured and Ready
Now fire up a TCP/IP server and client. You can use a Web server (Web Sharing,
WebStar, WebTen, etc.) and any Web browser for testing. Launch the server, then
launch the client and attempt to connect using the IP address you specified. Enter
"http://192.168.1.3/" in the location field and press return. Depending on how you
have your Web server configured, you should get a Web page served up. Even if you get
an error, it should be a "file not found" page delivered from the server, this indicates
that your "network" is up and running.
For Macs connected to an Ethernet network, you can also select "Ethernet" in the
"Connect Via" field. Again, make sure the "Configure" field is set to "Manually" and that
the made-up IP address is the only other field entered. This method should be used for
any Mac connected to an Ethernet LAN, and will also work on G3-based PowerMacs and
some PowerBooks (depending on your Ethernet driver) even when they aren't
connected. The benefit of this configuration is that multiple Macs connected to the same
Ethernet LAN will be able to communicate, as we will see in the next section.
Extending Bogusness to the Network