Installing a root/CA Certificate on Ubuntu

Given a CA certificate file foo.crt, follow these steps to install it on Ubuntu:

1. Create a directory for extra CA certificates in /usr/share/ca-certificates:

   sudo mkdir /usr/share/ca-certificates/extra
   

2. Copy the CA .crt file to this directory:

   sudo cp foo.crt /usr/share/ca-certificates/extra/foo.crt
   

3. Let Ubuntu add the .crt file’s path relative to /usr/share/ca-certificates to /etc/ca-certificates.conf:

   sudo dpkg-reconfigure ca-certificates
   

   To do this non-interactively, run:

   sudo update-ca-certificates
   

In case of a .pem file on Ubuntu, it must first be converted to a .crt file:

openssl x509 -in foo.pem -inform PEM -out foo.crt