• Download and save the certificate locally to your computer
  • https://manuals.c1.fi/certs/Fennosys-PN-CA.crt

• Open shell

• cd to your firefox profile folder (~/.mozilla/firefox/????????.default*)

• Import CA with certutil cli tool

  $ certutil -d ./  -A -i /usr/local/share/ca-certificates/Fennosys-PN-CA.crt -n "FPN CA" -t "TCu,,"

• The above will require firefox master password (if one is set! - Same which is used for protecting “Logins and Passwords”):

  Enter Password or Pin for "NSS Certificate DB": [enter your ff master passwd]

• Check that our cert was installed OK

  $ certutil -d ./ -L -n "FPN CA" | head

Certificate:
  Data:
      Version: 3 (0x2)
      Serial Number:
          00:c4:ea:e8:f2:05:6c:90:0f
      Signature Algorithm: PKCS #1 SHA-512 With RSA Encryption
      Issuer: "E=-,CN=FPN CA,OU=Fennosys private network,O=Fennosys,L=-,ST=
          -,C=FI"
      Validity:
          Not Before: Tue Aug 14 15:03:54 2018

• All done!