D-Link 800 - DFL 800 - Security Appliance, User Manual

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• FORM - The user is presented with an HTML page for authentication which is filled in and
the data sent back to NetDefendOS with a POST.
• BASICAUTH - This sends a 401 - Authentication Required message back to the browser
which will cause it to use its own inbuilt dialog to ask the user for a username/password
combination. A Realm String can optionally be specified which will appear in the browser's
dialog.
FORM is recommended over BASICAUTH because in some cases the browser might hold the
login data in its cache.
• If the Agent is set to HTTPS then the Host Certificate and Root Certificate have to be chosen
from a list of certificates already loaded into NetDefendOS.
Setting Up IP Rules
HTTP authentication cannot operate unless a rule is added to the IP rule set to explicitly allow
authentication to take place. If we consider the example of a number of clients on the local network
lannet who would like access to the public Internet through the wan interface then the IP rule set
would contain the following rules:
Action Src Interface Src Network Dest Interface Dest Network Service
1 Allow lan lannet core lan_ip http-all
2 NAT lan trusted_users wan all-nets http-all
3 NAT lan lannet wan all-nets dns-all
The first rule allows the authentication process to take place and assumes the client is trying to
access the lan_ip IP address, which is the IP address of the interface on the D-Link Firewall where
the local network connects.
The second rule allows normal surfing activity but we cannot just use lannet as the source network
since the rule would trigger for any unauthenticated client from that network. Instead, the source
network is an administrator defined IP object called trusted_users which is the same network as
lannet but has additionally either the Authentication option No Defined Credentials enabled or has
an Authentication Group assigned to it (which is the same group as that assigned to the users).
The third rule allows DNS lookup of URLs.
Forcing Users to a Login Page
With this setup, when users that are not authenticated try to surf to any IP except lan_ip they will
fall through the rules and their packets will be dropped. To always have these users come to the
authentication page we must add a SAT rule and its associated Allow rule. The rule set will now
look like this:
Action Src Interface Src Network Dest Interface Dest Network Service
1 Allow lan lannet core lan_ip http-all
2 NAT lan trusted_users wan all-nets http-all
3 NAT lan lannet wan all-nets dns-all
4 SAT lan lannet wan all-nets
all-to-one
127.0.0.1 http-all
5 Allow lan lannet wan all-nets http-all
The SAT rule catches all unauthenticated requests and must be set up with an all-to-one address
mapping that directs them to the address 127.0.0.1 which corresponds to core (NetDefendOS itself).
8.2.7. HTTP Authentication Chapter 8. User Authentication
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