Why can't adb establish a connection all by itself over Wi-Fi?

[Andy Burnelli]

Why can't adb establish a connection all by itself over Wi-Fi?
<https://developer.android.com/studio/command-line/adb>
<https://www.xda-developers.com/install-adb-windows-macos-linux/>
<https://dl.google.com/android/repository/platform-tools_r31.0.3-windows.zip>

Is there a way to establish adb connections to the phone _only_ over Wi-Fi?

Notice there are two questions here, both of which are important to answer:
A. Why?
B. How?

Background:
a. The FOSS Windows android debugger (adb) is kind of flaky (IMHO).
b. For whatever reason, adb sometimes loses the Wi-Fi connection over time.
b. To get the Wi-Fi connection back, you have to re-connect adb over USB.
c. Once you hook up to USB, you can reconnect adb to Android over Wi-Fi.
d. At that point you can disconnect the USB cable & adb Wi-Fi works fine.
Until the next time adb gets flaky on you that is.

The time-honored sequence everyone uses appears to be these steps.
(An assumption is you've connected to adb before; so all setup is done.)
(An assumption is your phone is on your LAN and you know the IP address.)
1. C:\> adb kill-server (optional, but it helps for a starting point)
2. Connect the Android phone to USB (this is the part that's mandatory)
3. Connect to the Android phone over USB.
C:\> adb connect
Or
C:\> adb reconnect
You should see an output of something like:
* daemon not running; starting now at tcp:5037
* daemon started successfully
reconnecting ABCDEFGHIJK [device]
4. C:\> adb tcpip 5555
You want one of these two show up:
restarting in TCP mode port: 5555
Or...
* daemon not running; starting now at tcp:5037
* daemon started successfully
restarting in TCP mode port: 5555
Not this:
* daemon not running; starting now at tcp:5037
* daemon started successfully
error: no devices/emulators found
But you might get this if you started from scratch
* daemon not running; starting now at tcp:5037
* daemon started successfully
error: device unauthorized.
This adb server's $ADB_VENDOR_KEYS is not set
Try 'adb kill-server' if that seems wrong.
Otherwise check for a confirmation dialog on your device.
If you do, just press "Allow" & "Remember" on the phone when it asks.
5. At this point you can disconnect the USB cable (or leave it connected).
6. To connect over Wi-Fi, this always works at this stage in the process.
C:\> adb connect 192.168.0.2
Or, if you're a stickler for details, specifying the port works too.
C:\> adb connect 192.168.0.2:5555
In either case, you want to see this:
connected to 192.168.0.2:5555
7. At this point you are completely connected:
C:\> adb devices
That should output either this (if you left the USB connected).
List of devices attached
ABCDEFGHIJ device
192.168.0.2:5555 device
Or this (if you disconnected the USB already).
List of devices attached
192.168.0.2:5555 device

Note that at this point, the _entire_ phone (even if unrooted) is available
to you over Wi-Fi (to run any and all adb commands you want to run).
<https://www.guru99.com/adb-connect.html>
<https://technastic.com/adb-commands-list-adb-cheat-sheet/>

Notice in the sequence above, which _always_ works, you have to connect to
USB for just a few seconds (in order to establish the adb connection).

Two questions:
*Why can't adb establish a connection all by itself over Wi-Fi?*
*Is there a way to establish adb connections _only_ over Wi-Fi?*
--
BTW, since Android 11 by default will randomize the MAC address on every
single connection (even to the same access point SSID as of Android 12),
you may not want to set your router preferences to "Address Reservation"
but, instead, set the Android phone to "IP Settings === Static", although
there is tons of healthy debate how best to handle randomized MAC addresses
now that both iOS and Android randomize the MAC on every Wi-Fi connection.
<https://i.postimg.cc/Rh87RNrV/macaddr02.jpg> Random MAC on every connect

[Andy Burns]

Andy Burnelli wrote:

> Why can't adb establish a connection all by itself over Wi-Fi?

Are you querying the need for a QR code or pairing-code to be entered? I'd have
though that was a worthwhile security "bump" so that Johnny Hacker can't connect
to your phone without an action from you ...

[Andy Burnelli]

Andy Burns wrote:

>> Why can't adb establish a connection all by itself over Wi-Fi?
>
> Are you querying the need for a QR code or pairing-code to be entered?

Hi Andy,

I think I figured out the problem.

I have never seen a QR code, nor a "pairing code", per se, but of course,
there is a pairing process over USB with adb & the phone that is almost
automatic where it simply asks me to accept it and remember it when the
pairing is initially established.

The problem was that the pairing only happened over USB (not over Wi-Fi).
I could only pair over USB (& then I could use the connection over Wi-Fi).

But I think I solved that problem just now when I tried to test it again.

Today I started fresh by killing adb on Windows (C:\> adb kill-server),
and then I revoked all previous pairing credentials on the phone.
Android 12 Developer options > Revoke USB debugging authorizations

Then I set the Android "Wireless debugging" option on. <== this is new!
Android 12 Developer options > Wireless debugging = On

In addition to these two Android settings which I had already turned on.
Android 12 Developer options > USB debugging = On
Android 12 Developer options > Disable adb authorization timeout = On

So that the Android developer options USB settings looked like this.
<https://i.postimg.cc/9M0Tqzm6/adb01.jpg>

> I'd have
> though that was a worthwhile security "bump" so that Johnny Hacker can't connect
> to your phone without an action from you ...

I just wanted to get rid of the USB cable, that's all.
I think I solved it by setting "Wireless debugging = On" though.

Now I can connect adb to the phone over Wi-Fi _without_ needing the USB
cable in the beginning to establish the initial connection credentials.

1. With the phone _not_ connected over USB but only over Wi-Fi to your LAN.
2. On the PC, kill the adb server (to get to a known good starting point).
C:\> adb kill-server
3. On the phone, wipe out existing credentials (for a good start point).
Android 12 Developer options > Revoke USB debugging authorizations

4. C:\> adb tcpip 5555

error: no devices/emulators found
5. C:\> adb connect 192.168.0.2:5555
failed to authenticate to 192.168.0.2:5555
But, after about 30 seconds, this pops up a query
"Allow USB debugging?" on your phone, and
(o)Always allow from this computer
6. C:\> adb tcpip 5555

restarting in TCP mode port: 5555

7. C:\> adb devices

List of devices attached
192.168.0.2:5555 device

Who knew?
Not me.

In summary, my recent experience has been that...
A. Pairing between adb & the phone "just works" over USB, and,
B. Once paired over USB, then Wi-Fi connections "just work" also, but,
C. You need that extra switch to be on to do the pairing step over Wi-Fi.
Android 12 Developer options > Wireless debugging = On

These are the settings that worked completely over Wi-Fi (no USB needed).
<https://i.postimg.cc/9M0Tqzm6/adb01.jpg>
--
On Usenet, kind hearted people try to help each other all day every day.

[Andy Burnelli]

Andy Burnelli wrote:

>> Are you querying the need for a QR code or pairing-code to be entered?
>

>> Then I set the Android "Wireless debugging" option on. <== this is new!
> Android 12 Developer options > Wireless debugging = On

> So that the Android developer options USB settings looked like this.
> <https://i.postimg.cc/9M0Tqzm6/adb01.jpg>

I admit I had never seen this new QR code option Andy Burns asked about.
<https://developer.android.com/studio/images/run/adb_wifi-wireless_debugging.png>
Nor have I ever needed to use a six-digit "pairing code" Andy Burns spoke
about. Up until now, the connection did all the work for me without either.

That's because for Android 10 and lower, the USB cable pairing was required
(even when connecting Android to the Windows PC over Wi-Fi).
<https://developer.android.com/studio/command-line/adb#wireless>

To sharpen the saw (aka to learn more about any problem set you encounter),
I looked up what the _new_ option of "wireless debugging" does with adb.
*How To Connect Wireless Debugging From Developer Options*
<https://youtu.be/ElahzmTPCYE>

From that video I realized you need to both turn on and long press the
Android ADB wireless-debugging option in order to even _see_ the QR-code
options Andy Burns was asking about, which is why I had never seen them.

While I've been using adb in a rudimentary fashion for years, this
"wireless debugging" option is apparently new with Android 11 and up.
*Android 11 DP2: Wireless debugging gives developers hassle-free ADB connection*
<https://9to5google.com/2020/03/18/android-11-dp2-wireless-adb-debugging/>
"Simply put, Wireless debugging will let you leave your USB cable
behind and connect your phone to your computer via ADB completely
over Wi-Fi. Of course, considering how many potentially bad things
you can do to a phone once you have ADB access, it's not as simple
as just connect and go."

*Connect to a device over Wi-Fi (Android 11+)*
<https://developer.android.com/studio/command-line/adb>
"Android 11 and higher supports deploying and debugging your app
wirelessly from your workstation using Android Debug Bridge (adb).
This eliminates the need to deal with common USB connection issues,
such as driver installation.

To use wireless debugging, you must pair your device to your
workstation using a QR Code or a pairing code. Your workstation
and device must be connected to the same wireless network."

Even more useful perhaps is you can elevate a non-root phone's privileges.
*Wireless Debugging with Termux*
<https://youtu.be/KCODAyc_6rU>
1. On the Android phone, install Termux
2. In the Android Termux, type "pkg install android-tools"
3. On Android, turn on wireless debugging from the developer options menu
4. Then using only Android and no PC whatsoever, pair Android with itself!
% adb pair localhost:40737 <then add the 6-digit wi-fi pairing code>
5. On Android, use adb within Termux to connect wirelessly to itself.
% adb connect localhost:40737
6. At this point, you can drop into an adb shell inside of Android Termux.
% adb shell
# run-as com.termux
$
Apparently that gives you extra privileges even if you're not rooted.

What is interesing is the _power_ this provides, e.g., Frank Slootweg may
be interested that we can port forward over Wi-Fi (which means, perhaps,
just maybe we can finally connect on a non-rooted phone over SMB using
ports lower than 1024 on Android), and, for example, we can examine our
Android sqlite contacts database <https://www.sqlite.org/cli.html>.
$ adb -s emulator-5554 shell
$ sqlite3 /data/data/com.example.app/databases/rssitems.db
SQLite version 3.3.12
Enter ".help" for instructions

In summary, this ability to eliminate the USB cable completely is new as of
Android 11 and above. It allows us to more easily use adb over Wi-Fi, where
we can now perhaps elevate permissions temporarily (e.g., to delete
packages that are not delete able or to forward ports for SMB and to
examine the default protected contacts sqlite database on Android).
--
Usenet is where kind-hearted well educated people gather to exchange ideas.

[Andy Burnelli]

> a. The FOSS Windows android debugger (adb) is kind of flaky (IMHO).
> b. For whatever reason, adb sometimes loses the Wi-Fi connection over time.

Up until this moment, I couldn't figure out why adb was _still_ flaky.

I just figured out, belatedly so, yet another reason _why_ I keep losing
the adb Wi-Fi connection between Windows and Android for screen mirroring.
<https://i.postimg.cc/hPVtkTXK/adb02.jpg> Boot turns W/L debug off

Previously in this thread, Andy Burns had informed me that Android (11+)
has the ability to _initiate_ the connection between adb & Android over
Wi-Fi (but only if we turn on the Android "Wireless Debugging" option!).

Remember that in the past (prior to Android 11), the only way you could
_initiate_ adb pairing was over USB (and then, after pairing over USB, in
the past, you could disconnect the USB and stay connected over Wi-Fi).

Since Andy Burns kindly told me that, I've now been initiating and using
the connection over Wi-Fi while keeping the phone on the AC USB charger.

That works - but it too seemed to be a flaky adb screen mirror connection.

It seemed to be working fine while I was using it but after a while, when I
came back to the computer, it didn't work anymore, seemingly randomly so.
*I just realized that it's _not_ random!*

The reason turned out to be simple even as I had not expected it.
*Android 12 apparently turns that option _off_ each time you reboot!*

Who knew?
Not me.

Apparently Android 12 turns a _lot_ of things back on/off that you had
previously set to be off/on (such as screen rotation), which is a PITA.

The moral of the story is that Android 12, by default, does some pretty
stupid things after rebooting, which means you have to constantly remember
to manually turn those options _back_ to where you originally set them.

One of those idiotic things Android 12 does upon reboot is it turns off
Wi-Fi debugging - which necessitates turning it back on after every boot.
<https://i.postimg.cc/hPVtkTXK/adb02.jpg> Boot turns W/L debug off

Maybe it's just me, but isn't it stupid that Android unsets options
that you had previously set (like screen rotation & wireless debugging)?
--
Usenet allows people with shared interests to discuss topics of import.

[Andy Burnelli]

Andy Burnelli wrote:

> One of those idiotic things Android 12 does upon reboot is it turns off
> Wi-Fi debugging - which necessitates turning it back on after every boot.
> <https://i.postimg.cc/hPVtkTXK/adb02.jpg> Boot turns W/L debug off

Aurgh.

There's _another_ common situation where the wireless debugging option is
turned off without your action, which is if you turn off your Wi-Fi, even
for a moment.
<https://i.postimg.cc/9M0Tqzm6/adb01.jpg> Wireless debugging option
<https://i.postimg.cc/hPVtkTXK/adb02.jpg> Wi-Fi off turns W/L debug off

The bad news is Android 12 is incessant in turning _off_ the Wi-Fi
debugging Developer option since almost any disconnect from Wi-Fi turns the
setting off.

But luckily the good news it that once you know it's automatically turned
off by a bunch of things, you can manually turn it back on easily enough.

The reason you want to bother with "Wireless Debugging = On" is that it
allows you to mirror and control your Android phone over WiFi on your PC.

Note that you do not need Wireless Debugging to be set in order to mount
the entire Android native file system (even root) over Wi-Fi using WebDav.
NET USE Z: \\192.168.0.2\DavWWWRoot /USER:username password

Note that "DavWWWRoot" is simply whatever you've set it to be on the phone.
<https://i.postimg.cc/sxzR0Pg8/webdav01.jpg> WebDav has no sd permission
<https://i.postimg.cc/X7FS61HD/webdav02.jpg> X-plore has no permission
<https://i.postimg.cc/BvmRBrbt/webdav03.jpg> File Manager has permission
<https://i.postimg.cc/3xCsd4HX/webdav04.jpg> My Files has permission
<https://i.postimg.cc/Njm6ZXsc/webdav05.jpg> Permissions are the same
--
Posted out of the goodness of my heart to help others & to learn from them.