HSTS: Definition, Syntax, and Examples
HSTS (HTTP Strict Transport Security) is a header that forces the browser to always use HTTPS for a domain, even if the user types http:// or clicks an old http link. Configured with one line: Strict-Transport-Security: max-age=31536000; includeSubDomains; preload. Protects against downgrade attacks.
What is a HSTS
HSTS (HTTP Strict Transport Security) is a header that forces the browser to always use HTTPS for a domain, even if the user types http:// or clicks an old http link. Configured with one line: Strict-Transport-Security: max-age=31536000; includeSubDomains; preload. Protects against downgrade attacks.
Check HSTS online
Use the Enterno.io tool — enter a domain, get results in 1-2 seconds. Free, no signup.
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What Does the Security Analysis Check?
The tool checks HTTP security headers, SSL/TLS configuration, server info leaks, and protection against common attacks (XSS, clickjacking, MIME sniffing). A grade fromA to F shows overall security level.
Header Analysis
Checking Content-Security-Policy, HSTS, X-Frame-Options, X-Content-Type-Options, Referrer-Policy, and more.
SSL Check
TLS version, certificate expiry, chain of trust, HSTS support.
Leak Detection
Finding exposed server versions, debug modes, open configs, and directories.
Report with Recommendations
Detailed report explaining each issue with specific steps to fix it.
Who uses this
Security teams
HTTP header audit
DevOps
config verification
Developers
CSP & HSTS setup
Auditors
compliance checks
Common Mistakes
Strict-Transport-Security.Server: Apache/2.4.52 helps attackers find exploits. Hide the version.DENY or SAMEORIGIN.nosniff, browsers may misinterpret file types (MIME sniffing).Best Practices
Content-Security-Policy-Report-Only, monitor violations, then enforce.Server, X-Powered-By, X-AspNet-Version from responses.Get more with a free account
Security check history and HTTP security header monitoring.
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How-to
Frequently Asked Questions
How does HSTS differ from similar concepts?
See the full breakdown in the article above. For a quick check, use our online tool.
Does this need manual updates?
Usually no — most modern services configure it automatically. Manual setup is only needed for migrations or exotic configurations.