Certificates : Getting the thumbprint via OpenSSL

I've been looking at AWS Cognito and keep coming across interesting snippets of how to do things.

Let's say you wanted the ADFS thumbprint for the SSL certificate.

You could do this via mmc or via the ADFS wizard or via the IIS binding.

You could also do:

openssl s_client -showcerts -connect my-adfs:443

Note: You just use the top-level ADFS URL - don't add /adfs/ls etc.

This displays:

Loading 'screen' into random state - done
CONNECTED(000005DC)
depth=0 CN = my-adfs
verify error:num=18:self signed certificate
verify return:1
depth=0 CN = my-adfs
verify return:1
---
Certificate chain
 0 s:/CN=my-adfs
   i:/CN=my-adfs
-----BEGIN CERTIFICATE-----
MIIExD...vLMng0
-----END CERTIFICATE-----
---
Server certificate
subject=/CN=my-adfs
issuer=/CN=my-adfs
---
No client certificate CA names sent
---
SSL handshake has read 1964 bytes and written 447 bytes
---
New, TLSv1/SSLv3, Cipher is ECDHE-RSA-AES256-GCM-SHA384
Server public key is 4096 bit
Secure Renegotiation IS supported
Compression: NONE
Expansion: NONE
SSL-Session:
    Protocol  : TLSv1.2
    Cipher    : ECDHE-RSA-AES256-GCM-SHA384
    Session-ID: 29140000...E4D79A337F1F0BBC9

    Session-ID-ctx:
    Master-Key: 91E8...DE30CD
    Key-Arg   : None
    PSK identity: None
    PSK identity hint: None
    SRP username: None
    Start Time: 1521150875
    Timeout   : 300 (sec)
    Verify return code: 18 (self signed certificate)
---
read:errno=10054

Copy / paste this section:

-----BEGIN CERTIFICATE-----
MIIExD...vLMng0
-----END CERTIFICATE-----

into a file called e.g. adfs.cer

Then:

openssl x509 -in c:\xxx\adfs.cer -fingerprint -noout

SHA1 Fingerprint=24:F8:...:9A:21:2B:35 

Enjoy!