In the eighth installment of the Nginx Advanced series, we explore mutual TLS (mTLS) as a robust mechanism for identity verification at the transport layer. Unlike traditional password-based authentication, mTLS uses certificates to authenticate both the client and server, eliminating the risks of password theft and phishing.
The video, presented by Dargslan, breaks down the mTLS handshake and contrasts it with standard TLS. While standard TLS only verifies the server's identity, mTLS requires the client to present its own certificate, which the server validates against a trusted Certificate Authority (CA).
Key Topics Covered
- Why mTLS over passwords: mTLS provides stronger, certificate-based authentication that is resistant to credential theft.
- The handshake compared: The mTLS handshake adds an extra step: after the server sends its certificate, it requests the client's certificate and verifies it.
- Nginx configuration: Enabling mTLS requires just three directives:
ssl_client_certificate,ssl_verify_client, andssl_verify_depth. - OpenSSL setup: The tutorial demonstrates how to generate a CA, server, and client certificates using OpenSSL.
- Passing identity to backend: Nginx can forward certificate information (e.g.,
$ssl_client_s_dn) to backend applications via headers. - Revocation strategies: Methods like CRL and OCSP are discussed for revoking compromised certificates.
Practical Configuration Example
To configure mTLS in Nginx, add these lines to your server block:
ssl_client_certificate /etc/nginx/ca.crt;
ssl_verify_client on;
ssl_verify_depth 2;
proxy_set_header X-Client-Cert-Subject $ssl_client_s_dn;
This setup ensures that only clients with a valid certificate from your CA can access the server, and their identity is passed to the backend application.
The video is part of a 13-lesson course on Nginx advanced topics, available on the Dargslan channel. For more resources, visit dargslan.com.