I don't see a knoppix specific discussion and Debian is the core, so here goes. I have newly installed Knoppix 7 DVD via USB using the universal installer 9.1.1 that I found on the pendrive site. That works great. I have an old but sturdy Brother MFC-420CN printer which works brilliantly with Macs, XP and Windows 7. I got cups started and tried to use various instructions to set up the printer through the KDE Desktop: Applications - Settings - Printing. This failed miserably mainly because I kept getting prompted for ID and password. Nothing I tried worked, including my root account and password. I had better luck finding the printer in CUPS, which located it on the network. There was no install file for my printer so I followed the instructions from Brother and downloaded the cupswrapper debian files. I got a successful report by installing via the desktop package installer. However, it still did not appear in the driver list. I searched all mentioned directories and found mfc files, but no PPD anywhere. Brother mentions getting the PPD from a gz file. But there is no gz file for my printer or most on their site. I have tried other MFC drivers, but nothing gets through to the printer. Print jobs sit in the queue for a few minutes then are reported completed with no actual printing ever having happened. I have tried to log into the cups server to look there, but run into the same password problem. I have a root password and a user password, neither are accepted. In reading other forums I see that I am not alone in having problems with cups, ppds and printer installations. Any suggestions will be appreciated. I am not accustomed to going through torture to initialize a printer. My printer is on my LAN with static ID 192.168.15.3 and as I say, cups finds it no problem when I run the find printer commands.

I assume you've found this page then: http://welcome.solutions.brother.com.../en/index.html As you describe it, there could be an issue with specifying the right path. Go to http://localhost:631/printers and select your printer, then choose "Modify Printer" in the Administration menu and log in. Then choose from "other network printers" the ldp option and fill the connection entry as:
Mind that the "BINARY_P1" part is the path to the printer spool Cups needs to address the printer correctly.

Hello, yes that Brother page is the one and only page to get the drivers and it is the one I used. I will try your patch when I get back after a trip. I will put a comment back after 27 Oct as to whether the BINARY_P1 change makes a difference. Its the only change in process from what I have tried.