Re: [gentoo-user] upstream broke cups network printing...

[Michael <confabulate@kintzios.com>]

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On Tuesday, 30 June 2020 04:51:03 BST Alan Grimes wrote:
> I was sitting smug and happy thinking I could print from either of my
> computers to the laserjet printer downstairs. So therefore when I need
> to RMA my mobo and need to print out the forms, it doesn't work.
> 
> The sack of crap seems to think it can connect to the printer using:
> 
> Connection:
> dnssd://HP%20Color%20LaserJet%20Pro%20M453-4%20%5B804AC2%5D._ipp._tcp.local/
> ?uuid=beff9c81-55ea-548f-5867-4d44f4da191e

You must have enabled DNSSD (DNS Service Discovery) on your systems, whereby 
DNS packets are sent/received for the purpose of scanning your LAN and 
discovering various network services, including network printers, media 
servers, torrents, etc.

DNSSD is also known as zeroconf and from what I understand was derived from 
Apple's Rendezvous/Bonjour.

The Linux equivalent is Avahi (for server) and nss-mdns (for clients), but 
systemd had to re-engineer everything into its own stack as 'systemd-
resolved', which uses the MSWindows preferred LLMNR.

This is all great if you trust the devices in your LAN not to spoof names and 
intercept your communications, or if LAN side network services pop-up and down 
all the time and you want to have them autoconfigured for use by your LAN 
clients.


> Why in god's name does CPUS think that would work, ofcourse I'm going to
> get: in my error log....
> 
> E [29/Jun/2020:18:39:40 -0400] [CGI] Unable to resolve
> \"dnssd://HP%20Color%20LaserJet%20Pro%20M453-4%20%5B804AC2%5D._ipp._tcp.loca
> l/?uuid=beff9c81-55ea-548f-5867-4d44f4da191e|HP Color LaserJet Pro>
> 
> 
> Naturally, there is no other way to configure this crap with the web
> interface, there are some on-line manpages but they're written in
> moonspeak. =(

You do not need network services autoconfiguration, which is is what the 
dnssd:// URI is trying to achieve, unless printers are added and removed in 
your LAN on a regular basis with different IP addresses, different client PCs 
and devices are connected and disconnected all the time and you expect them 
all to discover network services automatically.

In your case, cups is trying to do what you have specified, by enabling of 
failing to disable a particular USE flag.  If you emerged net-print/cups and 
net-print/cups-filters with USE="zeroconf" enabled you'll get what you got.  
If you disable it you will arrive at a client-printer combo where you have to 
manually configure the connection and driver, at least on the client side.

Since this is an HP printer, I think you'll need the hplip driver, so check 
you have this emerged:

https://wiki.gentoo.org/wiki/HPLIP

Finally, configure your clients to use the printer:

https://wiki.gentoo.org/wiki/Printing


TL;DR:  Stop the cupsd service on your PC.  Open and edit "/etc/cups/
printers.conf" file, changing the DeviceURI:

DeviceURI ipp://12.345.678.9/ipp/print

Where '12.345.678.9' is the statically configured IP address of your printer 
on your LAN, the '.../ipp/' and '.../print' may or may not be needed - try and 
see what you get.

Restart you cupsd and try to print.

Others who use this printer may chime in with specifics.

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