Integrations/VPN/openvpn
Access Server · Community · RADIUS

MFA for OpenVPN

OpenVPN — whether Access Server or a community build — secures remote access for teams of every size, and its logins are only as strong as the passwords behind them. Both editions can authenticate against RADIUS, and the community server can use a PAM module, but neither ships MFA on its own. Authnull provides the factor over either path. You enable RADIUS authentication, point it at Authnull, and a push or OTP challenge is required before the tunnel is allowed.

At a glance
VendorOpenVPN / Access Server
Connects viaRADIUS / PAM
ProtectsRemote-access VPN
DeploymentAgentless
Setup time20 minutes
No rip-and-replace — sits in front of your existing setup
How Authnull connects

OpenVPN forwards the login; Authnull adds the factor.

OpenVPN
user connects
Authnull
RADIUS / PAM
Directory
AD / LDAP
User device
approve factor

OpenVPN forwards the login to Authnull over RADIUS (or via PAM on the community server); Authnull validates the credential, challenges for the factor, and returns the result. Set the auth timeout high enough for push approval.

Setup

Configure MFA for OpenVPN

Real steps — the exact menus, fields, and values. Follow along in your console; the whole thing takes about 20 minutes.

1

Enable RADIUS authentication

In Access Server, switch the authentication method to RADIUS and add the Authnull connector with its shared secret.

Admin UI → Authentication → RADIUS
2

Point community builds at RADIUS via plugin

For the community server, load the RADIUS plugin and configure it to reach Authnull.

server.conf
plugin /usr/lib/openvpn/radiusplugin.so /etc/openvpn/radiusplugin.cnf
3

Set the server and secret

In the RADIUS plugin config, set the Authnull IP, ports, and shared secret.

radiusplugin.cnf
server {
  acctport=1813
  authport=1812
  name=10.0.0.20
  sharedsecret=<shared-secret>
}
4

Raise the timeout and test

Increase the connection auth timeout, then connect with the OpenVPN client and approve the factor to bring up the tunnel.

Reference — connection values
ProtocolRADIUS / PAM
auth port1812
acct port1813
Timeout60s

Closes the MFA gap auditors look for

Enforcing MFA on OpenVPN gives you evidence for the remote-access and privileged-access controls in SOC 2 and the access requirements under CCPA — with per-login logs you can hand straight to an assessor.

Add MFA to OpenVPN — free to start.

Spin up Authnull, point OpenVPN at it, and enforce a factor on a pilot group today. No card, no rip-and-replace.

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