On Wed, 18 Oct 2017, Jeremy Utley via FreeIPA-users wrote:
In the process of changing to a FreeIPA based authentication system for a
part of our network. FreeIPA is set up, working beautifully for most
things already. Right now, we're trying to convert our old jump hosts from
C6+OpenLDAP+Vasco OTP devices to a new C7+FreeIPA+Yubikey setup. The way
this setup currently works is that the user creates a VPN connection to the
jump host (using OpenVPN and static VPN keys), logs into the jump via SSH
over the VPN tunnel with the Vasco OTP password, then can move from there
to other machines on the network with only password.
As part of the transition to the new setup, I wanted to change to having
OpenVPN authenticate against FreeIPA using the openvpn pam plugin. This
was working fine when using just passwords, OpenVPN prompted for the
Username and Password and connected, so the basic idea seems to work. But
as soon as I enabled the first user with the Yubikey 2FA, the OpenVPN
server will no longer authenticate him when using Password+Yubikey value.
However, that user can authenticate to the FreeIPA web interface
successfully with the Yubikey, as well as SSH to the machine running
Openvpn (tested by using the old setup and jumping to the new hosts).
As I understand it, using the OpenVPN PAM module should allow it to auth
just like SSH does, so I'm puzzled why this is failing as it does. I
created the OpenVPN PAM configuration file by copying /etc/pam.d/login to
/etc/pam.d/openvpn, as well as adding the new openvpn service to FreeIPA
and granting the user access to it (of course, as the user is allowed to
connect when OTP is not enabled).
Has anyone done a similar setup before, and have any ideas where I went
wrong? I'd like to have this working for added security on our VPN
OpenVPN's pam authentication plugin does not properly implement support
for multiple prompts which pam_sss produces in case of 2FA. It only
supports single password request. See code in
SSSD has support for for such behavior in sshd but the service name is
There are tickets to track the latter part in SSSD:
https://pagure.io/SSSD/sssd/issue/3264. Patches are welcome.
As to openvpn itself, there is a little problem that afaik openvpn
doesn't have a mechanism to negotiate multiple prompts with its client.
/ Alexander Bokovoy
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