wpa_supplicant fails to connect with EAP

Kenny Pearce kenny
Tue Aug 18 07:55:53 PDT 2015

Thanks! The MTU was set to 1280 (I don't know why). Changing it to 1500
fixed the problem.

On Tue, 18 Aug 2015 02:39:46 +0300
Jouni Malinen <j at w1.fi> wrote:

> On Mon, Aug 17, 2015 at 11:35:48AM -0500, Kenny Pearce wrote:
> > Aug 17 11:15:24 parmenides wpa_supplicant[1312]: wlan21:
> > CTRL-EVENT-EAP-METHOD EAP vendor 0 method 13 (TLS) selected Aug 17
> > 11:15:24 parmenides wpa_supplicant[1312]: l2_packet_send - sendto:
> > Message too long
> What MTU do you have configured on wlan21? E.g., check what "ifconfig
> wlan0" returns.
> > The only thing that looks like a significant error to me in this
> > output is "l2_packet_send - sendto: Message too long" but Googling
> > that message did not lead to any useful hits. Does anyone know what
> > might cause this kind of problem, or how to fix it?
> I have not seen this before, but my first guess would be that
> something has reduced the MTU on the netdev so much that the default
> EAP-TLS fragmentation limit gets hit. wpa_supplicant does not
> currently check the MTU and update the fragmentation limit
> automatically, but now that I learned about this, I'll probably make
> it do so. As a workaround, you can try to reduce EAP fragment size
> with fragment_size=<bytes> parameter (though, I do not know how to do
> that with NetworkManager). Setting fragment_size to something like
> 100 bytes less than netdev MTU would hopefully get rid of this issue
> (or alternatively, increase the MTU back to more common 1500 if there
> is no real need to make it smaller). 

Kenny Pearce
"Few men think, yet all will have opinions." - George Berkeley

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