FILS reassociation duplicate sequence number

Jouni Malinen j at
Wed Aug 25 02:37:06 PDT 2021

On Thu, Aug 05, 2021 at 08:01:04AM -0700, James Prestwood wrote:
> I am running into a problem where the radius server thinks there was a
> duplicate access request during FILS reassocation. I have two EAP/FILS
> enabled APs. Here is the sequence of events:
>  - Authenicate over EAP to AP1
>  - Disconnect from AP1 and authenticate using FILS to AP1
>  - Reassociate to AP2 using FILS
> Everything appears to be working fine initially (my identity is found)
> but then the radius server throws the message away claiming the
> sequence number is a duplicate:

Which station implementation are you using here and would you be able to
provide debug logs from both the authentication server and station for
all those authentication attempts?

> EAP: SEQ=0 replayed (already received SEQ=0)
> And sure enough, if I remove the sequence number check it all works as
> expected and I am able to reassociate:

Well, I don't think I'd call that "as expected" taken into account reuse
of the same sequence number is incorrect and a potential security

Jouni Malinen                                            PGP id EFC895FA

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