qubes-doc/user/advanced-configuration/config-files.md

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Configuration Files

Qubes-specific VM config files

These files are placed in /rw, which survives a VM restart. That way, they can be used to customize a single VM instead of all VMs based on the same template. The scripts here all run as root.

• /rw/config/rc.local - script runs at VM startup. Good place to change some service settings, replace config files with its copy stored in /rw/config, etc. Example usage:

  # Store bluetooth keys in /rw to keep them across VM restarts
  rm -rf /var/lib/bluetooth 
  ln -s /rw/config/var-lib-bluetooth /var/lib/bluetooth
  

  # Add entry to /etc/hosts
  echo '127.0.0.1 example.com >> /etc/hosts
  

• /rw/config/qubes-ip-change-hook - script runs in NetVM after every external IP change and on "hardware" link status change.

• In ProxyVMs (or AppVMs with qubes-firewall service enabled), scripts placed in the following directories will be executed in the listed order followed by qubes-firewall-user-script after each firewall update. Good place to write own custom firewall rules.

  /etc/qubes/qubes-firewall.d
  /rw/config/qubes-firewall.d
  /rw/config/qubes-firewall-user-script
  

• /rw/config/suspend-module-blacklist - list of modules (one per line) to be unloaded before system goes to sleep. The file is used only in a VM with PCI devices attached. Intended for use with problematic device drivers.

• In NetVMs/ProxyVMs, scripts placed in /rw/config/network-hooks.d will be ran when configuring Qubes interfaces. For each script, the command, vif, vif_type and ip is passed as arguments (see /etc/xen/scripts/vif-route-qubes). For example, consider an PV AppVM work with IP 10.137.0.100 and sys-firewall as NetVM. Assuming it's Xen domain id is arbitrary 12 then, the following script located at /rw/config/network-hooks.d/hook-100.sh in sys-firewall:

  #!/bin/bash
  
  command="$1"
  vif="$2"
  vif_type="$3"
  ip="$4"
  
  if [ "$ip" == '10.137.0.100' ]; then
      case "$command" in
          online)
              ip route add 192.168.0.100 via 10.137.0.100
              ;;
          offline)
              ip route del 192.168.0.100
              ;;
      esac
  fi
  

  will be executed with arguments online vif12.0 vif 10.137.0.100 when starting work. Please note that in case of HVM, the script will be called twice - once with vif_type vif, then with vif_type vif_ioemu (and different interface names). As long as the ioemu interface exists, it should be preferred (up to the hook script). When VM decide to use PV interface (vif_type vif), the ioemu one will be unplugged.

Note that scripts need to be executable (chmod +x) to be used.

Also, take a look at bind-dirs for instructions on how to easily modify arbitrary system files in an AppVM and have those changes persist.

GUI and audio configuration in dom0

The GUI configuration file /etc/qubes/guid.conf in one of a few not managed by qubes-prefs or the Qubes Manager tool. Sample config (included in default installation):

# Sample configuration file for Qubes GUI daemon
#  For syntax go http://www.hyperrealm.com/libconfig/libconfig_manual.html

global: {
  # default values
  #allow_fullscreen = false;
  #allow_utf8_titles = false;
  #secure_copy_sequence = "Ctrl-Shift-c";
  #secure_paste_sequence = "Ctrl-Shift-v";
  #windows_count_limit = 500;
  #audio_low_latency = false;
};

# most of setting can be set per-VM basis

VM: {
  work: {
    #allow_utf8_titles = true;
  };
  video-vm: {
    #allow_fullscreen = true;
  };
};

Currently supported settings:

• allow_fullscreen - allow VM to request its windows to go fullscreen (without any colorful frame).

  Note: Regardless of this setting, you can always put a window into fullscreen mode in Xfce4 using the trusted window manager by right-clicking on a window's title bar and selecting "Fullscreen". This functionality should still be considered safe, since a VM window still can't voluntarily enter fullscreen mode. The user must select this option from the trusted window manager in dom0. To exit fullscreen mode from here, press alt + space to bring up the title bar menu again, then select "Leave Fullscreen".

• allow_utf8_titles - allow the use of UTF-8 in window titles; otherwise, non-ASCII characters are replaced by an underscore.

• secure_copy_sequence and secure_paste_sequence - key sequences used to trigger secure copy and paste.

• windows_count_limit - limit on concurrent windows.

• audio_low_latency - force low-latency audio mode (about 40ms compared to 200-500ms by default). Note that this will cause much higher CPU usage in dom0.