It’s a good option if you can’t do anything better, like a VPN. Because there is always the risk of an authentication bypass vulnerability. The less attack surface, the better.

I use mTLS with Caddy to expose some of my services. It is quite manageable, and I only use if for myself and my wife.

We both use Android phones, and I configure access via apps for the services, that use the devices’ certificate store. It seems like the iOS way is to provide the client certificate and password to each app that’s gonna use it. I’m happy we can avoid that.

Big plus side for us is the simplicity of it all, there is no “always on VPN” requirement, and things “just work” with acceptable security.

I also sometimes access the services via Firefox, which is also able to use the device’s certificate store, although I have to keep selecting the same certificate each time.

MTLS is great protection, but the use case must support it. For example, if you want your app to support registration for new accounts or if you have a lot of people you want to have access, that might make mTLS unwieldy to manage.

I host apps behind Traefik reverse proxy, using the d.rymcg.tech framework. It make it easy to protect your apps behind HTTP basic auth, Oauth2, or mTLS(or any combination).

I use Tailscale for this, with my own Headscale server so that I am in control of everything. It’s a much easier approach that is more likely to pass the spousal acceptance factor.

I am using mTLS implemented by nginx to access my services like Home Assistant, Paperless, Tandoor, Immich and so on. Clients are Windows, Linux and Android based so no iOS experience. Adding new clients can be tricky if you need to figure out how to provide the certificate first. Once it works, it’s rock solid

@observantTrapezium

mTLS can be a very good extra gate for a small, controlled device set. But “some services”, “smartphones” and “Apache reverse proxy” is not enough to recommend it responsibly.

The decisive questions are:

• Which services are we talking about: a normal web UI in a mobile browser, native apps, APIs, WebDAV, SSH-like administration, something else?
• Are those personally managed devices, or devices belonging to multiple users?
• iOS, Android, both — and which browsers/apps?
• Is there MDM, or would certificate enrollment, replacement, revocation and renewal all be manual?
• What happens when a phone is lost, reset, sold, or its private key leaks?
• Does each device get its own certificate, or would the same .p12 be copied around? (Please do not do the latter.)
• Is the real goal “no public login page”, “device authentication”, or simply private remote access?

For a handful of your own devices, per-device mTLS certificates can be perfectly reasonable. For a mixed fleet of smartphones without MDM, the operational overhead is often the actual attack surface: secure initial delivery of the PKCS#12 bundle, private-key protection, expiration, rotation, revocation, backups, and users selecting the right certificate.

Also: mTLS is a gate, not a replacement for normal authentication and authorization. I would usually still keep the application login, use individual device certificates with a private CA, short-ish validity, documented revocation, and rate limits. Otherwise you have merely replaced password brute force with “whoever extracted or copied the client private key gets through.”

Depending on the service, a WireGuard/Tailscale-style private network or an identity-aware proxy may be less painful on phones — but that is impossible to judge without knowing the actual services and client workflow. Certificate-based mobile access is feasible, yet the setup and lifecycle vary materially across platforms and applications.

So yes: the missing basics are not a minor omission; they are the question.