An SSL checker (Secure Sockets Layer checker) is a tool that verifies proper installation of an SSL certificate on a Web server.
Multiple SSL certificate vendors offer Web-based tools to check the validity of an SSL certificate for a particular domain. An SSL checker is a useful tool for ensuring an SSL certificate is valid, trusted and will work properly for its users. It can also be used to set up expiration reminders to prevent an organization from missing certificate renewal dates.
Enterprise application, network and security teams often use SSL checkers as diagnostic tools to troubleshoot and fix issues that commonly occur during SSL certificate installation. To use an SSL checker, an enterprise can visit the website of any number of SSL certificate vendors and enter the URL of the enterprise domain into the SSL checker tool. In return, the SSL checker will provide information about the certificate, including:
- Common name
- Alternative names
- Server type
- Trustworthiness (including which Web browsers trust it)
- Serial number
- SHA1 thumbprint
- Fingerprint MD5
- Key length
- Signature algorithm
- Secure re-negotiation support
- If it uses a vulnerable Debian key
- Expiration date