Melhttps://unixcop.com
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OpenSSL: Check SSL Certificate Expiration Date and Get more info

I will keep this tutorial short and easy to follow. With OpenSSL commands, So we can get much information from a https site like the certificate expiration date, the issuer of the certificates and fingerprint, and more things Lets start now .

So How to get Full ssl information data from an https site

openssl s_client -servername NAME -connect HOST:PORT

-servername is optional but you can use it to put the fqdn name

-connect host:port . it the website and port in most situations is 443, else put the real SSL port

Also Get full Certificate data with OpenSSL

openssl s_client -servername unixcop.com  -connect unixcop.com:443
CONNECTED(00000004)
depth=2 C = US, O = Internet Security Research Group, CN = ISRG Root X1
verify return:1
depth=1 C = US, O = Let's Encrypt, CN = R3
verify return:1
depth=0 CN = unixcop.com
verify return:1
---
Certificate chain
 0 s:CN = unixcop.com
   i:C = US, O = Let's Encrypt, CN = R3
 1 s:C = US, O = Let's Encrypt, CN = R3
   i:C = US, O = Internet Security Research Group, CN = ISRG Root X1
 2 s:C = US, O = Internet Security Research Group, CN = ISRG Root X1
   i:O = Digital Signature Trust Co., CN = DST Root CA X3
---
Server certificate
-----BEGIN CERTIFICATE-----
MIIFLTCCBBWgAwIBAgISBFQRFmfTSdVTX55lc1IttlfZMA0GCSqGSIb3DQEBCwUA
MDIxCzAJBgNVBAYTAlVTMRYwFAYDVQQKEw1MZXQncyBFbmNyeXB0MQswCQYDVQQD
EwJSMzAeFw0yMTA4MjAxNDIwNTJaFw0yMTExMTgxNDIwNTFaMBYxFDASBgNVBAMT
C3VuaXhjb3AuY29tMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA0Mbt
LWf/Eu/1JzFoDSWKg/qFkOl5ByjIZ5EcGi8jv6EeDIToYNbgVHdcbSszigIyv6Z4
/CvZuxyAlOqBhxjKhtL4zuPFgLuE2UEX5dyiBP0MzuNR/xFXX/3iaJKoptuQTmJJ
FZ1fwWHsPWtGvI8ZGdBH8r0rPMvACcs0+SDDF3/tcpQg2tz3hxZwFTuWyQ8zQvui
XHtq724gjPGvr3huJ74Q6d/Uj/pgrHHFyke+f0FvlUnUdVT8UeTIlz7WOKP/cieh
NpJ+S7FyPaxuztuJqBwQwQtXHy8NNcZyzVMqOtGnODJG/k9WqrpvZgpig+b9ReQT
iV8XpJO7MeGESTB1cwIDAQABo4ICVzCCAlMwDgYDVR0PAQH/BAQDAgWgMB0GA1Ud
JQQWMBQGCCsGAQUFBwMBBggrBgEFBQcDAjAMBgNVHRMBAf8EAjAAMB0GA1UdDgQW
BBSWxY3A0mjbpTe02TPrp+y/vWkcaDAfBgNVHSMEGDAWgBQULrMXt1hWy65QCUDm
H6+dixTCxjBVBggrBgEFBQcBAQRJMEcwIQYIKwYBBQUHMAGGFWh0dHA6Ly9yMy5v
LmxlbmNyLm9yZzAiBggrBgEFBQcwAoYWaHR0cDovL3IzLmkubGVuY3Iub3JnLzAn
BgNVHREEIDAeggt1bml4Y29wLmNvbYIPd3d3LnVuaXhjb3AuY29tMEwGA1UdIARF
MEMwCAYGZ4EMAQIBMDcGCysGAQQBgt8TAQEBMCgwJgYIKwYBBQUHAgEWGmh0dHA6
Ly9jcHMubGV0c2VuY3J5cHQub3JnMIIBBAYKKwYBBAHWeQIEAgSB9QSB8gDwAHUA
RJRlLrDuzq/EQAfYqP4owNrmgr7YyzG1P9MzlrW2gagAAAF7ZCaLIwAABAMARjBE
AiAFljtSwllL7T20p2oOAKXiemCvk3mYURJLqULiEdI7VQIgVwzoGReeSFFPJB8N
urF+Q8npj/giaucw3q0dTbXHTSAAdwB9PvL4j/+IVWgkwsDKnlKJeSvFDngJfy5q
l2iZfiLw1wAAAXtkJosyAAAEAwBIMEYCIQDL4Cw/6iK8pWFlATSBdlkQtVj2hrKk
QDLZuw2wELXlmgIhAPRE9slgsqH8Bt5LlGAJ2CLeFQYxs79IZuuwxxMDFTRWMA0G
CSqGSIb3DQEBCwUAA4IBAQB5BTtp1BzuNCHEoi/S4ESt9O5gnu3KieMpWQ9ranH8
7XFgK+b4KNcy4r/H399u+auLhBxC4/+cR91Dh6hpTERhrcjENnWrTLgUrnSX/Kse
nsrFOUggjx12zB7hcC+iENixbFRjREDZOWZ9HOPEiaw6+GhFYEVRR9drpihamvQu
P0GBheT712z95yAc4BkiTUN5JBlj4D0f/zhIzpIPkJoYY+oxJ8qMmSUgD8wrtzVD
MqlcJWrQoZycLB7ZxICG9uqkCFoij+LaFaQsoIWElXMpsQ5Yo+AUkZeLF5R6HZE4
Q9CNy8wYRMsO1SYtMMmqI1jitdrVWsTacPcJhSjtPDFV
-----END CERTIFICATE-----
subject=CN = unixcop.com

issuer=C = US, O = Let's Encrypt, CN = R3

---
No client certificate CA names sent
Peer signing digest: SHA256
Peer signature type: RSA-PSS
Server Temp Key: X25519, 253 bits
---
SSL handshake has read 4674 bytes and written 408 bytes
Verification: OK
---
New, TLSv1.2, Cipher is ECDHE-RSA-CHACHA20-POLY1305
Server public key is 2048 bit
Secure Renegotiation IS supported
Compression: NONE
Expansion: NONE
No ALPN negotiated
SSL-Session:
    Protocol  : TLSv1.2
    Cipher    : ECDHE-RSA-CHACHA20-POLY1305
    Session-ID: CFDB4E84054B0B5F580C96198CE25DAFE3BD7FE54DC92B03B6C4482D324D1D43
    Session-ID-ctx:
    Master-Key: 825683C91BB0D2EA44E38C57446D5B9896CFB7B23CD5E5F3CCD070C09A56E5B00655BC686D31E4954A7D889EF21D2083
    PSK identity: None
    PSK identity hint: None
    SRP username: None
    TLS session ticket lifetime hint: 86400 (seconds)
    TLS session ticket:
    0000 - 98 a5 75 00 cb 44 c0 4d-ce 6f c2 1e b1 b9 6e 48   ..u..D.M.o....nH
    0010 - 25 69 11 0d 46 d0 e5 c5-e5 1e 1e 45 1d 06 8a cf   %i..F......E....
    0020 - 56 5c 4c 30 37 f6 7a a3-56 5d 5c 75 a0 d2 7f 71   V\L07.z.V]\u...q
    0030 - 53 b1 f7 a1 41 3e 95 01-12 95 30 05 cc 30 a0 f1   S...A>....0..0..
    0040 - 7e b7 44 14 3c c2 8e 77-66 48 bc a7 b1 f5 96 62   ~.D.<..wfH.....b
    0050 - ce 1b 9c 35 e8 17 fc 61-4b 7b a3 60 d7 b8 bd 76   ...5...aK{.`...v
    0060 - dc 54 71 95 3a 4d 7f 13-07 bd 4c 20 95 7a c5 a5   .Tq.:M....L .z..
    0070 - 84 42 56 aa 7b 02 22 59-56 3a 11 3d 5f ee e5 1a   .BV.{."YV:.=_...
    0080 - 7d 80 c1 1a 7b 74 56 cd-89 cf 2e 7f 5a fd 2f 81   }...{tV.....Z./.
    0090 - 0a 8e 14 88 14 be ae 4b-3d 03 83 49 d8 c9 a0 cc   .......K=..I....
    00a0 - ac 0b 07 ff 06 4e 8e cc-8b a4 48 b2 03 10 30 29   .....N....H...0)
    00b0 - 56 9f f5 ca fa ca 80 75-a5 fd 61 1a 9a 2d 17 40   V......u..a..-.@

    Start Time: 1633592990
    Timeout   : 7200 (sec)
    Verify return code: 0 (ok)
    Extended master secret: yes
---
closed

OpenSSL: Check SSL Certificate Expiration Date

So Please run the command to see the expiration in one command

echo| openssl s_client -connect www.google.com:443 2> /dev/null | openssl x509 -noout -dates
notBefore=Sep 13 04:07:13 2021 GMT
notAfter=Nov 20 04:07:12 2021 GMT

Find the SSL Certificate issuer

echo | openssl s_client -connect www.unixcop.com:443 2> /dev/null| openssl x509 -noout -issuer

Find whom the SSL certificate is issued to

echo| openssl s_client -connect www.unixcop.com:443 2> /dev/null | openssl x509 -noout -subject

Get above things at once.

echo | openssl s_client -connect www.unixcop.com:443  2> /dev/null | openssl x509 -noout -issuer -subject -dates

Show the SHA1 fingerprint of the SSL certificate

echo|openssl s_client -connect www.unixcop.com:443 2>/dev/null|openssl x509 -noout -fingerprint
SHA1 Fingerprint=94:D8:81:F7:97:AD:31:F9:BB:56:74:F8:A1:1B:97:50:64:1F:F5:85

Extract all information from the SSL certificate

echo|openssl s_client -connect www.unixcop.com:443 2>/dev/null|openssl x509  -noout -text

Show the SSL certificate itself 

echo|openssl s_client -connect www.unixcop.com:443 2>/dev/null|openssl x509

In addition to here are the most used options with openssl you can see things with man openssl



Option

Description
-textPrints out the certificate in text form.
-nooutPrevents output of the encoded version of the request.
-subjectOutputs the name.
-issuerOutputs the issuer name.
-datesPrints out the start and expiry dates of a certificate.
-fingerprintPrints out the digest of the DER encoded version of the whole certificate.

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