The stunnel program is designed to work as an SSL encryption wrapper between remote client and local (inetd-startable) or remote server. It can be used to add SSL functionality to commonly used inetd daemons like POP2, POP3, and IMAP servers without any changes in the programs’ code.

Stunnel uses OpenSSL or SSLeay libraries for cryptography, so it supports whatever cryptographic algorithms you compiled into your library.

Stunnel is written by Michal Trojnara and distributed as a free software under the GNU GPL license.

More information on Stunnel is available from

Stunnel 5.58 – Updated 2021-06-16

Stunnel 5.50 – updated 20190113

Stunnel 5.41 – updated 20170516

Stunnel 5.09 – updated 20150105