Generate a Secure TLS Configuration Without the Guesswork

Writing a TLS configuration from scratch is an exercise in copying fragments from documentation, forum answers and old blog posts, each written for a different server version and a different threat landscape. The result is often a configuration that works but nobody fully understands, which makes it hard to change and easy to break. A generator fixes the starting point: it produces a coherent, current configuration for your server type, with protocol versions, cipher suites and supporting settings chosen to work together. Your job then becomes reviewing and testing that configuration, rather than assembling it from fragments.

The TLS Configuration Generator produces a server configuration snippet from the options you choose, such as server software, desired compatibility level, and whether old clients must still be supported. It generates text for you to review and apply; it does not connect to your server or change anything itself. Review every generated setting before applying it, test it on staging, and never paste secrets, private keys or certificate material into the generator. A configuration snippet contains algorithm names and policy choices, not credentials, and it should stay that way.

Start by choosing the compatibility level honestly. A modern profile enables only TLS 1.2 and TLS 1.3 with strong suites, and suits most public websites today, because current browsers and mobile systems all support them. An intermediate profile adds a small number of older options for compatibility with older clients, and suits services that must serve a known older audience, such as a business application with a long-lived mobile app. An old profile, supporting obsolete protocols, should be reserved for exceptional cases where a specific legacy system cannot be upgraded, and it should carry an expiry date and a plan to retire it. Choosing a stricter profile than your audience needs creates support calls; choosing a looser one than you need creates exposure. Measure your audience before deciding, not after.

The settings that matter most

Protocol versions are the first setting. Enable TLS 1.3 and TLS 1.2, and disable SSL and all TLS versions below 1.2. This single choice removes whole classes of historical attacks, because the obsolete protocols are where most of the famous TLS vulnerabilities live. If a legacy client genuinely requires an older protocol, isolate it behind a separate endpoint with restricted access rather than weakening the main service for everyone. That separation is more work once, and safer every day afterwards.

Cipher suites come next, and the generator orders them with the strongest first. Prefer suites with ephemeral key exchange for forward secrecy and authenticated encryption such as AES-GCM or ChaCha20-Poly1305. Enable server cipher preference so your ordering governs the negotiation, rather than letting each client choose its own favourite. The generator's ordering reflects current guidance, but guidance changes, so note the date you generated the configuration and schedule a review. A configuration generated two years ago and never revisited is a configuration drifting out of date.

Supporting settings complete the picture. HTTP Strict Transport Security tells browsers to use HTTPS for your domain for a set period, which prevents downgrade tricks; set it only after confirming that HTTPS works everywhere on the site, because a long policy on a half-ready site can lock visitors out of plain-HTTP pages they still need. Session resumption settings affect both performance and security, and the generator's defaults are a reasonable starting point. OCSP stapling lets the server provide certificate revocation status itself, avoiding a slow extra lookup by the client, and it is worth enabling where your server supports it. Each of these settings is small alone; together they define whether the connection is merely encrypted or properly hardened.

Worked example: a small site moves to a modern profile

Suppose a small business website runs on a common web server with a configuration copied years ago: it enables TLS 1.0, 1.1 and 1.2, offers a long cipher list in no particular order, and has no strict transport security. The owner generates a modern profile for the server type, which enables only TLS 1.2 and 1.3, lists strong suites in server-preference order, and includes a strict transport security header with a modest initial duration. She reviews the generated snippet line by line, compares it with the old configuration, and notes two differences to check: the removal of TLS 1.0 and 1.1, and the removal of several older suites.

She applies the configuration to a staging copy of the site first and tests with current browsers on desktop and mobile, plus the business's own older office computer. All tests pass, and analytics show that no meaningful visitor traffic used the removed protocols in the past month. She then applies the change to production during a quiet period, monitors error rates for a week, and raises the strict transport security duration only after confirming that HTTPS works on every page, including subdomains served by the same certificate. The site's security posture improves in one change, and because the change was staged and monitored, the team knows it broke nothing rather than merely hoping so.

The staged approach is the transferable lesson. Generated configurations are starting points, not finished products: they need review against your server version, testing against your real clients, and monitoring after deployment. A generator removes the drudgery of assembling settings; it does not remove the responsibility of owning them.

Common mistakes

The most common mistake is generating a configuration for the wrong server or version and applying it without checking. Syntax and directive names differ between servers and versions, so a snippet for one server may fail or, worse, be silently ignored in part by another. Always confirm the target server and version, and check the server's error log after applying a change: a configuration that fails to load often leaves the old settings running, which looks like success until someone checks.

A second mistake is applying strict transport security too aggressively at first. A long duration on a site with mixed content or an HTTP-only subdomain can break parts of the site for months, because browsers remember the policy. Start with a short duration, verify thoroughly, and lengthen it gradually. A third mistake is forgetting certificate renewal in the excitement of a new configuration: a perfectly hardened server with an expired certificate serves nobody, so keep renewal automated and monitored regardless of how good the configuration is.

Also remember that a generated configuration is only as current as its guidance. If the generator's recommendations predate a major protocol change, cross-check them against current guidance from your server vendor or a reputable configuration guide before applying. The SSL/TLS Configuration Checker is a good second opinion: generate, apply to staging, then check the staged configuration and compare the findings with what you expected. The Security DNS Checker covers the DNS-side protections that complement TLS, such as email authentication records. For reading a full configuration report, see TLS Configuration, Read Properly.

FAQs

Will a modern profile break older visitors? For the overwhelming majority of visitors, no: current browsers, phones and operating systems support TLS 1.2 and 1.3. The risk concentrates in very old apps and devices, so check your traffic and test those clients explicitly before deciding.

Do I need to regenerate the configuration regularly? Review it at least annually and after major server upgrades or security announcements. Regenerating gives you current guidance; diffing the new output against your live configuration shows exactly what has changed.

Is a generator a substitute for a security audit? No. A generator produces a good baseline configuration, but it cannot see your certificates, your application code, or your network design. Treat it as the starting point of hardening, not the whole job.