Computers – Mistakes were made

Recently I wanted to print a document from my Chromebook. Unfortunately my printer is an older Ricoh laser printer that isn’t supported by Chrome OS so I thought I ran out of luck. After some googling I learned about PPD files. According to Wikipedia a PPD file is:

PostScript Printer Description (PPD) files are created by vendors to describe the entire set of features and capabilities available for their PostScript printers.

A PPD also contains the PostScript code (commands) used to invoke features for the print job. As such, PPDs function as drivers for all PostScript printers, by providing a unified interface for the printer’s capabilities and features.

Getting a ppd file for your printer

First of all use your search engine to search for a combination of your printer model or make and “ppd”:

Download the specific PPD file for your printer and start configuring.

Configuration

You will need the IP adress of your printer. If you don’t know this and you’re feeling lazy just download Fing from the Android Play Store, use it to scan your network and determine the IP address. A hostname would be even better since the IP address might change in the future. I just assigned a static address to the printer in my router.

In Chrome OS go to settings > advanced > printing

In the window that appears fill out the necessary fields. Be sure to select Appsocket (TCP/IP)

And click Add

In the next window just select the PPD file you downloaded earlier:

And presto, printing is enabled.

This how-to is based on https://lodge.glasgownet.com/tech/automating-server-startup-with-hp-ilo/ but adapted to iLO 4 (2.73)

1. iLO User

To add a new user, log in to the iLO web interface and select Administration > User administration. For purposes of this how-to a user named ilouser is created

To set up key based authentication, it is wise to set up a user with only the functions you require enabled. Note down the password, but be aware that it is not required after this stage.

2. SSH Key
Once the user has been set up on the iLO, a key-pair with the same username has to be generated. At the command line on a Linux machine, generate the keypair with:

ssh-keygen -f ilouser -C ilouser

ssh-keygen will ask you to enter a passphrase. If you add a passphrase you will have to supply this every time you log in, this is the safest route. Optionally you can skip the passphrase so you can log in directly.

The example above will create a 3072-bit RSA (and SHA256) key, this will result in two files:

pihole:tmp $ ls
ilouser ilouser.pub

ilouser – this private key remains on the source machine
ilouser.pub – this is the public part that will get uploaded to the iLO

Do not change the permission modes on the files, as SSH checks them on use. It will not use files with loose permissions.

3. iLO SSH Key Authentication
Log in to the iLO again, and select the Administration > Security menu. Put a check before the ilouser user and select Authorize new key. A new element will appear in which you have to paste the contents of ilouser.pub. In your bash shell type:

cat ilouser.pub

And copy+paste the entire content as-is in iLO, including the ssh-rsa and ilouser bits. Finish by clicking ‘Import Public Key’

4. Testing Login
Test that the system can log in by specifying the location of the private key (the file without the .pub), the username to login with, and the hostname.

ssh -i /home/username/ilouser ilouser@server.lan

All being well, you will be presented with the iLO SSH interface after a short delay. If you encounter an error involving dispatch_protocol_error, then your iLO firmware should be updated. It will still allow you to execute commands non-interactively though.