3Com MSR 50 Series Configuration Manual page 1871

Troubleshooting Portal 1871
Solution
Use the display portal server command to display the key of the portal server on
the access device and use the portal server command to modify the key in
system view. Or view and modify the key of the access device on the portal server
to ensure their keys are consistent.
Incorrect Server Port Symptom
Number on the Access
After a user passes the portal authentication, you cannot force the user to log out
Device
by executing the portal delete-user command on the access device, but the user
can log out by using the disconnect attribute on the authentication client.
Analysis
When you execute the portal delete-user command on the access device to
force the user to log out, the access device actively sends a REQ_LOGOUT
message to the portal server. The default listening port of the portal server is
50100. However, if the listening port configured on the access device is not
50100, the destination port of the REQ_LOGOUT message is not the actual
listening port on the server. Thus, the portal server cannot receive the
REQ_LOGOUT message. As a result, you cannot force the user to log out the
portal server.
When the user uses the disconnect attribute on the client to log out, the portal
server actively sends a REQ_LOGOUT message to the access device. The source
port is 50100 and the destination port of the ACK_LOGOUT message from the
access device is the source port of the REQ_LOGOUT message so that the portal
server can receive the ACK_LOGOUT message correctly, no matter whether the
listening port is configured on the access device. Therefore, the user can log out
the portal server.
Solution
Use the display portal server command to display the listening port of the portal
server on the access device and use the portal server command in the system
view to modify it to ensure that it is the actual listening port of the portal server.