How to make Firefox ignore all SSL certification errors?

Firefox has no such setting.

That's a terribly terse answer, but I'm afraid it's all there is. Firefox usually errs on the side of not letting you view a site at all in case of some problems rather than letting you override it even if you want to.

That said, if you're getting cert waings for everything on a private network, it's almost certain that the local IT group is ruing an SSL interception proxy. You're not going to get to the inteet without accepting their certificate, so here's how you do that:

• Open up the certificate properties for one of the pages you get an error on (after adding the exception in Firefox) by clicking the lock in the address bar, the right arrow, and then "more information".

• In the Security tab, click on View Certificate, and then the Details tab on the new window.

• Under Certificate Hierarchy, examine the name of the topmost certificate. It's probably going to be from a security vendor of some kind like Symantec or Barracuda.

• Click on it, and then go to Export at the bottom.

• Save the file somewhere accessible

• Close the security and certificate windows, and open your Firefox settings (top right hamburger menu, Options)

• Click Advanced on the bottom left, and then click View Certificates

• Click the Authorities tab, and then Import

• Locate the file you just saved

• Accept the waing.

It is very important you don't get into a habit of doing this procedure, and only to do it when you know with COMPLETE certainty that the certificate is legitimate. I caot emphasize this enough - call the IT people and have them verify the name on the certificate if you're even slightly unsure, since now you've just told Firefox to accept any and all certificates that the CA you just imported signed. You will receive no more waings of that sort for this cert. If you import a malicious certificate, you've just shot yourself in the foot.