testssl icon

Testing TLS/SSL encryption


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 22:02:23-- Directory
2.8/2018-Nov-15 22:46:12-- Directory
2.9.5/2020-Jan-23 22:04:09-- Directory
bleichenbacher/2018-Feb-23 18:00:33-- Directory
doc/2021-May-10 14:27:06-- Directory
etc/2021-May-10 14:26:48-- Directory
openssl-1.0.2i-chacha.pm.ipv6.contributed/2020-Sep-17 09:55:59-- Directory
utils/2021-May-10 14:34:02-- Directory
CHANGELOG.md2020-Jan-23 21:57:3817.14KB MD File
CREDITS.md2020-Jan-23 21:57:383.90KB MD File
Dockerfile2020-Jan-04 10:42:18404.00B Unknown File
Dockerfile.md2019-Dec-14 09:35:381.24KB MD File
LICENSE.txt2014-May-03 11:04:2217.59KB TXT Type Document
OPENSSL-LICENSE.txt2017-May-09 13:14:166.13KB TXT Type Document
Readme.md2020-Jan-23 22:12:095.55KB MD File
openssl-1.0.2k-chacha.pm.ipv6.Linux+FreeBSD.201705.tar.gz2017-May-12 18:11:029.51MB GZ Compressed Archive
openssl-1.0.2k-chacha.pm.ipv6.Linux+FreeBSD.201705.tar.gz.asc2017-May-12 18:11:04811.00B ASC File
openssl-1.0.2k-dev-chacha.pm.ipv6.Linux+FreeBSD.tar.gz2017-Jul-19 09:28:309.51MB GZ Compressed Archive
openssl-1.0.2k-dev-chacha.pm.ipv6.Linux+FreeBSD.tar.gz.asc2017-Jul-19 09:28:38811.00B ASC File
openssl-iana.mapping.html2021-May-10 14:05:3860.80KB HTML File
openssl-ms14-066.Linux.x86_642016-Apr-15 12:36:234.24MB X86_64 File
testssl-3.0.5.tar.gz2021-May-10 14:09:398.80MB GZ Compressed Archive
testssl-3.0.5.tar.gz.asc2021-May-10 14:09:39508.00B ASC File
testssl.1.html2021-May-10 14:12:1257.28KB HTML File
testssl.sh2021-May-10 14:05:38983.44KB SH File
testssl.sh.asc2021-May-10 14:07:15508.00B ASC File
testssl_german_owasp_day.pdf2018-Nov-18 13:53:381.11MB PDF Type Document

Key features


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


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 not support the project with a donation? It helps keeping the project alive and kicking.

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.


github Development takes place at github. We're now @ 3.1dev. As of 2019, you should use the 3.0 version as 2.9.5 is not supported anymore As I do releases on github you can pull the zip for a stable release from there.

Jan 23,2020: Version 3.0. Final 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.

Screenshots /Pictures here

The pictures are still from an older version of testssl.sh. This will be updated later. It should suffice to get a picture though.

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/drwetter/testssl.sh/tree/3.0/etc.


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:
[email protected]somehost:~ % testssl.sh

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

"testssl.sh <options>", where <options> is:

     --help                        what you're looking at
     -b, --banner                  displays banner + version of testssl.sh
     -v, --version                 same as previous
     -V, --local                   pretty print all local ciphers
     -V, --local <pattern>         which local ciphers with <pattern> are available? If pattern is not a number: word match

     <pattern>                     is always an ignore case word pattern of cipher hexcode or any other string in the name, kx or bits

"testssl.sh <URI>", where <URI> is:

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

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

     -t, --starttls <protocol>     Does a default run against a STARTTLS enabled <protocol,
                                   protocol is <ftp|smtp|lmtp|pop3|imap|xmpp|telnet|ldap|nntp|postgres|mysql>
     --xmpphost <to_domain>        For STARTTLS enabled XMPP it supplies the XML stream to-'' domain -- sometimes needed
     --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
     --connect-timeout <seconds>   useful to avoid hangers. Max <seconds> to wait for the TCP socket connect to return
     --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, --standard         tests certain lists of cipher suites by strength
     -p, --protocols               checks TLS/SSL protocols (including SPDY/HTTP2)
     -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
     -BB, --robot                  tests for Return of Bleichenbacher's Oracle Threat (ROBOT) vulnerability
     -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
     -F, --freak                   tests for FREAK vulnerability
     -J, --logjam                  tests for LOGJAM vulnerability
     -D, --drown                   tests for DROWN vulnerability
     -f, --pfs, --fs, --nsa        checks (perfect) forward secrecy settings
     -4, --rc4, --appelbaum        which RC4 ciphers are being offered?

tuning / connect options (most also can be preset via environment variables):
     --fast                        omits some checks: using openssl for all ciphers (-e), show only first preferred cipher.
     -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                  fallback to checks with OpenSSL where sockets are normally used
     --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)
     -6                            also use IPv6. 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) arg "one" means: just test the first DNS returns (useful for multiple IPs)
     -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
     --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 <cafile>             path to <cafile> or a comma separated list of CA files enables test against additional CAs.
     --basicauth <user:pass>       provide HTTP basic auth information.

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. PFS 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"

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}${YYYYMMDD-HHMM}'. If fname if a dir uses 'dir/${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
     --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.

[email protected]somehost:~ % 

Details are in the man page.

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.
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.




Feedback, bugs and contributions are welcome! Currently there's one git repo at https://github.com/drwetter/testssl.sh. Here @ https://testssl.sh you will always find the latest stable version. At github in the 2.9dev branch is the latest'n'greatest development 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 Twitter (@drwetter).  

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