id = 812
title = "Multicast packets (mDNS) are not sent out of VM"
state = "closed"
created_at = "2022-01-11T18:23:24.919Z"
closed_at = "2022-01-12T19:13:10.142Z"
labels = ["Networking"]
url = "https://gitlab.com/qemu-project/qemu/-/issues/812"
host-os = "macOS BigSur 11.6"
host-arch = "x86_64"
qemu-version = "QEMU emulator version 6.0.0"
guest-os = "Alpine Linux 3.14"
guest-arch = "x86_64"
description = """The app is sending multicast packets (mDNS), but they are not sent out of VM.
Here is the configuration of the network: `-netdev user,id=net0,hostfwd=tcp::2222-:22,hostfwd=tcp::50051-:50051,hostfwd=tcp::50050-:50050`"""
reproduce = """1. Install arduino-cli from https://github.com/arduino/arduino-cli/releases (eg. 0.20.2)
2. `arduino-cli config init`
3. `vi ~/.arduino15/arduino-cli.yaml`
4. edit it to have it as follows:
```
board_manager:
  additional_urls: ["http://arduino.esp8266.com/stable/package_esp8266com_index.json"]
daemon:
  port: "50051"
directories:
  data: /root/app/data
  downloads: /root/app/downloads
  user: /root/app/user
library:
  enable_unsafe_install: false
logging:
  file: ""
  format: text
  level: info
metrics:
  addr: :9090
  enabled: false
output:
  no_color: false
sketch:
  always_export_binaries: false
updater:
  enable_notification: true
```

5. `arduino-cli core update-index`
6. `arduino-cli core install esp8266:esp8266`
7. `arduino-cli board list -v`

This will give an output similar to:
```
INFO[0000] Using config file: /root/.arduino15/arduino-cli.yaml 
INFO[0000] arduino-cli.x86_64 version git-snapshot      
INFO[0000] Checking if CLI is Bundled into the IDE      
INFO[0000] Adding libraries dir                          dir=/root/app/user/libraries location=user
INFO[0000] Checking signature                            index=/root/app/data/package_index.json signatureFile=/root/app/data/package_index.json.sig =
INFO[0000] Checking signature                            error="opening signature file: open /root/app/data/package_esp8266com_index.json.sig: no such file or d=
INFO[0000] Loading hardware from: /root/app/data/packages 
INFO[0000] Loading package builtin from: /root/app/data/packages/builtin 
INFO[0000] Checking existence of 'tools' path: /root/app/data/packages/builtin/tools 
INFO[0000] Loading tools from dir: /root/app/data/packages/builtin/tools 
INFO[0000] Loaded tool                                   tool="builtin:ctags@5.8-arduino11"
INFO[0000] Loaded tool                                   tool="builtin:mdns-discovery@1.0.2"
INFO[0000] Loaded tool                                   tool="builtin:serial-discovery@1.3.1"
INFO[0000] Loaded tool                                   tool="builtin:serial-monitor@0.9.1"
INFO[0000] Loading package esp8266 from: /root/app/data/packages/esp8266/hardware 
INFO[0000] Checking signature                            error="opening signature file: open /root/app/data/packages/esp8266/hardware/esp8266/3.0.2/installed.js=
INFO[0000] Adding monitor tool                           protocol=serial tool="builtin:serial-monitor"
INFO[0000] Loaded platform                               platform="esp8266:esp8266@3.0.2"
INFO[0000] Checking existence of 'tools' path: /root/app/data/packages/esp8266/tools 
INFO[0000] Loading tools from dir: /root/app/data/packages/esp8266/tools 
INFO[0000] Loaded tool                                   tool="esp8266:mklittlefs@3.0.4-gcc10.3-1757bed"
INFO[0000] Loaded tool                                   tool="esp8266:mkspiffs@3.0.4-gcc10.3-1757bed"
INFO[0000] Loaded tool                                   tool="esp8266:python3@3.7.2-post1"
INFO[0000] Loaded tool                                   tool="esp8266:xtensa-lx106-elf-gcc@3.0.4-gcc10.3-1757bed"
INFO[0000] Adding libraries dir                          dir=/root/app/data/packages/esp8266/hardware/esp8266/3.0.2/libraries location=platform
INFO[0007] Executing `arduino-cli board list`           
INFO[0007] starting discovery builtin:serial-discovery process 
INFO[0007] started discovery builtin:serial-discovery process 
INFO[0007] sending command HELLO 1 "arduino-cli git-snapshot" to discovery builtin:serial-discovery 
INFO[0007] starting discovery builtin:mdns-discovery process 
INFO[0007] started discovery builtin:mdns-discovery process 
INFO[0007] sending command HELLO 1 "arduino-cli git-snapshot" to discovery builtin:mdns-discovery 
INFO[0007] from discovery builtin:serial-discovery received message type: hello, message: OK, protocol version: 1 
INFO[0007] from discovery builtin:mdns-discovery received message type: hello, message: OK, protocol version: 1 
INFO[0007] sending command START to discovery builtin:serial-discovery 
INFO[0007] sending command START to discovery builtin:mdns-discovery 
INFO[0007] from discovery builtin:mdns-discovery received message type: start, message: OK 
INFO[0007] from discovery builtin:serial-discovery received message type: start, message: OK 
INFO[0008] sending command LIST to discovery builtin:serial-discovery 
INFO[0008] sending command LIST to discovery builtin:mdns-discovery 
INFO[0008] from discovery builtin:mdns-discovery received message type: list 
INFO[0008] from discovery builtin:serial-discovery received message type: list, ports: [/dev/ttyS0] 
INFO[0008] sending command STOP to discovery builtin:serial-discovery 
INFO[0008] sending command STOP to discovery builtin:mdns-discovery 
INFO[0008] from discovery builtin:mdns-discovery received message type: stop, message: OK 
INFO[0008] from discovery builtin:serial-discovery received message type: stop, message: OK 
Port       Protocol Type    Board Name FQBN Core
/dev/ttyS0 serial   Unknown                
```

Note `builtin:mdns-discovery` discovery started. It is expected to send the packets as follows (the screenshot from the host with Wireshark):

![Снимок_экрана_2022-01-11_в_22.49.58](/uploads/4c2783c84aaa323bc9dfbca127494768/Снимок_экрана_2022-01-11_в_22.49.58.png)

The screenshot is taken if running the same app (but for macOS) from the host and **i can't see the packets sent if executed from the QEMU guest os**.
I believe i either configured it the wrong way (`-netdev user,id=net0,...`) or it's a QEMU bug."""
additional = """I've tested on macOS host with qemu 6.0.0 and on Linux (Android) host with qemu 6.1.0 and both were not working.

the network interface seems to be configured for multicasting:
```
# ifconfig
eth0      Link encap:Ethernet  HWaddr 52:54:00:12:34:57  
          inet addr:10.0.2.15  Bcast:0.0.0.0  Mask:255.255.255.0
          inet6 addr: fec0::5054:ff:fe12:3457/64 Scope:Site
          inet6 addr: fe80::5054:ff:fe12:3457/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:91955 errors:0 dropped:0 overruns:0 frame:0
          TX packets:25203 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:119904373 (114.3 MiB)  TX bytes:1868274 (1.7 MiB)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
```

It might be easier to skip using arduino-cli and just use any mdns discovery app."""