qubes-doc/customization/dispvm-customization.md

---
layout: doc
title: Disposable VM Customization
permalink: /doc/dispvm-customization/
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---

Disposable VM Customization
============================

Qubes 4.0
----------

Disposable VM in Qubes 4.0 can be based on any template-based AppVM. You can also choose to use different AppVMs for different Disposable VMs. To prepare AppVM to be a base for Disposable VM, you need to set `template_for_dispvms` property, for example:

    [user@dom0 ~]$ qvm-prefs fedora-26-dvm template_for_dispvms True

Additionally, if you want to have menu entries for starting applications in Disposable VM based on this AppVM (instead of in the AppVM itself), you can achieve it with `appmenus-dispvm` feature:

    [user@dom0 ~]$ qvm-features fedora-26-dvm appmenus-dispvm 1

### Creating new Disposable VM base AppVM ###

You may want to use multiple AppVMs for different Disposable VMs. To create new one, lets say `custom-dvm`, based on `debian-9` template, use following commands:

    [user@dom0 ~]$ qvm-create --template debian-9 --label red custom-dvm
    [user@dom0 ~]$ qvm-prefs custom-dvm template_for_dispvms True
    [user@dom0 ~]$ qvm-features custom-dvm appmenus-dispvm 1

Additionally you may want to set it as default Disposable VM base:

    [user@dom0 ~]$ qubes-prefs default_dispvm custom-dvm

The above default is used whenever a qube request starting a new Disposable VM and do not specify which one (for example `qvm-open-in-dvm` tool). This can be also set in qube settings and will affect service calls from that qube. See [qrexec documentation](/doc/qrexec3/#extra-keywords-available-in-qubes-40-and-later) for details.

If you wish to use the `fedora-minimal` template as a DVM Template, see the "DVM Template" use case under [fedora-minimal customization](/doc/templates/fedora-minimal/#customization).


### Customization of Disposable VM ###

It is possible to change the settings for each new Disposable VM (DispVM). This can be done by customizing the base AppVM:

1.  Start a terminal in the `fedora-26-dvm` qube (or another base for DispVM) by running the following command in a dom0 terminal. (If a qube have `appmenus-dispvm` feature set, there is no menu entry to start applications directly in it, instead of Disposable VM based on it).

        [user@dom0 ~]$ qvm-run -a fedora-26-dvm gnome-terminal

2.  Change the qube's settings and/or applications, as desired. Some examples of changes you may want to make include:
    -   Changing Firefox's default startup settings and homepage.
    -   Changing Nautilus' default file preview settings.
    -   Changing the DispVM's default NetVM. For example, you may wish to set the NetVM to "none." Then, whenever you start a new DispVM, you can choose your desired ProxyVM manually (by changing the newly-started DipsVMs settings). This is useful if you sometimes wish to use a DispVM with a TorVM, for example. It is also useful if you sometimes wish to open untrusted files in a network-disconnected DispVM.

4.  Shutdown the qube (either by `poweroff` from qube's terminal, or `qvm-shutdown` from dom0 terminal).
        

### Adding programs to Disposable VM Application Menu ###

For added convenience, arbitrary programs can be added to the Application Menu of the Disposable VM. 

In order to do that, select "Qube settings" entry in selected base AppVM, go to "Applications" tab and select desired applications as for any other qube.

Note that currently only applications whose main process keeps running until you close the application (i.e. do not start a background process instead) will work. One of known examples of incompatible applications is GNOME Terminal (shown on the list as "Terminal"). Choose different terminal emulator (like XTerm) instead.

Qubes 3.2
----------

### Changing the DVM Template ###

You may want to use a non-default template the [DVM Template](/doc/glossary/#dvm-template). One example is to use a less-trusted template with some less trusted, third-party, often unsigned, applications installed, such as e.g. third-party printer drivers.

In order to regenerate the Disposable VM "snapshot" (called 'savefile' on Qubes) one can use the following command in Dom0:

    [user@dom0 ~]$ qvm-create-default-dvm <custom-template-name>

This would create a new Disposable VM savefile based on the custom template.
For example `<custom-template-name>` could be the name of the existing `debian-8` vm, which creates the disposable vm `debain-8-dvm`.
Now, whenever one opens a file (from any AppVM) in a Disposable VM, a Disposable VM based on this template will be used.

One can easily verify if the new Disposable VM template is indeed based on a custom template (in the example below the template called "f17-yellow" was used as a basis for the Disposable VM):


    [user@dom0 ~]$ ll /var/lib/qubes/dvmdata/
    total 0
    lrwxrwxrwx 1 user user 45 Mar 11 13:59 default_dvm.conf -> /var/lib/qubes/appvms/f17-yellow-dvm/dvm.conf
    lrwxrwxrwx 1 user user 49 Mar 11 13:59 default_savefile -> /var/lib/qubes/appvms/f17-yellow-dvm/dvm-savefile
    lrwxrwxrwx 1 user user 47 Mar 11 13:59 savefile_root -> /var/lib/qubes/vm-templates/f17-yellow/root.img

If you wish to use the `fedora-minimal` template as a DVM Template, see the "DVM Template" use case under [fedora-minimal customization](/doc/templates/fedora-minimal/#customization).


### Customization of Disposable VM ###

It is possible to change the settings of each new Disposable VM (DispVM). This can be done by customizing the DispVM template:

1.  Start a terminal in the `fedora-23-dvm` TemplateVM by running the following command in a dom0 terminal. (By default, this TemplateVM is not shown in Qubes VM Manager. However, it can be shown by selecting "Show/Hide internal VMs.")


        [user@dom0 ~]$ qvm-run -a fedora-23-dvm gnome-terminal

2.  Change the VM's settings and/or applications, as desired. Note that currently Qubes supports exactly one DispVM template, so any changes you make here will affect all DispVMs. Some examples of changes you may want to make include:
    -   Changing Firefox's default startup settings and homepage.
    -   Changing Nautilus' default file preview settings.
    -   Changing the DispVM's default NetVM. For example, you may wish to set the NetVM to "none." Then, whenever you start a new DispVM, you can choose your desired ProxyVM manually (by changing the newly-started DispVM's settings). This is useful if you sometimes wish to use a DispVM with a TorVM, for example. It is also useful if you sometimes wish to open untrusted files in a network-disconnected DispVM.

3.  Create an empty `/home/user/.qubes-dispvm-customized` file in the VM (not in dom0):


        [user@fedora-23-dvm ~]$ touch /home/user/.qubes-dispvm-customized

4.  Shutdown the VM (either by `poweroff` from VM terminal, or `qvm-shutdown` from dom0 terminal).
5.  Regenerate the DispVM template using the default template:

        [user@dom0 ~]$ qvm-create-default-dvm --default-template
        
    Or, if you're [using a non-default template](#changing-the-dvm-template), regenerate the DispVM using your custom template:
    
        [user@dom0 ~]$ qvm-create-default-dvm <custom-template-name>


**Note:** All of the above requires at least qubes-core-vm \>= 2.1.2 installed in template.


### Adding arbitrary programs to Disposable VM Application Menu ###

For added convenience, arbitrary programs can be added to the Application Menu of the Disposable VM. In order to do that create (e.g.) `arbitrary.desktop` file in `/usr/local/share/applications` in Dom0. That file will point to the desired program. Use the following template for the file:

    [Desktop Entry]
    Version=1.0
    Type=Application
    Exec=sh -c 'echo arbitrary | /usr/lib/qubes/qfile-daemon-dvm qubes.VMShell dom0 DEFAULT red'
    Icon=dispvm-red
    Terminal=false
    Name=DispVM: Arbitrary Name
    GenericName=DispVM: Arbitrary Generic Name
    StartupNotify=false
    Categories=Network;X-Qubes-VM;

Next, the `/etc/xdg/menus/applications-merged/qubes-dispvm.menu` file has to be modified so that it points to the newly-created .desktop file. (If you use i3 you can skip this step; the shortcut gets added to dmenu automatically.)

Add a `<Filename>arbitrary.desktop</Filename>` line so that your modified file looks like this:

    <Include>
    <Filename>qubes-dispvm-firefox.desktop</Filename>
    <Filename>qubes-dispvm-xterm.desktop</Filename>
    <Filename>arbitrary.desktop</Filename>
    </Include>

After saving the changes the new shortcut should appear in the Disposable VM Applications menu.