I just installed Arch Linux recently and have noticed some odd behavior with the network printer (a Samsung C1860FW model). I have CUPS connected to the printer with IPP and am using a PPD from FooMatic.
Whenever I log in or plug in a flash drive or a USB device, the printer wakes up. Nothing prints, but the printer's touchscreen comes on and it warms up and prepares to print, the same as if I had pressed the power button to wake it up from sleep mode. I changed CUPS logging to debug level and run
udisksctl monitor but nothing relevant shows up. However, logging into the console doesn't trigger this; only logging into Plasma. (I don't have any other desktops installed.)
This happens when I plug devices into the PC (back or front ports doesn't seem to matter).
The PC is connected with Ethernet/CAT5e; printer with WiFi. Both are connected directly to the gateway, there's a switch connected too but it's not in use.
The printer includes the "SyncThru Web Service." I can change the length of time that the printer stays warmed up but not what actions cause it to wake up.
EDIT: Using Wireshark, the packets are going to port 9400 TCP, which apparently means the TWAIN protocol on Samsung devices, so this has something to do with scanning. (I have it connected as a network scanner too.)
EDIT 2: Using NetHogs, I found that
colord-sane is sending packets. I also found this but there were no relevant answers as to how to disable this behavior. I will investigate further...
EDIT 4: I renamed the colord service file. Fixed for now.