DE

↑ ↓ select, Enter open, Esc close

Check whether a server supports TLS 1.3

harmlessSSL and certificatesalle
Adjust the values, the command updates live
user@server
openssl s_client -connect example.com:443 -servername example.com -tls1_3 </dev/null 2>/dev/null | grep -E "^New,|Protocol *:"

Connects using TLS 1.3 only and prints the negotiated protocol and cipher suite, such as TLSv1.3 with TLS_AES_256_GCM_SHA384. If the output is empty or shows Cipher is (NONE), the server does not speak TLS 1.3. Use -tls1_2 to test the older version the same way.

Note: Outdated protocols like TLS 1.0 cannot be tested reliably this way, because the local OpenSSL often no longer offers them itself.

Also searched as

  • check if tls 1.3 is enabled
  • which tls versions does a server support
  • test tls protocol openssl

Related one-liners

All in SSL and certificates

Test an SMTP connection with STARTTLS and certificate

$openssl s_client -connect mail.example.com:587 -starttls smtp -servername mail.example.com
harmlessMail

Check the contents of a CSR before submitting it

$openssl req -in example.com.csr -noout -text -verify
harmlessSSL and certificates

Check the SSL certificate expiration date of a website

$openssl s_client -connect example.com:443 -servername example.com </dev/null 2>/dev/null | openssl x509 -noout -dates
harmlessSSL and certificates

Check whether a certificate expires within the next days

#openssl x509 -in /etc/letsencrypt/live/example.com/cert.pem -noout -checkend $(( 30 * 86400 )) && echo "noch gültig" || echo "läuft bald ab"
harmlessSSL and certificates

Check whether a private key matches a certificate

#openssl x509 -noout -modulus -in /etc/ssl/certs/example.com.crt | openssl md5 && openssl rsa -noout -modulus -in /etc/ssl/private/example.com.key | openssl md5
harmlessSSL and certificates

Check whether a website's certificate is trusted

$openssl s_client -connect example.com:443 -servername example.com -verify_hostname example.com </dev/null 2>/dev/null | grep "Verify return code"
harmlessSSL and certificates

Read first, then run.

The commands on myline.de act directly on servers, files and databases. A wrong path or placeholder can delete data irreversibly or make a server unreachable.

  • All commands are provided without warranty and are not tested on every system.
  • Understand what a command does before running it, and check every placeholder.
  • Make a backup first and, if possible, try it on a test system.
  • You run commands at your own risk. Liability for damages is excluded to the extent permitted by law.