Mac OS X: View the details of a websites supported TLS certificates from terminal

The below script will give you basic information on a websites certificate:

$ curl --insecure -vvI https://andrewbaker.ninja 2>&1 | awk 'BEGIN { cert=0 } /^\* SSL connection/ { cert=1 } /^\*/ { if (cert) print }'
* SSL connection using TLSv1.3 / TLS_AES_256_GCM_SHA384
* ALPN, server accepted to use http/1.1
* Server certificate:
*  subject: CN=andrewbaker.ninja
*  start date: Nov  4 23:00:13 2022 GMT
*  expire date: Feb  2 23:00:12 2023 GMT
*  issuer: C=US; O=Let's Encrypt; CN=R3
*  SSL certificate verify result: unable to get local issuer certificate (20), continuing anyway.
* TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
* TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
* old SSL session ID is stale, removing
* Mark bundle as not supporting multiuse
* Connection #0 to host andrewbaker.ninja left intact

NMAP is provides a simple way to get a list of available ciphers from a host website / server. Additionally, nmap provides a strength rating of strong, weak, or unknown for each available cipher. First, download the ssl-enum-ciphers.nse nmap script (explanation here). Then from the same directory as the script, run nmap as follows:

$ nmap --script ssl-enum-ciphers -p 443 andrewbaker.ninja
Starting Nmap 7.93 ( https://nmap.org ) at 2023-05-11 10:40 SAST
Nmap scan report for andrewbaker.ninja (13.244.140.33)
Host is up (0.051s latency).
rDNS record for 13.244.140.33: ec2-13-244-140-33.af-south-1.compute.amazonaws.com

PORT    STATE SERVICE
443/tcp open  https
| ssl-enum-ciphers:
|   TLSv1.0:
|     ciphers:
|       TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (secp256r1) - A
|       TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (secp256r1) - A
|       TLS_RSA_WITH_AES_256_CBC_SHA (rsa 2048) - A
|       TLS_RSA_WITH_AES_128_CBC_SHA (rsa 2048) - A
|       TLS_DHE_RSA_WITH_AES_256_CBC_SHA (dh 2048) - A
|       TLS_DHE_RSA_WITH_AES_128_CBC_SHA (dh 2048) - A
|     compressors:
|       NULL
|     cipher preference: server
|   TLSv1.1:
|     ciphers:
|       TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (secp256r1) - A
|       TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (secp256r1) - A
|       TLS_RSA_WITH_AES_256_CBC_SHA (rsa 2048) - A
|       TLS_RSA_WITH_AES_128_CBC_SHA (rsa 2048) - A
|       TLS_DHE_RSA_WITH_AES_256_CBC_SHA (dh 2048) - A
|       TLS_DHE_RSA_WITH_AES_128_CBC_SHA (dh 2048) - A
|     compressors:
|       NULL
|     cipher preference: server
|   TLSv1.2:
|     ciphers:
|       TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (secp256r1) - A
|       TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (secp256r1) - A
|       TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (secp256r1) - A
|       TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (secp256r1) - A
|       TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 (secp256r1) - A
|       TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 (secp256r1) - A
|       TLS_RSA_WITH_AES_256_GCM_SHA384 (rsa 2048) - A
|       TLS_RSA_WITH_AES_128_GCM_SHA256 (rsa 2048) - A
|       TLS_RSA_WITH_AES_256_CBC_SHA (rsa 2048) - A
|       TLS_RSA_WITH_AES_128_CBC_SHA (rsa 2048) - A
|       TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 (dh 2048) - A
|       TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 (dh 2048) - A
|       TLS_DHE_RSA_WITH_AES_256_CBC_SHA256 (dh 2048) - A
|       TLS_DHE_RSA_WITH_AES_128_CBC_SHA256 (dh 2048) - A
|       TLS_DHE_RSA_WITH_AES_256_CBC_SHA (dh 2048) - A
|       TLS_DHE_RSA_WITH_AES_128_CBC_SHA (dh 2048) - A
|     compressors:
|       NULL
|     cipher preference: server
|   TLSv1.3:
|     ciphers:
|       TLS_AKE_WITH_AES_256_GCM_SHA384 (secp256r1) - A
|       TLS_AKE_WITH_CHACHA20_POLY1305_SHA256 (secp256r1) - A
|       TLS_AKE_WITH_AES_128_GCM_SHA256 (secp256r1) - A
|     cipher preference: server
|_  least strength: A

Nmap done: 1 IP address (1 host up) scanned in 9.61 seconds

Next up (and probably my favourite), sslscan is a really decent tool because it tests connecting with TLS and SSL including obsolete SSL versions. It then reports about the server’s cipher suites and certificate.

$ brew install sslscan
$ sslscan andrewbaker.ninja
Version: 2.0.15
OpenSSL 3.0.7 1 Nov 2022

Connected to 13.244.140.33

Testing SSL server andrewbaker.ninja on port 443 using SNI name andrewbaker.ninja

  SSL/TLS Protocols:
SSLv2     disabled
SSLv3     disabled
TLSv1.0   enabled
TLSv1.1   enabled
TLSv1.2   enabled
TLSv1.3   enabled

  TLS Fallback SCSV:
Server supports TLS Fallback SCSV

  TLS renegotiation:
Secure session renegotiation supported

  TLS Compression:
OpenSSL version does not support compression
Rebuild with zlib1g-dev package for zlib support

  Heartbleed:
TLSv1.3 not vulnerable to heartbleed
TLSv1.2 not vulnerable to heartbleed
TLSv1.1 not vulnerable to heartbleed
TLSv1.0 not vulnerable to heartbleed

  Supported Server Cipher(s):
Preferred TLSv1.3  256 bits  TLS_AES_256_GCM_SHA384        Curve P-256 DHE 256
Accepted  TLSv1.3  256 bits  TLS_CHACHA20_POLY1305_SHA256  Curve P-256 DHE 256
Accepted  TLSv1.3  128 bits  TLS_AES_128_GCM_SHA256        Curve P-256 DHE 256
Preferred TLSv1.2  256 bits  ECDHE-RSA-AES256-GCM-SHA384   Curve P-256 DHE 256
Accepted  TLSv1.2  128 bits  ECDHE-RSA-AES128-GCM-SHA256   Curve P-256 DHE 256
Accepted  TLSv1.2  128 bits  ECDHE-RSA-AES128-SHA          Curve P-256 DHE 256
Accepted  TLSv1.2  256 bits  ECDHE-RSA-AES256-SHA          Curve P-256 DHE 256
Accepted  TLSv1.2  128 bits  ECDHE-RSA-AES128-SHA256       Curve P-256 DHE 256
Accepted  TLSv1.2  256 bits  ECDHE-RSA-AES256-SHA384       Curve P-256 DHE 256
Accepted  TLSv1.2  256 bits  AES256-GCM-SHA384
Accepted  TLSv1.2  128 bits  AES128-GCM-SHA256
Accepted  TLSv1.2  256 bits  AES256-SHA
Accepted  TLSv1.2  128 bits  AES128-SHA
Accepted  TLSv1.2  256 bits  DHE-RSA-AES256-GCM-SHA384     DHE 2048 bits
Accepted  TLSv1.2  128 bits  DHE-RSA-AES128-GCM-SHA256     DHE 2048 bits
Accepted  TLSv1.2  256 bits  DHE-RSA-AES256-SHA256         DHE 2048 bits
Accepted  TLSv1.2  128 bits  DHE-RSA-AES128-SHA256         DHE 2048 bits
Accepted  TLSv1.2  256 bits  DHE-RSA-AES256-SHA            DHE 2048 bits
Accepted  TLSv1.2  128 bits  DHE-RSA-AES128-SHA            DHE 2048 bits
Preferred TLSv1.1  128 bits  ECDHE-RSA-AES128-SHA          Curve P-256 DHE 256
Accepted  TLSv1.1  256 bits  ECDHE-RSA-AES256-SHA          Curve P-256 DHE 256
Accepted  TLSv1.1  256 bits  AES256-SHA
Accepted  TLSv1.1  128 bits  AES128-SHA
Accepted  TLSv1.1  256 bits  DHE-RSA-AES256-SHA            DHE 2048 bits
Accepted  TLSv1.1  128 bits  DHE-RSA-AES128-SHA            DHE 2048 bits
Preferred TLSv1.0  128 bits  ECDHE-RSA-AES128-SHA          Curve P-256 DHE 256
Accepted  TLSv1.0  256 bits  ECDHE-RSA-AES256-SHA          Curve P-256 DHE 256
Accepted  TLSv1.0  256 bits  AES256-SHA
Accepted  TLSv1.0  128 bits  AES128-SHA
Accepted  TLSv1.0  256 bits  DHE-RSA-AES256-SHA            DHE 2048 bits
Accepted  TLSv1.0  128 bits  DHE-RSA-AES128-SHA            DHE 2048 bits

  Server Key Exchange Group(s):
TLSv1.3  128 bits  secp256r1 (NIST P-256)
TLSv1.3  192 bits  secp384r1 (NIST P-384)
TLSv1.3  260 bits  secp521r1 (NIST P-521)
TLSv1.2  128 bits  secp256r1 (NIST P-256)
TLSv1.2  192 bits  secp384r1 (NIST P-384)
TLSv1.2  260 bits  secp521r1 (NIST P-521)

  SSL Certificate:
Signature Algorithm: sha256WithRSAEncryption
RSA Key Strength:    2048

Subject:  andrewbaker.ninja
Altnames: DNS:andrewbaker.ninja, DNS:www.andrewbaker.ninja
Issuer:   Zscaler Intermediate Root CA (zscaler.net) (t)

Not valid before: May  6 06:30:35 2023 GMT
Not valid after:  May 20 06:30:35 2023 GMT

If you want a detailed dump of the certificate run (you will need openssl installed):

$ openssl s_client -connect andrewbaker.ninja:443 </dev/null 2>/dev/null | openssl x509 -inform pem -text
Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number:
            03:bd:20:6e:ef:67:55:93:2a:a8:90:9f:40:e4:b2:a8:c0:fe
        Signature Algorithm: sha256WithRSAEncryption
        Issuer: C = US, O = Let's Encrypt, CN = R3
        Validity
            Not Before: Nov  4 23:00:13 2022 GMT
            Not After : Feb  2 23:00:12 2023 GMT
        Subject: CN = andrewbaker.ninja
        Subject Public Key Info:
            Public Key Algorithm: id-ecPublicKey
                Public-Key: (256 bit)
                pub:
                    04:c8:30:00:b3:f0:fb:03:10:90:57:4a:df:7f:28:
                    34:b9:2e:94:1a:28:29:41:2b:88:48:3b:c0:48:2a:
                    f0:62:3d:57:0d:32:db:30:9b:c5:98:11:b3:14:a7:
                    a8:e0:30:1d:d7:ec:cc:86:6f:d2:f1:7b:a4:70:9c:
                    98:e0:63:34:ae
                ASN1 OID: prime256v1
                NIST CURVE: P-256
        X509v3 extensions:
            X509v3 Key Usage: critical
                Digital Signature
            X509v3 Extended Key Usage:
                TLS Web Server Authentication, TLS Web Client Authentication
            X509v3 Basic Constraints: critical
                CA:FALSE
            X509v3 Subject Key Identifier:
                B9:28:D2:09:38:B0:B1:03:77:DA:8F:C6:AD:2E:51:EF:0F:7F:23:4F
            X509v3 Authority Key Identifier:
                keyid:14:2E:B3:17:B7:58:56:CB:AE:50:09:40:E6:1F:AF:9D:8B:14:C2:C6

            Authority Information Access:
                OCSP - URI:http://r3.o.lencr.org
                CA Issuers - URI:http://r3.i.lencr.org/

            X509v3 Subject Alternative Name:
                DNS:andrewbaker.ninja, DNS:www.andrewbaker.ninja
            X509v3 Certificate Policies:
                Policy: 2.23.140.1.2.1
                Policy: 1.3.6.1.4.1.44947.1.1.1
                  CPS: http://cps.letsencrypt.org

            CT Precertificate SCTs:
                Signed Certificate Timestamp:
                    Version   : v1 (0x0)
                    Log ID    : B7:3E:FB:24:DF:9C:4D:BA:75:F2:39:C5:BA:58:F4:6C:
                                5D:FC:42:CF:7A:9F:35:C4:9E:1D:09:81:25:ED:B4:99
                    Timestamp : Nov  5 00:00:13.652 2022 GMT
                    Extensions: none
                    Signature : ecdsa-with-SHA256
                                30:46:02:21:00:89:98:62:15:D5:40:1D:80:9D:40:4B:
                                31:B1:E3:C5:3B:65:41:11:4D:98:D2:E1:23:16:45:0D:
                                DA:08:FE:72:AB:02:21:00:A7:F0:5D:49:63:4F:91:4C:
                                CF:60:8D:FF:26:F6:0B:1B:0C:47:9C:B6:70:57:7C:68:
                                AB:F0:9B:35:48:34:08:A4
                Signed Certificate Timestamp:
                    Version   : v1 (0x0)
                    Log ID    : 7A:32:8C:54:D8:B7:2D:B6:20:EA:38:E0:52:1E:E9:84:
                                16:70:32:13:85:4D:3B:D2:2B:C1:3A:57:A3:52:EB:52
                    Timestamp : Nov  5 00:00:14.177 2022 GMT
                    Extensions: none
                    Signature : ecdsa-with-SHA256
                                30:45:02:21:00:E1:8B:7F:3F:75:05:20:8A:27:3D:30:
                                64:BB:4B:FE:EF:24:C9:7E:85:6C:6D:DF:16:ED:BE:23:
                                9C:97:67:E1:DD:02:20:60:89:B6:D9:0F:BE:C4:E0:7B:
                                05:E1:EE:6D:0B:2D:78:C9:58:AA:0F:10:C0:34:FE:79:
                                FA:63:DD:2D:50:01:5B
    Signature Algorithm: sha256WithRSAEncryption
         4a:54:e0:ec:05:b8:58:ef:44:de:a8:5f:89:fc:1d:cb:86:39:
         05:1d:d3:b2:57:73:bd:6d:11:e5:c2:fd:cd:1a:6b:ee:62:11:
         f8:94:6b:22:b9:16:d6:e3:95:ed:04:9e:7c:ba:1b:3e:5f:dc:
         4f:a0:ae:58:ec:3c:25:a0:41:a5:c8:b9:c8:7a:3c:2f:1f:17:
         60:e8:7d:f0:a2:8e:0d:45:cb:7b:b1:06:13:75:3b:b0:cb:f6:
         6e:2f:71:70:6a:55:96:34:58:db:42:06:5a:7f:78:00:8f:7d:
         e3:83:02:30:82:49:52:38:da:07:6b:c3:ba:ad:09:1e:7e:33:
         0c:f5:0b:49:33:9d:b7:4e:1a:16:c2:ef:47:6f:ec:02:03:4a:
         84:75:bb:30:6e:8a:b4:22:da:d6:ac:43:5d:9b:3c:8b:2a:13:
         af:2b:2e:ab:02:58:dd:80:73:04:8c:dc:2e:48:71:ae:57:c4:
         0e:40:8c:6d:52:b5:91:0c:6b:0d:5e:98:01:6f:09:d1:3a:1b:
         41:7c:70:cc:66:9a:89:b3:b7:27:3d:6f:62:10:66:bb:63:67:
         59:08:ed:7e:c0:c3:31:1c:89:dd:ce:f2:6f:42:fd:42:21:94:
         c3:27:6e:d9:ea:d1:5f:5a:6f:58:26:eb:3e:ba:a6:ee:ed:45:
         00:99:e3:9e
-----BEGIN CERTIFICATE-----
MIIEdTCCA12gAwIBAgISA70gbu9nVZMqqJCfQOSyqMD+MA0GCSqGSIb3DQEBCwUA
MDIxCzAJBgNVBAYTAlVTMRYwFAYDVQQKEw1MZXQncyBFbmNyeXB0MQswCQYDVQQD
EwJSMzAeFw0yMjExMDQyMzAwMTNaFw0yMzAyMDIyMzAwMTJaMBwxGjAYBgNVBAMT
EWFuZHJld2Jha2VyLm5pbmphMFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEyDAA
s/D7AxCQV0rffyg0uS6UGigpQSuISDvASCrwYj1XDTLbMJvFmBGzFKeo4DAd1+zM
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BggrBgEFBQcDAQYIKwYBBQUHAwIwDAYDVR0TAQH/BAIwADAdBgNVHQ4EFgQUuSjS
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Z1kI7X7AwzEcid3O8m9C/UIhlMMnbtnq0V9ab1gm6z66pu7tRQCZ454=
-----END CERTIFICATE-----