System information

C
H A P T E R
4
Configuring Cisco VPN 3000
for Remote Access Using
Preshared Keys
From a procedural perspective, it is easier to configure the Cisco VPN 3000 Concentrator
Series for remote access using preshared keys. While the alternative method is to use
the services of a Certificate Authority (CA), that method entails additional steps. Using
preshared keys, the client only needs to know the address of the VPN concentrator and
the shared secret key.
While VPN configuration is relatively easy with preshared keys, this manual process does
not scale well for large implementations. The VPN administrator must provide the pass-
word and implementation instructions to prospective users. This could be accomplished by
preconfiguring client software on a floppy disk or CD-ROM, but even that process can be
labor intensive in large implementations.
Once all of your users have successfully configured their remote systems with the current
shared key, the process of changing passwords periodically, as every good security plan
requires, would require notifying all users of the new password and providing modification
instructions. You can imagine how it would be easy to forget about this important security
consideration.
While scaling VPN implementations can be better handled by using CA support and digital
certificates, preshared keys are easy to implement and can be used in many applications.
This chapter discusses the process of implementing Internet Protocol Security (IPSec)
using preshared keys on the Cisco VPN 3000 Series Concentrators. The clever graphical
user interface (GUI) makes the implementation process easy.
How to Best Use This Chapter
By taking the following steps, you can make better use of your time:
• Keep your notes and answers for all your work with this book in one place for easy
reference.
•
Take the “Do I Know This Already?” quiz, and write down your answers. Studies
show retention is significantly increased through writing facts and concepts down,
even if you never look at the information again.
•
Use the diagram in Figure 4-1 to guide you to the next step.
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