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Identity-based policies

Identity based policies are ones in which there is the additional component of either an account identity or device identity. The inclusion of one or both of these components adds an extra dimension of complexity to working with these policies in the context of the other policies so while the extra security and granularity of control are beneficial, extra care must be taken when configuring the policies themselves and how they are positioned in the policy sequence. The actual configuration of these identities are explained in detail in the Authentication Handbook.

Identity-based security policies are usually configured for IPsec or SSL VPN traffic since this type of traffic usually requires authentication from network users.

Identity-based policy positioning

In non-identity based policies, if non of the 6 mandatory policy parameters matches the header of the traffic packets the parameters are compared against the next policy in sequence. Because those parameters are mandatory there is always a value to test against and whether or not the policy applies is certain. The fact that the identity parameters are not required makes knowing whether or not the correct policy will be applied less obvious.

Originally, the identity aspect of a policy was an entire sub-policy checking sequence within each policy, including its own 0 policy at the end of the sequence. If all of the other parameters match the policy would then compare the traffic's identity with the list of identity groups in the policy starting at the beginning of the sequence and going through them until an identity was found that matched and then the rules for that identity group would be applied. If the traffic's identity did not match any of those listed in the policy it go to the last identity in the policy would be everyone and the Action would be deny.

The identity aspects of policies have now been incorporated in a single flat configuration that makes them a fundamental part of the policy rather than something that is added to the policy. This is simpler and allows for more complex combinations of address identification, user authentication and device determination that were not possible with previous policy configurations. Both user groups and device groups can be part of the same policy. Because the identity aspects are optional, more flexibility in creating policies that use authentication is possible.

Identity fall through rules

The fall through rules for policies in 5.2 have changed so that they are more in keeping with the practices of other vendors. This makes it easier for users used to other firewalls to configure the policies and it also makes it simpler to convert the policies of other firewalls to be used on a FortiGate firewall.

Previously, if traffic reached an identity policy and the user or device was not a member of one of the groups specified it would fall through to the implicit deny all policy. This meant that any traffic that reached that policy would have to be authenticated and a member of one of the listed groups. If the 6 required parameters matched, the traffic would not be getting past this policy.

The approach is now to treat the the identity parameters, if they exist, the same as the other parameters, in that if they do not match any listed in the policy, the traffic drops down to the next policy.

Example:

There are three policies where all the parameters are the same except:

• Policy # 1 - Source User Group A is assigned profile A
• Policy # 2 - Source User Group B s assigned profile B
• Policy # 3 - Source User(s) and Source Device Type are empty

Traffic that matches all of the required parameters will be processed as follows:

• Traffic authenticated as being from User Group A will be processed by Policy # 1.
• Traffic authenticated as being from User Group B will be processed by Policy # 2.
• Traffic with no authenticated users will be processed by Policy # 3.
• Traffic authenticated as being from User Group C will be processed by Policy # 3.

In the methodology before FortiOS 5.2, traffic authenticated as being User Group B, User Group C or no authenticated user at all would have been stopped at Policy # 1.

The CLI command “fall-through-unauthenticated” that was added in 5.0.1 attempted to allow a process similar to this, but only applied to unathenticated traffic and not authenticated traffic that didn’t match the list of groups is the sub-policy. The current methodology is not subject to the same limitation and alleviates the need for the function of this command so the command has been removed from the CLI.

Implicit protocols

In previous versions of the firmware, the protocols that were used to authenticate such as HTTP, HTTPS, FTP, and Telnet, were supported on the policy whether or not they were included in the supported services. In 5.2, the protocol needed to authenticate needs to be included in the list of allowed services in order the the authentication to take place.

For example, if you have a VIP coming into your network that is for connecting to some security webcams located in your data center that use custom services or ports to connect to, if you are using an identity policy you would also have to include HTTP or HTTPS in the services list in order to actually authenticate.

Another formerly implicit protocol that is not supported automatically in 5.2 is port 53 (DNS). If you are limiting the services of a protocol to web based protocols such as HTTP or HTTPS don’t forget to to add DNS so that the domain names can be resolved.

 

When upgrading the firmware from version 5.0.x to 5.2.x, a policy with either an identity or device sub-policy will automatically convert from a single policy with sub-policies to a separate policy for each identity based sub-policy.