↓ download on github


testssl.sh is a free command line tool which checks a server’s service on any port for the support of TLS/SSL ciphers, protocols as well as some cryptographic flaws.

Key features

  • Clear output: you can tell easily whether anything is good or bad
  • Ease of installation: It works for Linux, Darwin, FreeBSD, NetBSD and MSYS2/Cygwin out of the box: no need to install or configure something, no gems, CPAN, pip or the like.
  • Flexibility: You can test any SSL/TLS enabled and STARTTLS service, not only webservers at port 443
  • Toolbox: Several command line options help you to run YOUR test and configure YOUR output
  • Reliability: features are tested thoroughly
  • Verbosity: If a particular check cannot be performed because of a missing capability on your client side, you’ll get a warning
  • Privacy: It’s only you who sees the result, not a third party
  • Freedom: It’s 100% open source. You can look at the code, see what’s going on and you can change it.
  • Heck, even the development is open (github)


Here in the master branch you find the stable version 2.8rc3 of the software, it superseds 2.6. Version 2.8 is currently being finalized . 2.9dev is the new developement branch For the a more thorough description of the command line options please see https://testssl.sh/ "Go to the site with the stable version and more documentation" or https://github.com/drwetter/testssl.sh/wiki/Usage-Documentation.


testssl.sh is working on every Linux/BSD distribution out of the box with some limitations of disabled features from the openssl client — some workarounds are done with bash-socket-based checks. It also works on other unixoid system out of the box, supposed they have /bin/bash and standard tools like sed and awk installed. MacOS X and Windows (using MSYS2 or cygwin) work too. OpenSSL version >= 1 is a must. OpenSSL version >= 1.0.2 is needed for better LOGJAM checks and to display bit strengths for key exchanges.

Features in Readme.md#stable

Done so far:

  • Trust chain check against certificate stores from Apple (OS), Linux (OS), Microsoft (OS), Mozilla (Firefox Browser), works for openssl >=1.0.1
  • IPv6 (status: 80% working, details see https://github.com/drwetter/testssl.sh/issues/11
  • works now on servers requiring a x509 certificate for authentication
  • extensive CN <—> hostname check
  • SSL Session ID check
  • Avahi/mDNS based name resolution
  • HTTP2/ALPN protocol check
  • Logging to a file / dir
  • Logging to (flat) JSON + CSV
  • HPKP checks now also for Root, intermediate SPKIs
  • Check for multiple server certificates
  • Browser cipher simulation: what client will connect with which cipher + protocol
  • GOST cipher+certificate improvements
  • Assistance for color-blind users
  • Even more compatibility improvements for FreeBSD, NetBSD, Gentoo, RH-ish, F5 and Cisco systems
  • Considerable speed improvements for each cipher runs (-e/-E)
  • More robust SSLv2 + TLS socket interface
  • seperate check for curves
  • OpenSSL 1.1.0 compliant
  • check for DROWN
  • Whole number of bugs squashed

Update notification here or @ https://twitter.com/drwetter.


Contributions, feedback, bug reports are welcome! For contributions please note: One patch per feature — bug fix/improvement. Please test your changes thouroughly as reliability is important for this project.

There’s https://github.com/drwetter/testssl.sh/wiki/Coding-Style.

Please file bug reports @ https://github.com/drwetter/testssl.sh/issues.


For a start see the wiki. Help is needed here.

Bug reports

Please file bugs in the issue tracker. Do not forget to provide detailed information, see https://github.com/drwetter/testssl.sh/wiki/Bug-reporting. (Nobody can read your thoughts -- yet. And only agencies your screen) ;-)

External/related projects

Please address questions not specifically to the code of testssl.sh to the respective projects

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