On 11/11/19 2:02 PM, Kent West wrote:
What I mean more specifically is, when I go into the CUPS web
interface to set up a new printer, and go through the Add Printer
stuff, and select "Other Network Printers" / "Internet Printing
Protocol (ipps)" (because the printer is on a different subnet/virtual
LAN and therefore doesn't get autodetected via Bonjour/mDNS/DNS-SD),
and then on the next screen enter the IP address of the printer, I
would have expected the IPP protocol to then handle the rest of the
printer setup, but instead I'm still asked for the printer name and
printer model (although I just now noticed that what is currently
selected (I'm not sure it was when I started this email) is
"{current_make_and_model} - IPP Everywhere" - perhaps this option is
doing what I was expecting?).
(If I select that IPP Everywhere option, the next screen errors out
saying "Unable to open PPD file: Missing asterisk in column 1", so I
suspect that option is not doing what I was expecting.)
Then again, maybe it does. After that failure, I went back into printer
management and found that a printer had been created, that appeared
broken. So I deleted it, and just to be thorough, I repeated the process
above, again (only this time choosing "Internet Printing Protocol
(http)". This time I did not get the error reported above, and the
printer list now shows what looks to be a properly-installed printer,
with an auto-populated model number (so apparently two-way IPP
communication is working).
I did a test print which was successful.
So then I deleted that printer, and again added the printer, this time
going back to using "Internet Printer Protocol (ipps)", and again I got
the failure error message. Apparently there IS a difference between
these four protocols:
Internet Printing Protocol (http)
Internet Printing Protocol (https)
Internet Printing Protocol (ipp)
Internet Printing Protocol (ipps)
even though "ls -l /usr/lib/cups/backend" all show them to all be or
symlink to the same file. So I'm left with my original question from my
earlier-today post/question: What's the difference between these four
protocols, and why would I select one over the others?
Thanks!
--
Kent
