Firefox 33 no longer supports keys less than 1024 bits
You can fix this right from Webmin if you:
ssl=0in
/etc/webmin/miniserv.confand restart webmin with
/etc/init.d/webmin restartor
Webmin -> Webmin Configuration -> SSL Encryption -> Self Signed CertificateFill in the form (or leave the defaults) and then click the Create Now button. If you temporarily disabled ssl enable it with
ssl=1in
/etc/webmin/miniserv.confand restart webmin with
/etc/init.d/webmin restartThis will update your self-signed certificate for Webmin and you will now be able to access the page from Firefox 33 (With the usual browser warning about an untrusted connection).