$ gnutls-cli -p https riseup.net | egrep 'subject|trust'
*** Fatal error: Error in the certificate.
*** handshake has failed: Error in the certificate.
 - subject `CN=riseup.net,O=OpenDNS\, Inc.,L=San Francisco,ST=California,C=US', issuer `O=Cisco,CN=Cisco Umbrella Secondary SubCA nyc-SG', serial 0x59f33761, RSA key 2048 bits, signed using RSA-SHA256, activated `2017-10-25 13:30:44 UTC', expires `2017-10-30 13:30:44 UTC', key-ID `sha256:1e1e576cf8b15dcf29f521ae85fd3b5ed69991fc6d60ab3bcd32e9a79da15b7e'
 - subject `O=Cisco,CN=Cisco Umbrella Secondary SubCA nyc-SG', issuer `O=Cisco,CN=Cisco Umbrella Primary SubCA', serial 0x20256f02f61f42e49612432d95478bbe, RSA key 2048 bits, signed using RSA-SHA256, activated `2017-10-26 10:58:35 UTC', expires `2017-11-06 10:58:35 UTC', key-ID `sha256:1e1e576cf8b15dcf29f521ae85fd3b5ed69991fc6d60ab3bcd32e9a79da15b7e'
 - subject `O=Cisco,CN=Cisco Umbrella Primary SubCA', issuer `CN=Cisco Umbrella Root CA,O=Cisco', serial 0x044863ab1546458d72, RSA key 2048 bits, signed using RSA-SHA256, activated `2016-06-28 15:40:11 UTC', expires `2021-06-28 15:40:11 UTC', key-ID `sha256:41f882a0e6e7b9ca94aded115daca0b0cfaa204d9b14df9181c1100ff8a4af6b'
- Status: The certificate is NOT trusted. The certificate issuer is unknown.