[RADIATOR] EAP Response type 25, but no expected type known - Rogue Access Point?

Heikki Vatiainen hvn at open.com.au
Wed Sep 4 09:52:50 UTC 2019

On 03/09/2019 23.03, Ullfig, Roberto Alfredo wrote:
> If a rogue access point existed and a user walks within range of both a 
> legitimate and rogue AP while authenticating - could the EAP packets be 
> distributed between the two systems possibly resulting in:
> EAP Response type 25, but no expected type known
> on the legitimate server?

Before going into possible reasons, I'll quickly summarise what this 
message means. This message is logged when a PEAP (type 25) message from 
a RADIUS client is received, but Radiator couldn't find a currently 
ongoing EAP authentication this response (message from client) belongs 
to. In short: unexpected PEAP message from client was received.

One reason this could happen is when a RADIUS client has multiple RADIUS 
servers configured and it decides for some reason to switch to another 
server. It might be that the client's retransmission and failover 
settings triggered a switch to another server when there was a problem 
in the network and messages were dropped. These problems then led the 
client to think its currently active RADIUS server was having problems.

I'd think that if the end user was communicating with a rogue AP first 
and then switching to a trusted AP, then the trusted AP would force the 
end user to start authentication from the scratch. This would mean 
sending EAP-Response/Identity, not continuing with EAP-Response/PEAP.

I would first check if there's a possibility that a non-rogue AP or 
controller was doing a switch to a different RADIUS server. If not, I'd 
then take a look at the possible other causes.


Heikki Vatiainen <hvn at open.com.au>

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