Where I live we have a corporate firewall which is configured to need a certificate installed on the computers in the house for it to be able to scan for vulnerabilities in secure connections. Without it, a few things won't work as the firewall behaves as a man in the middle, and of course a few websites will deny access to prevent any harm as it looks dangerous.
On Windows, I'd just need to double click the certificate (.p12 extension), insert the password and specify it to be put in "Trusted Root Certification Authorities" and be done with it. On Linux, I haven't had much luck in doing that.
I'm running Arch.