testssl icon

Testing TLS/SSL encryption


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 recent cryptographic flaws and more.

NameLast ModifiedSizeType
2.6/2018-Nov-15 22:01:54-- Directory
2.8/2018-Nov-15 22:46:12-- Directory
2.9.5/2025-Apr-23 11:58:47-- Directory
3.0/2025-Jun-15 10:57:44-- Directory
3.2/2025-Jun-14 12:46:37-- Directory
bleichenbacher/2018-Feb-23 18:00:33-- Directory
contributed_binaries/2025-Apr-01 12:29:08-- Directory
doc/2025-Jun-14 12:46:53-- Directory
etc/2025-Jun-14 12:47:08-- Directory
utils/2025-Apr-23 12:13:12-- Directory
CHANGELOG.md2025-Apr-23 11:33:3921.16KB MD File
CONTRIBUTING.md2025-Apr-23 11:33:391.91KB MD File
CREDITS.md2025-Apr-23 11:33:395.23KB MD File
Coding_Convention.md2025-Apr-23 11:33:395.66KB MD File
Dockerfile2025-Apr-23 11:33:391.91KB Unknown File
Dockerfile.git2025-Apr-23 11:33:39682.00B GIT File
Dockerfile.md2025-Apr-23 11:33:391.51KB MD File
LICENSE2025-Apr-23 11:33:3917.67KB Unknown File
Readme.md2025-Apr-23 11:33:398.48KB MD File
openssl-iana.mapping.html2025-Apr-23 11:33:3961.11KB HTML File
robots.txt2025-Oct-07 23:44:26466.00B TXT Type Document
testssl-readme.txt2025-May-29 11:40:57404.00B TXT Type Document
testssl.sh2026-Jun-19 14:22:021.21MB SH File
testssl.sh-3.0.10.tar.gz2025-Jun-15 10:54:109.04MB GZ Compressed Archive
testssl.sh-3.0.10.tar.gz.asc2025-Jun-15 10:54:10833.00B ASC File
testssl.sh-3.2.0.tar.gz2025-Apr-23 11:53:246.65MB GZ Compressed Archive
testssl.sh-3.2.0.tar.gz.asc2025-Apr-23 11:53:22488.00B ASC File
testssl.sh-3.2.1.tar.gz2025-Jun-13 14:38:426.66MB GZ Compressed Archive
testssl.sh-3.2.1.tar.gz.asc2025-Jun-13 14:38:42833.00B ASC File
testssl.sh-3.2.2.tar.gz2025-Oct-28 22:14:036.66MB GZ Compressed Archive
testssl.sh-3.2.2.tar.gz.asc2025-Oct-28 22:17:55508.00B ASC File
testssl.sh-3.2.3.tar.gz2026-Mar-01 14:49:596.67MB GZ Compressed Archive
testssl.sh-3.2.3.tar.gz.asc2026-Mar-01 14:52:55508.00B ASC File
testssl.sh-3.3dev-snapshot-2602.tar.gz2026-Mar-01 14:49:426.68MB GZ Compressed Archive
testssl.sh-3.3dev-snapshot-2602.tar.gz.asc2026-Mar-01 14:53:19508.00B ASC File
testssl_german_owasp_day.pdf2018-Nov-18 13:53:381.11MB PDF Type Document

Key features

License

testssl.sh is free and open source software. You can use it under the terms of GPLv2, please review the License before using it.

Attribution is important for the future of this project -- also in the internet. Thus if you're offering a scanner based on testssl.sh as a public and/or paid service in the internet you are strongly encouraged to mention to your audience that you're using this program and where to get this program from. That helps us to get bugfixes, other feedback and more contributions.

Donations

If you like this software, you or your company uses it a lot or even your company makes money from any service around testssl.sh, why show your appreciation and not support the project with a donation? It helps keeping the project alive and kicking. Appreciation motivates the developer.

Dirk setup a paypal account for it, keeps track of the money and makes sure it is spend on project related activities.

Donate with PayPal


If you want a deductable commercial invoice in return please get in touch with me before using paypal.

Development

github Development takes place at github. We're now @ 3.2.3 (stable) and 3.3dev.
There was a last release of 3.0.10 (oldstable) but that was the last one in the 3.0.x branch.



Support status

Supported will always be the current dev version and the version before (n-1 rule). As soon as the dev version becomes the stable release, this will be the n-1 version and receives bugfixes only. The dev version has historically not delivered really broken software (no facebook paradigm). Consider it like a rolling release: It'll definitely change-- that is the point of development-- things might break for you if you e.g. expect the output or features all to be the same. But other than that: The dev version itself won't break (TM).

We are focussing on 3.3dev, further development will take place in this branch. We aim to not break things badly but, as said, things will change. If you want to make use of new features like QUIC, TLS 1.3 0-RTT, newer SSLlabs rating, check for the Opossum vulnerability and more, you should consider this branch. We have one snapshot so far, see below. Worth noticing: 3.2 included 6 KEMs already, ML-DSA but will not receive any new features. 3.2 is the stable branch. There was one final 3.0.10 release. If you need longer support for 3.0.x there's a possibility for paid maintenance support.

-

February 13, 2026: Prerelease/snapshot of 3.3dev, see github or here (signature) .

February 12, 2026: Release of bugfixed version 3.2.3, see 3.2.3 github or here (signature) .

September 18, 2025: Release of bugfixed version 3.2.2, see 3.2.2 github or here (signature) .

June 15, 2025: Start of new development branch 3.3dev, see 3.3dev github.

June 15,2025: Release of final bugfixed version 3.0.10, see 3.0.10 github or here (signature) .

June 13, 2025: Release of bugfixed version 3.2.1, see 3.2.1 @ github or here (signature) .

April 23, 2025: Release of final stable version 3.2.0, after several release candidates. see 3.2.0 @ github or here (signature) .

Jun 13, 2024: Version 3.0.9, see 3.0.9 @ github or here(signature) .

Oct 10, 2023: After several non-tagged and not labelled rc versions a now version 3.2rc3 was released, see 3.2rc3 @ github

Sep 19, 2022: Version 3.0.8, see 3.0.8 @ github or here(signature) .

Feb 19, 2022: Version 3.0.7, see 3.0.7 @ github or here(signature) .
[..]
Jan 23, 2020: Version 3.0 release, see 3.0 @ github. It's been a long rolling release candidate phase since the first 3.0 RC version.

Dec 12, 2017: ROBOT / Bleichenbacher check has been implemented. . Read more about this old+new attack @ robotattack.org. Please checkout 2.9dev @ github. I compiled also some info here, including an Alexa Top 10k scan and some background information.

Sep 19, 2017: Version 2.9.5 has been released. Please checkout 2.9.5 @ github or download it from here, you need the etc tar ball as well.

Longer read

testssl.sh is pretty much portable/compatible. It is working on every Linux, Mac OS X, FreeBSD distribution, on MSYS2/Cygwin (slow). It is supposed also to work on any other unixoid systems. A newer OpenSSL version (1.0) is recommended though. /bin/bash is a prerequisite – otherwise there would be no sockets.

Speaking of it: Since version 2.4 some of the checks were done with bash sockets. This improved gradually and from 2.9.5 on almost every check is done with bash sockets. Still OpenSSL is needed for some core functions like openssl <verify|ocsp|pkey> . In principle any OpenSSL or even LibreSSL can be used as a helper. It's recommended to use the one supplied as it makes sure special tests or features like IPv6, proxy support, STARTTLS MySQL or PostgreSQL are supported. (The one supplied stems originally from github.com/PeterMosmans/openssl. openssl-1.0.2k-chacha.pm.ipv6.Linux+FreeBSD.tar.gz is a Linux- and FreeBSD-only tarball. The directory openssl-1.0.2i-chacha.pm.ipv6.contributed/ contains contributed builds for ARM7l and Darwin binaries).

Download shortcuts

Note the following features are supported by the webserver configuration: – each to standard output. Please note however that from 2.9dev on you need the mandatory files in etc/ though, see https://github.com/testssl/testssl.sh/tree/3.0/etc.

Usage

The normal use case is probably just testssl.sh <hostname>, see first picture right hand above (a deliberately bad configuration).

Starting testssl.sh with no params will give you a general idea how to use it: 
userid@somehost:~ % testssl.sh

     "testssl.sh [options] <URI>"    or    "testssl.sh <options>"

"testssl.sh <option>", where <option> is mostly standalone and one of:

     --help                        what you're looking at
     -b, --banner                  displays banner + version of testssl.sh
     -v, --version                 same as previous
     -V, --local [pattern]         pretty print all local ciphers (of openssl only). If search pattern supplied: it is an
                                   an ignore case word pattern of cipher hexcode or any other string in its name, kx or bits

"testssl.sh [options] <URI>", where <URI> is:

     <URI>                         host|host:port|URL|URL:port   port 443 is default, URL can only contain HTTPS as a protocol

  and [options] is/are:

     -t, --starttls <protocol>     Does a run against a STARTTLS enabled service which is one of ftp, smtp, lmtp, pop3, imap,
                                   xmpp, xmpp-server, telnet, ldap, nntp, sieve, postgres, mysql
     --xmpphost <to_domain>        For STARTTLS xmpp or xmpp-server checks it supplies the domainname (like SNI)
     --mx <domain/host>            Tests MX records from high to low priority (STARTTLS, port 25)
     --file/-iL <fname>            Mass testing option: Reads one testssl.sh command line per line from <fname>.
                                   Can be combined with --serial or --parallel. Implicitly turns on "--warnings batch".
                                   Text format 1: Comments via # allowed, EOF signals end of <fname>
                                   Text format 2: nmap output in greppable format (-oG), 1 port per line allowed
     --mode <serial|parallel>      Mass testing to be done serial (default) or parallel (--parallel is shortcut for the latter)
     --warnings <batch|off>        "batch" doesn't continue when a testing error is encountered, off continues and skips warnings
     --socket-timeout <seconds>    useful to avoid hangers. Max <seconds> to wait for the TCP connect to get ACKed
     --openssl-timeout <seconds>   useful to avoid hangers. Max <seconds> to wait before openssl connect will be terminated

single check as <options>  ("testssl.sh URI" does everything except -E and -g):
     -e, --each-cipher             checks each local cipher remotely
     -E, --cipher-per-proto        checks those per protocol
     -s, --std, --categories       tests standard cipher categories by strength
     -f, --fs, --forward-secrecy   checks forward secrecy settings
     -p, --protocols               checks TLS/SSL protocols, for HTTP: including QUIC/HTTP/3 and ALPN/HTTP2 (and SPDY)
     -g, --grease                  tests several server implementation bugs like GREASE and size limitations
     -S, --server-defaults         displays the server's default picks and certificate info
     -P, --server-preference       displays the server's picks: protocol+cipher
     -x, --single-cipher <pattern> tests matched <pattern> of ciphers
                                   (if <pattern> not a number: word match)
     -c, --client-simulation       test client simulations, see which client negotiates with cipher and protocol
     -h, --header, --headers       tests HSTS, HPKP, server/app banner, security headers, cookie, reverse proxy, IPv4 address

     -U, --vulnerable              tests all (of the following) vulnerabilities (if applicable)
     -H, --heartbleed              tests for Heartbleed vulnerability
     -I, --ccs, --ccs-injection    tests for CCS injection vulnerability
     -T, --ticketbleed             tests for Ticketbleed vulnerability in BigIP loadbalancers
     --OP, --opossum               tests for Opossum vulnerability
     --BB, --robot                 tests for Return of Bleichenbacher's Oracle Threat (ROBOT) vulnerability
     --SI, --starttls-injection    tests for STARTTLS injection issues
     -R, --renegotiation           tests for renegotiation vulnerabilities
     -C, --compression, --crime    tests for CRIME vulnerability (TLS compression issue)
     -B, --breach                  tests for BREACH vulnerability (HTTP compression issue)
     -O, --poodle                  tests for POODLE (SSL) vulnerability
     -Z, --tls-fallback            checks TLS_FALLBACK_SCSV mitigation
     -W, --sweet32                 tests 64 bit block ciphers (3DES, RC2 and IDEA): SWEET32 vulnerability
     -A, --beast                   tests for BEAST vulnerability
     -L, --lucky13                 tests for LUCKY13
     -WS, --winshock               tests for winshock vulnerability
     -F, --freak                   tests for FREAK vulnerability
     -J, --logjam                  tests for LOGJAM vulnerability
     -D, --drown                   tests for DROWN vulnerability
     --rc4, --appelbaum            which RC4 ciphers are being offered?

tuning / connect options (most also can be preset via environment variables):
     -9, --full                    includes tests for implementation bugs and cipher per protocol (could disappear)
     --bugs                        enables the "-bugs" option of s_client, needed e.g. for some buggy F5s
     --assume-http                 if protocol check fails it assumes HTTP protocol and enforces HTTP checks
     --ssl-native                  use OpenSSL where sockets are normally used. Faster but inaccurate, avoid it if possible
     --openssl <PATH>              use this openssl binary (default: look in $PATH, $RUN_DIR of testssl.sh)
     --proxy <host:port|auto>      (experimental) proxy connects via <host:port>, auto: values from $env ($http(s)_proxy)
     -4                            Scan IPv4 only
     -6                            Scan IPv6 only. Works only with supporting OpenSSL version and IPv6 connectivity
     --ip <ip>                     a) tests the supplied <ip> v4 or v6 address instead of resolving host(s) in URI
                                   b) "one" means: just test the first DNS returns (useful for multiple IPs)
                                   c) "proxy" means: dns resolution via proxy. Needed when host has no DNS.
     -n, --nodns <min|none>        if "none": do not try any DNS lookups, "min" queries A, AAAA and MX records
     --sneaky                      leave less traces in target logs: user agent, referer
     --user-agent <user agent>     set a custom user agent instead of the standard user agent
     --ids-friendly                skips a few vulnerability checks which may cause IDSs to block the scanning IP
     --phone-out                   allow to contact external servers for CRL download and querying OCSP responder
     --add-ca <CA files|CA dir>    path to <CAdir> with *.pem or a comma separated list of CA files to include in trust check
     --mtls <CLIENT CERT file>     path to <CLIENT CERT> file in PEM format containing unencrypted certificate key (beta)
     --basicauth <user:pass>       provide HTTP basic auth information
     --reqheader <header>          add custom http request headers
     --rating-only                 test only the checks required for rating

output options (can also be preset via environment variables):
     --quiet                       don't output the banner. By doing this you acknowledge usage terms normally appearing in the banner
     --wide                        wide output for tests like RC4, BEAST. FS also with hexcode, kx, strength, RFC name
     --show-each                   for wide outputs: display all ciphers tested -- not only succeeded ones
     --mapping <openssl|           openssl: use the OpenSSL cipher suite name as the primary name cipher suite name form (default)
                iana|rfc             -> use the IANA/(RFC) cipher suite name as the primary name cipher suite name form
                no-openssl|          -> don't display the OpenSSL cipher suite name, display IANA/(RFC) names only
                no-iana|no-rfc>      -> don't display the IANA/(RFC) cipher suite name, display OpenSSL names only
     --color <0|1|2|3>             0: no escape or other codes,  1: b/w escape codes,  2: color (default), 3: extra color (color all ciphers)
     --colorblind                  swap green and blue in the output
     --debug <0-6>                 1: screen output normal but keeps debug output in /tmp/.  2-6: see "grep -A 5 '^DEBUG=' testssl.sh"
     --disable-rating              explicitly disables the rating output

file output options (can also be preset via environment variables)
     --log, --logging              logs stdout to '${NODE}-p${port}${YYYYMMDD-HHMM}.log' in current working directory (cwd)
     --logfile|-oL <logfile>       logs stdout to 'dir/${NODE}-p${port}${YYYYMMDD-HHMM}.log'. If 'logfile' is a dir or to a specified 'logfile'
     --json                        additional output of findings to flat JSON file '${NODE}-p${port}${YYYYMMDD-HHMM}.json' in cwd
     --jsonfile|-oj <jsonfile>     additional output to the specified flat JSON file or directory, similar to --logfile
     --json-pretty                 additional JSON structured output of findings to a file '${NODE}-p${port}${YYYYMMDD-HHMM}.json' in cwd
     --jsonfile-pretty|-oJ <jsonfile>  additional JSON structured output to the specified file or directory, similar to --logfile
     --csv                         additional output of findings to CSV file '${NODE}-p${port}${YYYYMMDD-HHMM}.csv' in cwd or directory
     --csvfile|-oC <csvfile>       additional output as CSV to the specified file or directory, similar to --logfile
     --html                        additional output as HTML to file '${NODE}-p${port}${YYYYMMDD-HHMM}.html'
     --htmlfile|-oH <htmlfile>     additional output as HTML to the specified file or directory, similar to --logfile
     --out(f,F)ile|-oa/-oA <fname> log to a LOG,JSON,CSV,HTML file (see nmap). -oA/-oa: pretty/flat JSON.
                                   "auto" uses '${NODE}-p${port}${YYYYMMDD-HHMM}'. If fname is a dir uses 'dir/${NODE}-p${port}${YYYYMMDD-HHMM}'
     --hints                       additional hints to findings
     --severity <severity>         severities with lower level will be filtered for CSV+JSON, possible values <LOW|MEDIUM|HIGH|CRITICAL>
     --append                      if (non-empty) <logfile>, <csvfile>, <jsonfile> or <htmlfile> exists, append to file. Omits any header
     --overwrite                   if <logfile>, <csvfile>, <jsonfile> or <htmlfile> exists it overwrites it without any warning
     --outprefix <fname_prefix>    before  '${NODE}.' above prepend <fname_prefix>


Options requiring a value can also be called with '=' e.g. testssl.sh -t=smtp --wide --openssl=/usr/bin/openssl <URI>.
<URI> always needs to be the last parameter.

userid@somehost:~ %

Details are in the man page.

More Screenshots /Pictures below

The pictures below still from an older version of testssl.sh.

You are free to check any port – supposed there's any SSL enabled service (TCP) listening. For the service HTTP you can also supply a full URL. STARTTLS services are those which are plaintext and need some kind of an upgrade command to speak TLS. This is very protocol (see difference between IMAP and SMTP) specific. A STARTTLS check with testssl.sh would be invoked with testssl.sh -t pop3 pop.o2online.de:110. Other examples: 
testssl.sh --starttls smtp <smtphost>.<tld>:587 
testssl.sh --starttls ftp <ftphost>.<tld>:21
testssl.sh -t xmpp <jabberhost>.<tld>:5222 
testssl.sh -t xmpp --xmpphost <XMPP domain> <jabberhost>.<tld>:5222 
testssl.sh --starttls imap <imaphost>.<tld>:143
The ports in those examples above are just the standard ports. Also here you're free to check any port. //refactor those, see e.g. https://content-security-policy.com/unsafe-hashes/ or just drop tis shit
If you just want to check the mail exchangers of a domain, do it like this: testssl.sh --mx google.com (make sure port 25 outbound is not blocked by your firewall) – see left hand side picture.

With the output option --wide you get where possible a wide output with hexcode of the cipher, OpenSSL cipher suite name, key exchange (with DH size), encryption algorithm, encryption bits size and maybe the RFC cipher suite name.

If you have the file mapping-rfc.txt in the same directory as testssl.sh it displays in the wide outputs also the corresponding RFC style cipher name. If you don't want this, you need to move mapping-rfc.txt away. Another thing: If you want to find out what local ciphers you have and print them pretty, use testssl.sh -V. Ever wondered what hexcode a cipher is? testssl.sh -V x14 lets you search for the hexcode x14. For hexcodes: If you just specify 14 instead of x14 you will get all ciphers returned which have 14 as a low, middle or high byte. For ciphers: You can also supply a word case pattern, e.g. testssl.sh -V CBC puts out every locally available cipher having the Cipher Block Chaining mode in its name.

testssl.sh -x <pattern> <URI> does the same as testssl.sh -V, it only checks the matched pattern at the server, so e.g. testssl.sh -x ECDH google.com checks google.com for ECDH ciphers (and lists also not available ones at the target), testssl.sh -x DHE smtp.posteo.de:465 does a similar thing for the TLS enabled SMTP service.

testssl.sh --file <myfile> let you do mass testing. The syntax of the file is very easy: one cmdline per line. Use comment signs # as you like, blank lines will be skipped, EOF signals the end of the file – what else? ;-).

You can also specify a proxy since version 2.6: testssl.sh --proxy=<proxyhost>:<proxyport> <your_other_cmds_here> will sneak the openssl and bash sockets requests e.g. out of our corporate environment. Proxy authentication is not supported and the port and protocol has to be allowed in the proxy.

Another neat feature: testssl.sh --header <URI> gives you some information on the HTTP header and marks security features in green (see upper black picture on the right hand side), not so good headers range from yellow over brown to red. It also allows you to fingerprint proxies, see lower black picture.


Changes

3.2




       ... branch is stable github only. Changes relative to 3.0 see changelog.

3.0






















Misc

Feedback, bugs and contributions are welcome! Currently there's one git repo at https://github.com/testssl/testssl.sh. Here @ https://testssl.sh you will always find the latest stable version.

Bugs (and fixes) as well as other PRs can by filed at the git repo or send me a mail to dirk aet testssl dot sh.

I post all significant updates on Mastodon or Bluesky. There was a personal twitter account which is deprecated as we don't like nazis or hate speech.  

Services:  If you need a scanning service or consulting get in touch with me..

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