rundll32 printui.dll,PrintUIEntry to map network printers

Have you ever used rundll32 printui.dll,PrintUIEntry to map a network printer on a computer? This command can map a printer for every user and can also be used to remove that same mapping. When you think about it, this behavior is a little odd.

I say that because mapping printers is a user profile based action. If you want a printer to show up for everyone, you have to install it on the computer directly. But somehow this command gets around that.

I was writing a DSC component that used this command and I ran into an issue trying to verify a printer was mapped. CIM_Printer and Win32_Printer could not find the printer when ran in the context of DSC. I suspect that the system account can't see the printer. Once a user is logged in, the connection to that printer is established. I had to find another way to identify these mapped printers.

My first thought was to fire up the Sysinternals procmon.exe tool. Even after filtering it down to just rundll32 related activity, nothing jumped out to me. So I started searching the registry. It didn't take long and I found what I was looking for.

"HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Print\Connections"

That registry location contains the list of printer connections that should be mapped for each user. Those printers are kept separate from the locally installed printers on the system. I started checking this location and everything started working for me.

If you came here trying to map a printer in this way, here are the commands that I used

$path = "\\server\printer name"

# Map a printer
rundll32 printui.dll,PrintUIEntry /ga /n$path 

# remove the printer
rundll32 printui.dll,PrintUIEntry /gd /n$path

# list printer connections
rundll32 printui.dll,PrintUIEntry /ge

KevMar_TcpPrinter v1.0.2

I just pushed an update to my TcpPrinter resource that can now handle basic driver installations. You can optionally provide a path to the inf files needed for the installation. The resource will try and use those if the driver does not exist.

There will be some limitations to this approach but I felt it was important to provide this option. For now, make sure the files are on the target system. You may have to use another resource to copy those files to the target.

Another change in this release is that Ensure="Absent" will try and remove the port and driver if they are not in use anymore. Should help to keep the system a little cleaner. I did add the requirement that the DriverInf property should be defined for it to remove a driver. This assumes that you installed the driver with this resource and can easily add it again. I also wanted to avoid removing any of the built in drivers.

Changes in v1.0.2
  Added DriverInf property
    Allows you to provide the location to the driver's inf file to be used during printer installation
  Modified Ensure="Absent"
    Will remove the printer port if the removed printer was the last one using it
    Will remove the driver only if the DriverInf is defined and the removed printer was the last one using it

https://github.com/kmarquette/Powershell

DSC Resource: KevMar_MapPrinter

Last week I put together a resource for adding TCP printers with Desired State Configuration. After I finished that one, I knew I needed to create another one that loads printers from a print server. They hand in hand even if they have different use cases. I can see using TcpPrinter for a print server and MapPrinter for a terminal server.

This one turned out to be much simpler to put together. I may end up doing a more detailed write up in the future just to show how easy it can be to create a DSC resource. Take a look at how simple the config looks for MapPrinter.

 
MapPrinter NetworkPrinter
       {
            Path = '\\server\EpsonPrinter'            
       }

It does not get much simpler than that. And removing a printer mapped this way is just as easy.

MapPrinter NetworkPrinter
       {
            Path   =  '\\server\EpsonPrinter'            
            Ensure = "Absent"
       }

This will map this printer for every user on the system. There is no way to target just a user with the method that I used. To correctly remove a printer mapped this way, it is best to use the DSC resource to do so. If you have to remove it by hand, here is the command that does the magic.

$path = "\\server\EpsonPrinter"
rundll32 printui.dll,PrintUIEntry /gd /n$path

It feels like the printer is slow to show up the first time this is ran. Restarting the spooler speeds up the process. I don't think the spooler immediately sees the changes.

The KevMar_MapPrinter was added to my other module that I have up on https://github.com/kmarquette/Powershell