Stunnel

As a cross-platform SSL encryption wrapper, Stunnel enhances the security of inetd daemons and standalone servers including NNTP, SMTP, and HTTP by implementing SSL functionality. It relies on the OpenSSL library for cryptography, supporting various algorithms and benefiting from FIPS 140-2 validation where applicable. The latest Windows builds include the OpenSSL FIPS Provider, making it a reliable choice for organizations needing certified encryption without altering existing server code.