bk138/droidVNC-NG

VNC server app for Android that does not require root privileges.

droidVNC-NG

This is an Android VNC server using contemporary Android 5+ APIs. It therefore does not require root access. In reverence to the venerable droid-VNC-server is is called droidVNC-NG.

If you have a general question, it's best to ask in the community chat. If your concern is about a bug or feature request instead, please use the issue tracker.

Features

• Network export of device frame buffer with optional server-side scaling.
• Injection of remote pointer and basic keyboard events.
• Handling of client-to-server text copy & paste. Note that server-to-client copy & paste does not work in a generic way due to Android security restrictions.
• Handling of special keys to trigger 'Recent Apps' overview, Home button, Back button and Power button.
• Android permission handling.
• Screen rotation handling.
• File transfer via the local network, assuming TightVNC viewer for Windows version 1.3.x is used.
• Password protection for secure-in-terms-of-VNC connection.
• Ability to specify the port used.
• Start of background service on device boot.
• Reverse VNC.
• Ability to connect to a UltraVNC-style Mode-2 repeater.
• Functionality to provide default configuration via a JSON file.
• Zeroconf/Bonjour publishing for VNC server auto-discovery.
• Per-client mouse pointers on the controlled device.
• Ability to control a device’s shared screen directly from a web browser by shipping the fabulous noVNC client with the server app. This alleviates the need for a native VNC client.

How to use

1. Install the app from either marketplace.
2. Get it all the permissions required.
3. Set a good password and consider turning the Start on Boot off.
4. Connect to your local Wi-Fi. For accepting a connection your device should be connected to some Local Area Network that you can control, normally it is a router. Connections via data networks (i.e. your mobile provider) are not supported.
5. Click Start and connect to your device.

Keyboard Shortcuts From a VNC Viewer

• Ctrl-Shift-Esc triggers 'Recent Apps' overview
• Home/Pos1 acts as Home button
• End acts as Power button
• Escape acts as Back button

For accepting connections from outside

1. You should allow Port Forwarding in your router's Firewall settings. Login to your router's settings (usually open 192.168.1.1 in your browser, some routers have password written on them).

2. Find Port Forwarding, usually it's somewhere in Network - Firewall - Port Forwards.

3. Create a new rule, this is an example from OpenWRT firmware.

   Name: VNC forwarding

   Protocol: TCP

   Source zone: wan may be "internet", "modem", something that suggests the external source.

   External port: 5900 by default or whatever you specified in the app.

   Destination zone: lan something that suggests local network.

   Internal IP address: your device's local IP address, leaving any is less secure. The device's address may change over time! You can look it up in your routers' connected clients info.

   Internal port: same as external port.

4. Apply the settings, sometimes it requires rebooting a router.

5. Figure out your public adress i.e. https://www.hashemian.com/whoami/.

6. Use this address and port from above to connect to your device.

How to Pre-seed Preferences

DroidVNC-NG can read a JSON file with default settings that apply if settings were not changed by the user. A file named defaults.json needs to created under <external files directory>/Android/data/net.christianbeier.droidvnc_ng/files/ where depending on your device, <external files directory> is something like /storage/emulated/0 if the device shows two external storages or simply /sdcard if the device has one external storage.

An example defaults.json with completely new defaults (not all entries need to be provided) is:

{
    "port": 5901,
    "portReverse": 5555,
    "portRepeater": 5556,
    "scaling": 0.7,
    "viewOnly": false,
    "showPointers": true,
    "fileTransfer": true,
    "password": "supersecure",
    "accessKey": "evenmoresecure",
    "startOnBoot": true,
    "startOnBootDelay": 0
}

Remote Control via the Intent Interface

droidVNC-NG features a remote control interface by means of Intents. This allows starting the VNC server from other apps or on certain events. It is designed to be working with automation apps like MacroDroid, Automate or Tasker as well as to be called from code.

You basically send an explicit Intent to net.christianbeier.droidvnc_ng.MainService with one of the following Actions and associated Extras set:

• net.christianbeier.droidvnc_ng.ACTION_START: Starts the server.

  • net.christianbeier.droidvnc_ng.EXTRA_ACCESS_KEY: Required String Extra containing the remote control interface's access key. You can get/set this from the Admin Panel.
  • net.christianbeier.droidvnc_ng.EXTRA_REQUEST_ID: Optional String Extra containing a unique id for this request. Used to identify the answer from the service.
  • net.christianbeier.droidvnc_ng.EXTRA_PORT: Optional Integer Extra setting the listening port. Set to -1 to disable listening.
  • net.christianbeier.droidvnc_ng.EXTRA_PASSWORD: Optional String Extra containing VNC password.
  • net.christianbeier.droidvnc_ng.EXTRA_SCALING: Optional Float Extra between 0.0 and 1.0 describing the server-side framebuffer scaling.
  • net.christianbeier.droidvnc_ng.EXTRA_VIEW_ONLY: Optional Boolean Extra toggling view-only mode.
  • net.christianbeier.droidvnc_ng.EXTRA_SHOW_POINTERS: Optional Boolean Extra toggling per-client mouse pointers.
  • net.christianbeier.droidvnc_ng.EXTRA_FILE_TRANSFER: Optional Boolean Extra toggling the file transfer feature.
  • net.christianbeier.droidvnc_ng.EXTRA_FALLBACK_SCREEN_CAPTURE: Optional Boolean Extra indicating whether to start with fallback screen capture that does not need a user interaction to start but is slow and needs view-only to be off. Only applicable to Android 10 and newer.

• net.christianbeier.droidvnc_ng.ACTION_CONNECT_REVERSE: Make an outbound connection to a listening viewer.

  • net.christianbeier.droidvnc_ng.EXTRA_ACCESS_KEY: Required String Extra containing the remote control interface's access key. You can get/set this from the Admin Panel.
  • net.christianbeier.droidvnc_ng.EXTRA_REQUEST_ID: Optional String Extra containing a unique id for this request. Used to identify the answer from the service.
  • net.christianbeier.droidvnc_ng.EXTRA_HOST: Required String Extra setting the host to connect to.
  • net.christianbeier.droidvnc_ng.EXTRA_PORT: Optional Integer Extra setting the remote port.
  • net.christianbeier.droidvnc_ng.EXTRA_RECONNECT_TRIES: Optional Integer Extra setting the number of tries reconnecting a once established connection. Needs request id to be set.

• net.christianbeier.droidvnc_ng.ACTION_CONNECT_REPEATER Make an outbound connection to a repeater.

  • net.christianbeier.droidvnc_ng.EXTRA_ACCESS_KEY: Required String Extra containing the remote control interface's access key. You can get/set this from the Admin Panel.
  • net.christianbeier.droidvnc_ng.EXTRA_REQUEST_ID: Optional String Extra containing a unique id for this request. Used to identify the answer from the service.
  • net.christianbeier.droidvnc_ng.EXTRA_HOST: Required String Extra setting the host to connect to.
  • net.christianbeier.droidvnc_ng.EXTRA_PORT: Optional Integer Extra setting the remote port.
  • net.christianbeier.droidvnc_ng.EXTRA_REPEATER_ID: Required String Extra setting the ID on the repeater.
  • net.christianbeier.droidvnc_ng.EXTRA_RECONNECT_TRIES: Optional Integer Extra setting the number of tries reconnecting a once established connection. Needs request id to be set.

• net.christianbeier.droidvnc_ng.ACTION_STOP: Stops the server.

  • net.christianbeier.droidvnc_ng.EXTRA_ACCESS_KEY: Required String Extra containing the remote control interface's access key. You can get/set this from the Admin Panel.
  • net.christianbeier.droidvnc_ng.EXTRA_REQUEST_ID: Optional String Extra containing a unique id for this request. Used to identify the answer from the service.

The service answers with a Broadcast Intent with its Action mirroring your request:

• Action: one of the above Actions you requested
  • net.christianbeier.droidvnc_ng.EXTRA_REQUEST_ID: The request id this answer is for.
  • net.christianbeier.droidvnc_ng.EXTRA_REQUEST_SUCCESS: Boolean Extra describing the outcome of the request.

There is one special case where the service sends a Broadcast Intent with action net.christianbeier.droidvnc_ng.ACTION_STOP without any extras: that is when it is stopped by the system.

Examples

Start a password-protected view-only server on port 5901

Using adb shell am syntax:

adb shell am start-foreground-service \
 -n net.christianbeier.droidvnc_ng/.MainService \
 -a net.christianbeier.droidvnc_ng.ACTION_START \
 --es net.christianbeier.droidvnc_ng.EXTRA_ACCESS_KEY de32550a6efb43f8a5d145e6c07b2cde \
 --es net.christianbeier.droidvnc_ng.EXTRA_REQUEST_ID abc123 \
 --ei net.christianbeier.droidvnc_ng.EXTRA_PORT 5901 \
 --es net.christianbeier.droidvnc_ng.EXTRA_PASSWORD supersecure \
 --ez net.christianbeier.droidvnc_ng.EXTRA_VIEW_ONLY true

Start a server with defaults from Tasker

• Tasker action-category in menu is System -> Send Intent
• In there:
  • Action net.christianbeier.droidvnc_ng.ACTION_START
  • Extra net.christianbeier.droidvnc_ng.EXTRA_ACCESS_KEY:<your api key from DroidVNC-NG start screen>
  • Package net.christianbeier.droidvnc_ng
  • Class net.christianbeier.droidvnc_ng.MainService
  • Target: Service

Start a server with defaults from a Kotlin app

• For apps targeting API level 30+, you'll need to specify that your app is able to see/use droidVNC-NG. You do this by adding the following snippet to your AndroidManifest.xml, right under the <manifest> namepace:

<queries>
    <package android:name="net.christianbeier.droidvnc_ng" />
</queries>

• In your Kotlin code, it's then:

val intent = Intent()
intent.setComponent(ComponentName("net.christianbeier.droidvnc_ng", "net.christianbeier.droidvnc_ng.MainService"))
intent.setAction("net.christianbeier.droidvnc_ng.ACTION_START")
intent.putExtra("net.christianbeier.droidvnc_ng.EXTRA_ACCESS_KEY", "<your api key from DroidVNC-NG start screen>")
startForegroundService(intent)

Make an outbound connection to a listening viewer from the running server

For example from Java code:

See MainActivity.java.

Stop the server again

Using adb shell am syntax again:

adb shell am start-foreground-service \
 -n net.christianbeier.droidvnc_ng/.MainService \
 -a net.christianbeier.droidvnc_ng.ACTION_STOP \
 --es net.christianbeier.droidvnc_ng.EXTRA_ACCESS_KEY de32550a6efb43f8a5d145e6c07b2cde \
 --es net.christianbeier.droidvnc_ng.EXTRA_REQUEST_ID def456

Building

• After cloning the repo, make sure you have the required git submodules set up via git submodule update --init.
• Then simply build via Android Studio or gradlew.

Contributing

Contributions to the project are very welcome and encouraged! They can come in many forms. You can:

• Submit a feature request or bug report as an issue.
• Provide info for issues that require feedback.
• Add features or fix bugs via pull requests. Please note there's a list of issues where contributions are especially welcome. Also, please adhere to the contribution guidelines.

Notes

• Requires at least Android 7.

• Since Android 10, the permission to access the screen contents has to be given on each start and is not saved. You can, however, work around this by installing adb (or simply Android Studio) on a PC, connecting the device running droidVNC-NG to that PC and running adb shell cmd appops set net.christianbeier.droidvnc_ng PROJECT_MEDIA allow once. Alternatively, if using the intent interface, you can also start with net.christianbeier.droidvnc_ng.EXTRA_FALLBACK_SCREEN_CAPTURE set to true.

• You can also use adb to manually give input permission prior to app start via adb shell settings put secure enabled_accessibility_services net.christianbeier.droidvnc_ng/.InputService:$(adb shell settings get secure enabled_accessibility_services).

• If you are getting a black screen in a connected VNC viewer despite having given all permissions, it might be that your device does not support Android's MediaProjection API correctly. To find out, you can try screen recording with another app, ScreenRecorder. If it fails as well, your device most likely does not support screen recording via MediaProjection. This is known to be the case for Android-x86.

• In case you happen to have a board with an Ethernet interface and experience strange hangs during a VNC session, setting the interface to a slower speed might help. This workaround can be applied with mii-tool, for instance.

• If you see a a floating button similar to this on your screen after enabling accessibility, make sure you have the "shortcut" option in accessibility settings turned to off.

• Due to limitations in Android API, secondary displays are not supported.