Last night I made the aggravating discovery that cups has gone SSL. The option to have cups protected by SSL is wonderful but I’m not sure that SSL by default is a good thing for printing services. I discovered this because printing from my Apple machines was failing with no log messages from my the Apple machines on my network. At first I thought this might be an IPv6 issue. Using tcpdump I quickly determined that cups on my Mac was not only using IPv6 but that it was using the semi-random “private/temporary” address of my cups server. But continued debugging showed that IPv6 wasn’t the issue, and the private/temporary address wasn’t it either. Disabling Encryption with the:
Did the trick. This is clearly not safe. What would be best would be cutting a certificate for my cups server. That’s problematic because two years from now when the certificate expires, how long will it take me to figure out why printing stops working. Perhaps best would be to encrypt requests that need a password and allow cleartext communications for plain printing.