25.03.b.20250306.0140 - if_pppoe kernel module chap failure
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Decided to give the if_pppoe kernel module a go.
After the mandatory reboot no PPPoE connection.
Logs only have:if_pppoe: pppoe0: chap failure
Everything worked fine with mpd5.
Nothing odd about the connection that I can think of. Normal FTTP in the UK from an ISP using BT Wholesale's infrastructure.
The username is 27 characters long and as both a - and @ in it. That's typical for this type of ISP as the bit after the @ ends the authentication to the correct ISP.Is there a way I can capture the negotiation in more detail to see what's failing?
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@femtosize tcpdump should let you capture the PPP connection negotiation.
tcpdump -n -i <ethernet interface> -s0 -w /tmp/ppp.pcapshould produce a useful capture file in /tmp/ppp.pcap. -
@kprovost Thanks. That's let me see what's going on.
It appears the MD5 calculation is wrong as I get a failure packet back with the Message field set to "The password supplied was incorrect".
The challenge is 51 bytes long and the secret 9, along with the the id byte that's 61 bytes = 418 bits.
That means 59 bytes of padding will be required.I wonder if the 51 byte challenge is breaking things as most implementations I can find info on seem to use 16 bytes or maybe 24.
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@femtosize There's nothing obvious in the code. I'd expect long challenges to just work.
Can you share this capture to https://nc.netgate.com/nextcloud/s/Am58nWPJSZyf9JJ? Perhaps there's still something else to see in it.
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@kprovost OK. I've uploaded the capture.
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Thanks, we are checking...
