Testing TLS/SSL encryption anywhere on any port
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drwetter Simplify run_logjam()
Looking @ pending #1114 two improvements were done:

1) Keep the status of DH group detected (<name> or "Unknown DH group")
   as well as the bit length
2) move the detection to a separate function get_common_prime()

There's still room for improvements when run_pfs() will take
over a part.

Also double code (my bad) from run_logjam() was move to a separate function.
Latest commit f18fb03 Oct 16, 2018



Build Status Gitter

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, OSX/Darwin, FreeBSD, NetBSD, OpenBSD (needs bash) and MSYS2/Cygwin out of the box: no need to install or to 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)


This software is free. You can use it under the terms of GPLv2, see LICENSE. In addition starting from version 3.0rc1 if you're offering it as a public and / or paid service you need to mention to your audience that you're using this program and where to get this program from.


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

git clone --depth 1 https://github.com/drwetter/testssl.sh.git

Or help yourself downloading the ZIP archive https://github.com/drwetter/testssl.sh/archive/2.9dev.zip. testssl.sh --help will give you some help upfront. More help: see doc directory with man pages. 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. Be aware that we also change the output or command line.

For the previous stable version please see testssl.sh or download the interim release 2.9.5 from here 2.9.5 which is is the successor of 2.8 and stable for day-to-day work.


testssl.sh is working on every Linux/BSD distribution out of the box. Since 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 other unixoid system out of the box, supposed they have /bin/bash >= version 3.2 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 @ twitter.

Features implemented in 2.9dev

  • Using bash sockets where ever possible --> better detection of ciphers, independent on the openssl version used.
  • Testing 364 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
  • Check for vulnerability to Bleichenbacher attacks
  • Ticketbleed check
  • Decoding of unencrypted BIG IP cookies
  • LOGJAM: now checking also for known DH parameters
  • Check for CAA RR
  • Check for OCSP must staple
  • Check for Certificate Transparency
  • Expect-CT Header Detection
  • Check for session resumption (Ticket, ID)
  • TLS Robustness check (GREASE)
  • Postgres und MySQL STARTTLS support, MongoDB support
  • Decodes BIG IP F5 Cookie
  • Fully OpenBSD and LibreSSL support
  • Missing SAN warning
  • Man page
  • Better error msg suppression (not fully installed OpenSSL)
  • DNS over Proxy and other proxy improvements
  • Better JSON output: renamed IDs and findings shorter/better parsable
  • JSON output now valid also for non-responsing servers
  • Added support for private CAs
  • Exit code now 0 for running without error
  • ROBOT check
  • Better extension support
  • Better OpenSSL 1.1.1 support
  • Supports latest and greatest version of TLS 1.3, shows drafts supported

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 coding guideline.

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 description 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

A ready-to-go docker image is at:

Privacy checker using testssl.sh

Brew package