TLS Renegotiation Checker

Check if server supports secure TLS renegotiation

About TLS Renegotiation

TLS renegotiation allows a client and server to renegotiate cryptographic parameters within an established TLS session. Secure renegotiation (RFC 5746) fixes a serious vulnerability where an attacker could inject their own traffic into a TLS session through a man-in-the-middle attack. Our checker tests whether your server supports secure renegotiation and whether it is vulnerable to insecure renegotiation attacks.

How to Use

Enter the domain name of the server you want to test.
Click "Check" to test the server's TLS renegotiation support.
Review the results showing secure renegotiation support, insecure renegotiation status, and RFC 5746 compliance.
If insecure renegotiation is detected, update your server configuration immediately.

Use Cases

•Verify that servers are patched against the TLS renegotiation MITM vulnerability
•Check RFC 5746 compliance for security audits and penetration tests
•Identify legacy servers that may still support insecure renegotiation
•Validate security configuration after server updates and patches

Frequently Asked Questions

TLS renegotiation is a mechanism that allows a client and server to renegotiate cryptographic parameters within an existing TLS session. It can be initiated by either party and is used for purposes like updating encryption keys or requesting client certificates mid-session.

Discovered in 2009, the TLS renegotiation vulnerability allowed an attacker to inject arbitrary data into a TLS session by performing a man-in-the-middle attack during renegotiation. RFC 5746 fixed this by adding cryptographically binding the renegotiation handshake to the original connection.

To fix insecure renegotiation, update your server software to the latest version. Most modern web servers (Apache, Nginx, IIS) have been patched since 2010. Ensure you are running a supported version with all security updates applied. For OpenSSL-based servers, version 0.9.8m or later includes the fix.

Tips & Best Practices

•Configure TLS renegotiation securely to prevent renegotiation attacks
•Use secure renegotiation (RFC 5746) for all TLS connections
•Monitor renegotiation usage for security awareness
•Disable renegotiation if not required for your application

Technical Details

Protocol: TLS renegotiation support and security analysis
Secure: RFC 5746 secure renegotiation implementation
Risk: Renegotiation attack vulnerability assessment
Output: Renegotiation support status with security recommendations