Attribute Lists

An attribute list contains a set of attributes. The allowed lists are:

request: Attributes in the incoming request packet.
reply: Attributes in the outgoing reply packet.
control: Attributes in the internal "control" list that is associated with the request.

The control attributes are used to manage how the request is processed. These attributes are never sent in any packet.
session-state: Attributes which are maintained across multi-packet exchanges.

There must be a dot . after the list name and before the attribute name. This syntax helps the server to distinguish between list names and attribute names.

In version 3, there were additional lists such as proxy, proxy-reply, and coa. These lists have been removed in version 4. See the subrequest keyword for how to create child requests.

With the exception of session-state, all of the above lists are ephemeral. That is, they exist for one packet exchange, and only one packet exchange. When a reply is sent for a request, the above lists and all attributes are deleted. There is no way to reference an attribute from a previous packet. We recommend using a database to track complex state.

In some cases, requests are associated a multi-packet exchange. For those situations, the session-state list is automatically saved when a reply is sent, and it is automatically restored when the next packet in sequence comes in. Once the packet exchange has been finished, the session-state list is deleted.

In some cases, there is a parent-child relationship between requests. In those situations, it is possible for the policy rules in the child to refer to attributes in the parent. This reference can be made by prefixing the <list> name with the parent qualifier. The key word outer is also a synonym for parent. If there are multiple parent-child relationships, the parent qualifier can be repeated.

There is, however, no way for the parent to refer to the child. When the child is running, the parent is suspended. Once the child finishes, it is deleted, and is no longer accessible to the parent.

Examples

&parent.request.User-Name
&parent.reply.Reply-Message
&parent.parent.session-state.Filter-Id