# on a successful verification
# 注意需要指定端口，如果是https協議，默認端口也需要指定端口443
$ openssl s_client -quiet -connect jvt.me:443
depth=2 O = Digital Signature Trust Co., CN = DST Root CA X3
verify return:1
depth=1 C = US, O = Let's Encrypt, CN = Let's Encrypt Authority X3
verify return:1
depth=0 CN = jamietanna.co.uk
verify return:1
# on an unsuccessful verification
$ openssl s_client -quiet -connect keystore.openbanking.org.uk:443
depth=2 C = GB, O = OpenBanking, CN = OpenBanking Root CA
verify error:num=19:self signed certificate in certificate chain
verify return:1
depth=2 C = GB, O = OpenBanking, CN = OpenBanking Root CA
verify return:1
depth=1 C = GB, O = OpenBanking, CN = OpenBanking Issuing CA
verify return:1
depth=0 C = GB, O = OpenBanking, OU = Open Banking Directory, CN = keystore
verify return:1
read:errno=104
# for an expired cert
$ openssl s_client -quiet -connect expired.badssl.com:443
depth=2 C = GB, ST = Greater Manchester, L = Salford, O = COMODO CA Limited, CN = COMODO RSA Certification Authority
verify error:num=20:unable to get local issuer certificate
verify return:1
depth=1 C = GB, ST = Greater Manchester, L = Salford, O = COMODO CA Limited, CN = COMODO RSA Domain Validation Secure Server CA
verify return:1
depth=0 OU = Domain Control Validated, OU = PositiveSSL Wildcard, CN = *.badssl.com
verify error:num=10:certificate has expired
notAfter=Apr 12 23:59:59 2015 GMT
verify return:1
depth=0 OU = Domain Control Validated, OU = PositiveSSL Wildcard, CN = *.badssl.com
notAfter=Apr 12 23:59:59 2015 GMT
常見錯誤 https://www.jb51.net/LINUXjishu/287588.html
命令行添加證書 https://manuals.gfi.com/en/kerio/connect/content/server-configuration/ssl-certificates/adding-trusted-root-certificates-to-the-server-1605.html