stunnel is an open-source multi-platform application used to provide a universal TLS/SSL tunneling service.
stunnel can be used to provide secure encrypted connections for clients or servers that do not speak TLS or SSL natively. It runs on a variety of operating systems, including most Unix-like operating systems and Windows. stunnel relies on the OpenSSL library to implement the underlying TLS or SSL protocol.
stunnel uses public-key cryptography with X.509 digital certificates to secure the SSL connection, and clients can optionally be authenticated via a certificate.
If linked against libwrap, it can be configured to act as a proxy-firewall service as well.
stunnel is maintained by Michał Trojnara and released under the terms of the GNU General Public License (GPL) with OpenSSL exception.
The packages for RHEL 8 and RHEL 7 are in each distribution’s respective Extra Packages for Enterprise Linux (EPEL) repository. The instructions for adding this repository diverge slightly between RHEL 8 and RHEL 7, which is why they’re listed separately below.
The EPEL repository can be added to RHEL 8 with the following command: