Specifications

48
Don’t advertise what you have. The more the attacker knows about your installation the easier it is
to find a weakness. All systems have weaknesses.
21 Laptop – Connecting from Anywhere
We use a laptop at our home office, in the office and while traveling. This means it needs to connect in
three different network environments.
Location specific network settings are sprinkled all over Windows and within various applications. This
makes it hard to move a computer between locations. One of the reasons we converted from proxy to NAT
was to eliminate configuring applications to use location specific proxy. NAT is largely transparent to
applications.
Even though we attempted to minimize the differences between locations we still wound up with several
site-specific settings. The solution was to use NetSwitcher to effect location specific changes. The table
below shows the various network setting and which ones need to be changed by NetSwitcher.
@Home
@Office
On the road
IP Address
DHCP
DHCP
Dialup PPP DHCP
User Authentication
Windows Client
NT Domain
Windows Client
Office File Shares
VPN
NT permissions
VPN
SOHO File Shares
Peer-to-peer
N/A
N/A
Default Printer
Local network printer
Local network printer
Directly attached printer
Time
K9 client
N/A
N/A
Email receive
3 POP accounts
3 POP accounts
3 POP accounts
Email send
Authenticated SMTP
Authenticated SMTP
Authenticated SMTP
Usenet
Authenticated dialup
account
DSL account
Authenticated dialup
account
Authenticated dialup
account
IE home page
Private web server
Biz home page
Dummy home page on
laptop
Note: Netswitcher modifies entries highlighted in yellow.
Figure 27 Laptop configuration table
21.1 Netswitcher
NetSwitcher works by modifying settings in the Windows Registry. It can control most network settings
and select the default printer.
This left us with the need to change the default home page in the browser. A FAQ on the NetSwitcher web
page describes how to create extension by using the registry editor, REGEDIT, to extract registry entries
and create scripts that NetSwitcher executes. This has worked extremely well. The only down side is that it
is easy to get confused by the hack. If you go in and make a change, the change goes into effect and all is
well. The next time you change location then NetSwitcher overwrites the change. After a little head
scratching you remember what you did and all is well, but this is not something to roll out on a large scale.
When Windows shuts down the NetSwitcher dialog box pops up. This allows the correct configuration to
be selected for the next boot.