↓ 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)


You can download testssl.sh by cloning this git repository:

git clone &mdash;depth 1 <a href="https://github.com/drwetter/testssl.sh.git" class='spip_url spip_out auto' rel='nofollow external'><span class="base64" title="aHR0cHM6Ly9naXRodWIuY29tL2Ryd2V0dGVyL3Rlc3Rzc2wuc2guZ2l0"></span></a>

Or help yourself downloading the ZIP archive https://github.com/drwetter/testssl.sh/archive/2.9dev.zip. Then testssl.sh --help will give you some help upfront. More help: see doc directory. Older sample runs are at https://testssl.sh/.


Here in the 2.9dev branch you find the development version of the software -- with new features and maybe some bugs — albeit we try our best before committing to test changes. For the previous stable version please see testssl.sh or download 2.8 from here. This project also release an interim release 2.9.5 which is is the successor of 2.8 and stable enough for day-to-day work.


testssl.sh is working on every Linux/BSD distribution out of the box. In 2.9dev most of the limitations of disabled features from the openssl client are gone due to bash-socket-based checks. As a result you can also use e.g. LibreSSL. testssl.sh also works on otherunixoid system out of the box, supposed they have /bin/bash and standard tools like sed and awk installed. System V needs to have GNU grep installed. MacOS X and Windows (using MSYS2 or cygwin) work too. OpenSSL version version >= 1.0.2 is recommended for better LOGJAM checks and to display bit strengths for key exchanges.

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

Features implemented in Readme.md#devel

  • Using bash sockets where ever possible —> better detection of ciphers, independent on the openssl version used.
  • Testing 359 default ciphers (testssl.sh -e/-E) with a mixture of sockets and openssl. Same speed as with openssl only but additional ciphers such as post-quantum ciphers, new CHAHA20/POLY1305, CamelliaGCM etc.
  • Further tests via TLS sockets and improvements (handshake parsing, completeness, robustness), TLS 1.2 protocol check via socket in production
  • Finding more TLS extensions via sockets
  • TLS Supported Groups Registry (RFC 7919), key shares extension
  • Non-flat JSON support
  • File output (CSV, JSON flat, JSON non-flat) supports a minimum severity level (only above supplied level there will be output)
  • Support of supplying timeout value for openssl connect — useful for batch/mass scanning
  • Parallel mass testing (!)
  • File input for serial or parallel mass testing can be also in nmap grep(p)able (-oG) format
  • Native HTML support instead going through ’aha’
  • Better formatting of output (indentation)
  • Choice showing the RFC naming scheme only
  • LUCKY13 and SWEET32 checks
  • Ticketbleed check
  • LOGJAM: now checking also for known DH parameters
  • Check for CAA RR
  • Check for OCSP must staple
  • Check for Certificate Transparency
  • Check for session resumption (Ticket, ID)
  • TLS Robustness check (GREASE)
  • Postgres und MySQL STARTTLS support, MongoDB support
  • Decodes BIG IP F5 Cookie
  • Better OpenBSD, better LibreSSL support
  • Man page

Further features planned in 2.9dev



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 a 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. Will Hunt provides a good https://www.4armed.com/blog/doing-your-own-ssl-tls-testing/ for version 2.8, including useful background info.

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

Cool web frontend

Mass scanner w parallel scans and elastic searching the results

Ready-to-go docker images are available at:

Brew package

Tools Cryptography