L2TP VPN Active Directory authentication do not work

Sébastien · October 2022

Hi everyone,

I'm trying to set up an L2TP/IPSec VPN with AD authentication but it does not work because my user is rejected. The appliance is a USG Flex 100 managed by Nebula.

First of all, I add my AD to Nebula

Image: https://us.v-cdn.net/6029482/uploads/editor/jr/pk2zy0bh3cx2.png

And I configure the VPN server with my AD for authentication

Image: https://us.v-cdn.net/6029482/uploads/editor/l4/kzxllovbiuws.png

Then I add a test user to my AD users

Image: https://us.v-cdn.net/6029482/uploads/editor/io/9njqhzfgvitz.png

And finally, here is the log when trying to connect to this VPN

Image: https://us.v-cdn.net/6029482/uploads/editor/oy/rjdn1y58dn8s.png

It's really surprising because I'm 200% hundred sure of the username and password.

Am i doing something wrong ? Please also note that the USG Flex is correctly added to my AD in the "Computers" section.

Should I configure something else on my AD ? NPS maybe ? Or should the user be added to a specific group ?

Thanks,

Sebastien

Zyxel_James · October 2022

Hello @Sébastien,

Please confirm the account could be queried by your firewall. Connect to console port and input

"_debug domain-auth test profile-name example.profile.name username example.username password example.password".

Moreover, please provide org/site to me via private message, and enable Zyxel support access, you can find it at Help > Support Request > Zyxel support access, enable zyxel support. I would like to check on your device, thank you.

James

Sébastien · December 2022

Dear James,

I have tried the command using a SSH connection to the router, and the answer is :

% Get AD group VDC has failed

retval = -24004

ERROR: Display AAA group has failed.

Where VDC is the name of my AD configuration in Nebula.

What does this mean ?

Thanks,

Sébastien

Zyxel_James · December 2022

Hi @Sébastien, I have contacted you via PM, please check your inbox, thank you.

James

L2TP VPN Active Directory authentication do not work

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