HP VPN Firewall Appliances Access Control Configuration Guide

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Configuring the portal server detection function
During portal authentication, if the communication between the access device and portal server is
broken, new portal users are not able to log on and the online portal users are not able to log off. To
address this problem, the access device needs to be able to detect the reachability changes of the portal
server quickly and take corresponding actions to deal with the changes. For example, once detecting
that the portal server is unreachable, the access device allows portal users to access network resources
without authentication. This function is referred to as portal authentication bypass. It allows for flexible
user access control.
With the portal server detection function, the device can detect the status of a specific portal server. The
specific configurations include:
1. Detection methods (you can choose either or both)
{ Probing HTTP connections—The access device periodically sends TCP connection requests to
the HTTP service port of the portal servers configured on its interfaces. If the TCP connection with
a portal server can be established, the access device considers that the probe succeeds (the
HTTP service of the portal server is open and the portal server is reachable). If the TCP
connection cannot be established, the access device considers that the probe fails and the
portal server is unreachable.
{ Probing portal heartbeat packets—A portal server that supports the portal heartbeat function
(only the IMC portal server supports this function) sends portal heartbeat packets to portal
access devices periodically. If an access device receives a portal heartbeat packet or an
authentication packet within a probe interval, the access device considers that the probe
succeeds and the portal server is reachable. Otherwise, it considers that the probe fails and the
portal server is unreachable.
2. Probe parameters
{ Probe interval—Interval at which probe attempts are made.
{ Maximum number of probe attempts—Maximum number of consecutive probe attempts
allowed. If the number of consecutive probes reaches this value, the access device considers
that the portal server is unreachable.
3. Actions to be taken when the server reachability status changes (you can choose one or more)
{ Sending a trap message—When the status of a portal server changes, the access device sends
a trap message to the NMS. The trap message contains the portal server name and the current
state of the portal server.
{ Sending a log—When the status of a portal server changes, the access device sends a log
message. The log message indicates the portal server name and the current state and original
state of the portal server.
{ Disabling portal authentication (enabling portal authentication bypass)—When the device
detects that a portal server is unreachable, it disables portal authentication on the interfaces
that use the portal server (allows all portal users on the interfaces to access network resources).
When the device receives from the portal server portal heartbeat packets or authentication
packets (such as logon requests and logout requests), it re-enables the portal authentication
function.
You can configure any combination of the configuration items described as needed, with respect to the
following: