Stunnel

Stunnel is a versatile SSL encryption wrapper that seamlessly adds SSL/TLS security to various inetd daemons and standalone servers. It supports protocols like POP3, IMAP, SMTP, HTTP, and NNTP, enabling encrypted communications without modifying existing software. Built on the robust OpenSSL library, it inherits support for all compiled cryptographic algorithms. The tool is cross-platform and includes FIPS 140-2 validated encryption in its Windows installer, ensuring compliance and strong security for network services.