Print Service
From OpenFSG
The Printing Service
The printing service is provided by the p910nd daemon. It is a very lightweight daemon, that merely forwards all bytes that arrive at an IP port to a /dev/lp device, i.e. no spooling or other sophisticated print services are provided. In particular, no authentication takes place, i.e. everyone that can access the particular IP port is able to print. This is also the reason, why this service is by default not available via the WAN port, but needs to be enabled via the command line.
Each time, a printer is connected to a USB port, the hotplugging service of the Linux kernel is used to start a p910nd daemon for that USB port. It is hardcoded into the Linux kernel that the hotplugging service calls /sbin/hotplug. In our devices, this is a binary program that does the right actions for the different classes of USB devices, e.g. a mass storage device is automatically mounted. If a USB printer is connected, the first printer is connected to port 9100, the second to port 9101 and so on.
The binary of p910nd can be found in file /sbin/p910nd. Note that once p910nd is started, it changes in its process name the "n" to the port to which it listens, i.e. in the list of processes it appears as /sbin/p9100, /sbin/p9101 and so on.
- As of firmware 4.3.8, p910nd Version 0.7 is installed. That version supports in principle bidirectional copying; however, according to the Firmware changelog this is disabled, because it makes problems.
- The newest version is 0.91, as you can see on http://etherboot.sourceforge.net/p910nd/
- Some more info about in this topic: NDP print server functionality.... p9100nd.
