D-Link 800 - DFL 800 - Security Appliance, Руководство пользователя

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• Restricting access through the VPN to needed services only, since mobile computers are
vulnerable.
• Creating DMZs for services that need to be shared with other companies through VPNs.
• Adapting VPN access policies for different groups of users.
• Creating key distribution policies.
Endpoint Security
A common misconception is that VPN-connections are equivalents to the internal network from a
security standpoint and that they can be connected directly to it with no further precautions. It is
important to remember that although the VPN-connection itself may be secure, the total level of
security is only as high as the security of the tunnel endpoints.
It is becoming increasingly common for users on the move to connect directly to their company's
network via VPN from their laptops. However, the laptop itself is often not protected. In other
words, an intruder can gain access to the protected network through an unprotected laptop and
already-opened VPN connections.
Placement in a DMZ
A VPN connection should never be regarded as an integral part of a protected network. The VPN
firewall should instead be located in a special DMZ or outside a firewall dedicated to this task. By
doing this, the administrator can restrict which services can be accessed via the VPN and ensure that
these services are well protected against intruders.
In instances where the firewall features an integrated VPN feature, it is usually possible to dictate
the types of communication permitted and NetDefendOS VPN has this feature.
9.1.4. Key Distribution
Key distribution schemes are best planned in advance. Issues that need to be addressed include:
• How will keys be distributed? Email is not a good solution. Phone conversations might be
secure enough.
• How many different keys should be used? One key per user? One per group of users? One per
LAN-to-LAN connection? One key for all users and one key for all LAN-to-LAN connections?
It is probably better using more keys than is necessary today since it will be easier to adjust
access per user (group) in the future.
• Should the keys be changed? If they are changed, how often? In cases where keys are shared by
multiple users, you may want to consider overlapping schemes, so that the old keys work for a
short period of time when new keys have been issued.
• What happens when an employee in possession of a key leaves the company? If several users are
using the same key, it should be changed.
• In cases where the key is not directly programmed into a network unit, such as a VPN firewall,
how should the key be stored? On a floppy? As a pass phrase to memorize? On a smart card? If
it is a physical token, how should it be handled?
9.1.5. The TLS Alternative for VPN
If secure access by clients to web servers using HTTP is the scenario under consideration, then
using a D-Link Firewall for TLS termination can offer an alternative "lightweight" VPN approach
that is quickly and easily implemented. This topic is described further in Section 6.2.9, “The TLS
9.1.4. Key Distribution Chapter 9. VPN
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