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pikvm/pages/cookbook.md

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Some random and useful recipes

Take a HDMI screenshot via console on Pi-KVM

# curl --unix-socket /run/kvmd/ustreamer.sock http://localhost/snapshot -o screen.jpg

Get installed KVMD version via console

# pacman -Q | grep kvmd

Upload .ISO images manually

Specifically to v2.

  1. Remount internal storage to rw (read-write):
    # kvmd-helper-otgmsd-remount rw
    
  2. Upload the .ISO image(s) to /var/lib/kvmd/msd/images via scp or similar.
  3. Create an empty file in /var/lib/kvmd/msd/meta/ with the exact name (case sensitive!) of the uploaded image. This will indicate Pi-KVM that the uploaded image is okay and can be used. For example:
    /var/lib/kvmd/msd/meta/ubuntu-18.04.4-desktop-amd64.iso.complete
    
  4. Remount internal storage back to ro (read-only):
    # kvmd-helper-otgmsd-remount ro
    

Enable Serial-over-USB connection

Specifically to v2. This can be used for terminal access from the managed server to the Pi-KVM, or for any other purpose that requires a serial connection. In the last case, you only need to perform step 1 and reboot.

  1. Edit /etc/kvmd/override.yaml (remove {} if this your first configuration entry) and add these lines:
    otg:
        devices:
            serial:
                enabled: true
    
  2. Run the following command:
    # echo ttyGS0 >> /etc/securetty
    
  3. Create the directory /etc/systemd/system/getty@ttyGS0.service.d and add a file file named ttyGS0.override into it. Afterwards edit the file and copy this into it:
    [Service]
    TTYReset=no
    TTYVHangup=no
    TTYVTDisallocate=no
    
  4. Run these comands:
    # systemctl enable getty@ttyGS0.service
    # reboot
    
  5. Once Pi-KVM is rebooted you will have access to a virtual serial port on the server that the USB is connected to. Use mingetty, screen, putty, or something like this to access the kvm from the server. The port is called /dev/ttyAMA0.

Enable Ethernet-over-USB network

Specifically to v2. When combined with configuring a DNS server, FTP, or SMB (for example), this is a powerful way to extend the capabilities of Pi-KVM.

  1. Edit /etc/kvmd/override.yaml (remove {} if this your first configuration entry) and add these lines:
    otg:
        devices:
            ethernet:
                enabled: true
                driver: ecm
                host_mac: 48:6f:73:74:50:43
                kvm_mac: 42:61:64:55:53:42
    
    The host_mac address will be used on the server's network interface. The kvm_mac means the address that will be assigned to the local interface on the Pi-KVM. The KVM interface will be called usb0.r's network interface. If the host_mac or kvm_mac is not specified, a random value will be used. The driver parameter means the protocol that will be used for the USB network. The default value is ecm so it can be passed it this example. Other possible values are eem, ncm and rndis.
  2. Perform reboot.

When this feature is activated, the Pi-KVM interface and other ports will be available to the host. Use iptables for restrictions.

Adding extra Mass Storage Drives

Specifically to v2. By default, Pi-KVM creates only one drive for Mass Storage emulation. However, you can create additional drives and manage them manually via the terminal. This is useful if you want to boot the server from a ISO CD (specified in the web interface), then connect a virtual flash drive to the server and download some files from to Pi-KVM from it.

The presence of an additional Mass Storage device should not interfere with the download, but for reasons of compatibility paranoia, this is disabled by default. We recommend setting up the drives in advance, making sure that booting from the ISO CD is still working, and then using the drives as needed.

How to enable extra drives:

  1. Switch the root filesystem to rw mode.
  2. Edit /etc/kvmd/override.yaml (remove {} if this your first configuration entry) and add these lines:
    otg:
        devices:
            drives:
                enabled: true  # Set it to true to enable
                count: 1  # +1 drive, default value
                default:  # Default configuration for the all extra drives
                    cdrom: false  # Defaut value (false for the generic flash drive)
                    rw: false # Read-only by default
    
    If you specify count: N, you will create N additional drives configured the same way, as described in the default section.
  3. Reboot.

How to create RW flash drive:

  1. Switch the root filesystem to rw mode:
    # rw
    
  2. Create the empty image file of the desire size (1Gb in this example.
    # dd if=/dev/zero of=/root/flash.img bs=1024
    
  3. Connect it to the drive 1:
    # kvmd-otgmsd -i 1 --set-rw=1 --set-cdrom=0 --set-image=/root/flash.img
    
    After that you will have access to the flash drive from the server.
    :exlcamation: Drive 0 represents a drive that is controlled via a web interface and API. Don't use it with kvmd-otgmsd if you don't know exactly what you're doing.
  4. View the driver state:
    # kvmd-otgmsd -i 1
    Image file:  /root/flash.img
    CD-ROM flag: no
    RW flag:     yes
    
  5. To disable the flash drive and view the files on it from the KVM, run:
    # kvmd-otgmsd -i 1 --unlock --eject
    
    This command will interrupt the current IO operation on ALL DRIVES including the one that is managed via the web interface. The same result is achieved by clicking the disable media button in the web interface. Right now, the Linux kernel does not allow to distinguish between internal threads that manage different drives. It is recommended to eject the media when you know that this will not cause problems for the other media.
  6. Don't forget to remount the root filesystem to read-only mode:
    # ro
    
  7. You can download the resulting image via SCP or mount it as a loop device on the Pi-KVM.