Why is mdns-discovery.exe always trying to access the network?

netweezurd · October 24, 2022, 3:06am

Hi guys,

On the network I'm on, everything is closed.

So I have the admin phoning me asking WTF.

So here, why is mdns-discovery.exe always trying to access the network?

I mean constantly... every 20 odd seconds!

Thank You.

Removed the image...

Grumpy_Mike · October 24, 2022, 7:47am

It is probable your admin checking there are no unauthorised things running in their network.
Or else you do not have a fire wall.

You really shouldn't post all that information about your network either or you might be getting the sack. Edit your post and remove the picture.erridicate those network numbers, edit the post agin and repost.

Anyway you posted in perhaps one of the two places on the forum you can't post a question concerning your project. You posted in the section for getting the IDE working, so I moved your post here.please be careful where you post in future.

ptillisch · October 24, 2022, 9:40am

Hi @netweezurd. mdns-discovery is a "pluggable discovery" tool used by Arduino IDE to identify the ports of Arduino boards that use the "ArduinoOTA" approach to communicate with the Arduino development tools over the network for things like OTA uploads. It detect the appearance and disappearance of such ports on the network so that the port listings such as you see in the Tools > Port menu of the Arduino IDE and the board selector dropdown on the Arduino IDE 2.x toolbar will reflect the ports currently available.

Some examples of uses of this capability:

https://arduino-esp8266.readthedocs.io/en/latest/ota_updates/readme.html#application-example

github.com

espressif/arduino-esp32/blob/2.0.5/libraries/ArduinoOTA/examples/BasicOTA/BasicOTA.ino

#include <WiFi.h>
#include <ESPmDNS.h>
#include <WiFiUdp.h>
#include <ArduinoOTA.h>

const char* ssid = "..........";
const char* password = "..........";

void setup() {
  Serial.begin(115200);
  Serial.println("Booting");
  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);
  while (WiFi.waitForConnectResult() != WL_CONNECTED) {
    Serial.println("Connection Failed! Rebooting...");
    delay(5000);
    ESP.restart();
  }

  // Port defaults to 3232

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netweezurd · October 25, 2022, 10:58pm

@Grumpy_Mike
The image was from a bogus test network I put up in the lab.
No useful information.

@ptillisch
Thank you for your reply.
Yes I figured what was mdns-discovery.

Can it be switched off ?

ptillisch · October 26, 2022, 12:31am

There isn't a formal way to do this. Even though we now have a nice "pluggable discovery" system where Arduino boards platforms can specify the discovery tools (including custom tools for any arbitrary protocol) they require for their boards, and the IDE only runs those tools when a platform requiring it is installed, this system is relatively recent. Previously, the discovery of serial ports and later network ports was built into the Arduino IDE 1.x codebase and always done, so the boards platform system did not have any need for a way to specify discovery tools. So serial-discovery and mdns-discovery are considered "builtin" tools that always run in order to provide backwards compatibility with the ~95% of existing boards platforms that don't specify discoveries.

There is a hack you can try though:

Select File > Quit from the Arduino IDE menus if it is currently running.
Rename or delete the file at this path:
```
C:\Users\<user name>\AppData\Local\Arduino15\packages\builtin\tools\mdns-discovery\1.0.6
```
(replacing <user name> with your Windows user name)
Please be very careful when deleting things from your computer. When in doubt, back up!
If looking for it with your file browser or command line, note that the C:\Users\<user name>\AppData\ folder is hidden by default. On Windows "File Explorer", you can make it visible by opening the "View" menu, then checking the box next to "☐ Hidden items".
Start the Arduino IDE.

The Arduino IDE currently has the behavior of silently ignoring a failure to start a discovery tool, so it will attempt to execute mdns-discovery.exe on startup, find the file is missing, and then simply move on with the startup.

It is possible this behavior might change at some time in the future, for example, there is a proposal here to make it attempt to reinstall the tool when this happens:

github.com/arduino/arduino-cli

Recover from interrupted discovery/monitor installation

opened 12:34PM - 18 Feb 22 UTC

closed 02:12PM - 15 May 23 UTC

per1234

type: enhancement conclusion: resolved topic: code

### Describe the request Reinstall pluggable discovery and monitor tools of t…he `builtin` package if the tool executable is not found. ### Describe the current behavior Arduino CLI automatically installs [pluggable discovery](https://arduino.github.io/arduino-cli/dev/pluggable-discovery-specification/) and [pluggable monitor](https://arduino.github.io/arduino-cli/dev/pluggable-monitor-specification/) tools of the `builtin` package when missing or updatable. These tools allow Arduino CLI to find the "ports" used for communication with Arduino boards. It can happen that the installation process is interrupted or interfered with. 🙁 If a problem during the installation results in the creation of the tool's release installation folder without the tool executable, Arduino CLI can no longer do discovery. It will not automatically recover from this condition and the user must manually delete the incomplete installation in order to restore Arduino CLI to functionality. #### To reproduce ```text $ arduino-cli version arduino-cli.exe Version: git-snapshot Commit: 2c2a5cc6 Date: 2023-04-22T13:21:59Z $ ls "C:\\Users\\per\\AppData\\Local\\Arduino15\\packages\\builtin\\tools\\serial-discovery" 1.4.0/ $ ls "C:\\Users\\per\\AppData\\Local\\Arduino15\\packages\\builtin\\tools\\serial-discovery\\1.4.0" LICENSE.txt serial-discovery.exe* $ rm "C:\\Users\\per\\AppData\\Local\\Arduino15\\packages\\builtin\\tools\\serial-discovery\1.4.0\\serial-discovery.exe" $ arduino-cli board list Error starting discovery: discovery builtin:serial-discovery process not started: exec: "C:\\Users\\per\\AppData\\Local\\Arduino15\\packages\\builtin\\tools\\serial-discovery\\1.4.0\\serial-discovery": file does not exist No boards found. ``` ### Arduino CLI version 2c2a5cc6 ### Operating system Windows, Linux ### Operating system version Windows 11, Ubuntu 22.04 ## Additional context Originally reported at https://forum.arduino.cc/t/ide-2-0-lost-all-com-ports/960650 --- This situation is more problematic for Arduino IDE users, since the error message about the missing tool is not visible to them and they only notice the symptom of the IDE not seeing their ports. --- It might seem unlikely for this interrupted installation to occur under real world conditions, but the equivalent issue with Boards Manager producing incomplete tools installations has been reported by users periodically ever since the introduction of Boards Manager, at sufficient volume for Arduino Support to consider it worth a Help Center article: https://support.arduino.cc/hc/en-us/articles/360018444739-Error-file-does-not-exist-no-such-file-or-directory-system-cannot-find-the-file-specified

But there are no immediate plans for any such change that I am aware of. An alternative workaround can be devised if the time comes when the current hack stops working.

Something you should be aware of is that the IDE will automatically install new versions of mdns-discovery when they are released by Arduino. You will need to repeat the process at that time, following the same procedure described above, with the only difference being the version component of the path (currently 1.0.6).

system · April 24, 2023, 12:32am

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Why is mdns-discovery.exe always trying to access the network?

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