Openssl: show serial-# and issuer
openssl s_client -connect cipv6.de:443 2>&1|openssl x509 -noout -serial -issuer serial=03839493CC06B9487E59A519EEDABC5FAE36 issuer=C = US, O = Let’s Encrypt, CN = Let’s Encrypt Authority X3
openssl s_client -connect cipv6.de:443 2>&1|openssl x509 -noout -serial -issuer serial=03839493CC06B9487E59A519EEDABC5FAE36 issuer=C = US, O = Let’s Encrypt, CN = Let’s Encrypt Authority X3