PKI Tutorials - Herong's Tutorial Examples - Version 2.01, by Dr. Herong Yang

Adding Security Exception in Firefox 3

This section provides a tutorial example on how to add a security exception in Firefox 3 to continue visiting an HTTPS Web site with an unstrusted certificate.

What should you do when Firefox 3 tells you that "This Connection is Untrusted"? My suggestions is:

  • Check the Web site address to make sure you are not on a phishing site. For example, instead of you entered, which could be a phishing site to steal your private data.
  • Ask Firefox 3 to add an exception to let you continue to use this site.
  • Or ask Firefox to show the certificate received from the site, review the certificate and fix the problem.

Here is what I did to add a security exception to pass the error page:

1. Open Firefox 3 to visit to again and wait for the error page.

2. Click the link "I Understand the Risks". Firefox 3 displays more warning messages:

If you understand what's going on, you can tell Firefox to start
trusting this site's identification. Even if you trust the site,
this error could mean that someone is tampering with your connection.

Don't add an exception unless you know there's good reason why this
site doesn't use trusted identification.

[ Add Exception... ]

3. Click the "Add Exception" button. The "Add Security Exception" dialog box shows up:
Add Security Exception - Firefox 3

4. Read messages on the dialog box carefully:

You are about to override how Firefox identifies this site.
Legitimate banks, stores, and other public sites will not ask
to do this.

Server Location:

Certificate Status - This site attempts to identify itself with
invalid information.

Unknown Identity - Certificate is not trusted, because it hasn't
been verified by a recognized authority.

[ ] Permanently store this exception

5. Click the "Confirm Security Exception" button. The Yahoo login page shows up.

I could continue to login to my Yahoo account and access my email box if I want to, because I can trust the Yahoo site.

Note that I left the "Permanently store this exception" checkbox unchecked, because I don't want Firefox to remember this exception. When I close Firefox and open it to visit, I want to see the error page again.

Table of Contents

 About This Book

 Introduction of PKI (Public Key Infrastructure)

 Introduction of HTTPS (Hypertext Transfer Protocol Secure)

 Using HTTPS with IE (Internet Explorer) 8

Using HTTPS with Firefox 3

 Visiting "https" Web Site with Firefox 3

 Viewing Server Certificate Details in Firefox 3

 Viewing Server Certificate Path in Firefox 3

 Exporting Server Certificate to File in Firefox 3

 Viewing Pre-Installed Certificates in Firefox 3

 Listing of Trusted Root CA in Firefox 3

 Exporting Certificate to File from Firefox 3

 Deleting Root CA Certificates from Firefox 3

 Firefox 3 Displaying Certificate Error Page

Adding Security Exception in Firefox 3

 Failing to Import Root CA Certificates to Firefox 3

 Certificate Trust Settings in Firefox 3

 Perl Scripts Communicating with HTTPS Servers

 PHP Scripts Communicating with HTTPS Servers

 Java Programs Communicating with HTTPS Servers

 Certificate Stores and Certificate Console

 .NET Programs Communicating with HTTPS Servers - Root CA Offering Free Certificates

 PKI CA Administration - Issuing Certificates

 Digital Signature - Microsoft Word 2007

 Digital Signature - 3

 S/MIME and Email Security

 PKI (Public Key Infrastructure) Terminology


 Printable Copy - PDF Version

Adding Security Exception in Firefox 3 - Updated in 2015, by Dr. Herong Yang