Scripting OpenSSL just to extract Certificate Chain and Cert Expiry date

usecase

  • The concern is documenting the need to quickly check the
  • certificate chain
  • certificate expiry date
  • using a single command from PowerShell with OpenSSL

1. steps

function test-certificate($domain) {
$domain += ":443"
openssl s_client -connect $domain | sls "certificate chain" -Context 5
openssl
  • and
openssl s_client -connect github.com:443 | openssl x509 -noout -enddate

2. passing the “Q” key into the command

  • s_client opens the client that is awaiting for the input
  • I need to pass the q into the script for the s_client to end gracefully and immediatelly
  • which is achieved with write-output "q" | ...
  • echo is alias for write-output cmdlet
echo "q" | openssl s_client -connect github:443

3. solution

  • just adding the following to the $profile
  • passing the domain e.g. cert github.com and pressing Q to continue
  • this is just for a quick interactive check
#$profile
function test-certificate($domain, $contextLength = 10) {

$domain += ":443"
echo "q" | openssl s_client -connect $domain | openssl x509 -noout -enddate | sls "notAfter.*"
echo "q" | openssl s_client -connect $domain | sls "certificate chain" -Context $contextLength
write-host "~~~" -ForegroundColor darkcyan
write-host "If needed, pass a desired output length after domainname" -ForegroundColor darkcyan
}
Set-Alias cert test-certificate

4. sources

today I learnt… | as a support eng of the wonderful Snowplow Analytics, expect everything around modern (postmodern?) business intelligence

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