Printing to Dell 5210n using FTP

My day starting out great at work, printing problems! The dream of every system administrator!

The printer that was acting up was a Dell 5210n, a huge black output monster that generally works extremely well, fast and reliable… except today. After all the standard troubleshooting stuff it still wouldn’t print (and even now it stills refuses). The printing itself works but there is a problem with sending a file from the computer/server to the printer.

Anyway, after an hour or so I decided to portscan it (this is a networked printer). Don’t ask me why I released nmap at it, I just did.

PORT      STATE SERVICE       VERSION
21/tcp    open  ftp           Dell 5210n laser printer ftpd NS.NP.N224
79/tcp    open  finger        Dell Laser Printer 5210n fingerd (Status: No Job Currently Active)
80/tcp    open  http          thttpd
515/tcp   open  printer
631/tcp   open  http          thttpd
5000/tcp  open  upnp          Lexmark C524 Laser Printer UPnP
5001/tcp  open  tcpwrapped
8000/tcp  open  http          thttpd
9100/tcp  open  jetdirect?
10000/tcp open  printer-admin Lexmark printer admin

One of the open ports is TCP port 21 otherwise known as FTP. Strange… so I ftp’d the printer and got a standard prompt.

Next test: uploading a text file Right after the file was uploaded the printer printed the contents of the file! That’s what I call hackable!

The Dell 5210n uses Lexmark internals and apparantly network printing through FTP is one of the features. I had never heard about that feature but it sure is quite nice!