UDP publishing using docker

[hcoeuret]

Which version are you using?

v0.0.0

Which operating system are you using?

OS

• Linux
• Windows
• macOS

Architecture

• amd64
• arm64
• arm7
• arm6

Describe the issue

Description

For an application, I want to publish an UDP stream to the server. Once published I want to open it with vlc or ffplay. Using TCP, it works, but with UDP, it won't.

I start the server with
docker run --rm -it -e RTSP_PROTOCOLS=udp -p 8554:8554 aler9/rtsp-simple-server

I publish a stream with ffmpeg
./ffmpeg -i testVideo.mp4 -rtsp_transport udp -f rtsp rtsp://localhost:8554/mystream

I get the following error
2021/02/23 10:23:43 [I] [1/0/0] [client 172.17.0.1:59268] connected (plain) 2021/02/23 10:23:43 [I] [1/1/0] [client 172.17.0.1:59268] is publishing to path 'mystream', 1 track with udp 2021/02/23 10:23:53 [I] [1/1/0] [client 172.17.0.1:59268] ERR: no UDP packets received recently (maybe there's a firewall/NAT in between) 2021/02/23 10:23:53 [I] [0/0/0] [client 172.17.0.1:59268] disconnected

From Wireshark I can see "destination unreachable (port unreachable)" packets

Starting the server with this command line get ffmpeg to block
docker run --rm -it --network=host aler9/rtsp-simple-server

ffmpeg :
./ffmpeg -re -stream_loop -1 -i testVideo.mp4 -f rtsp rtsp://localhost:8554/mystream

errors:
Could not write header for output file #0 (incorrect codec parameters ?): Immediate exit requested Error initializing output stream 0:0 --

Everything works fine using the windows precompiled binaries, so I assume it's a network problem.

Did you attach a network dump?

no

[mateusz28]

Hi,
I've encountered similar issue on Linux Docker (I can not use host network mode in my scenario) but I've manged to overcome it by disabling userland proxy in docker daemon. It can be done in Linux by adding to docker daemon config file and restarting daemon:
/etc/docker/daemon.json

{
    "userland-proxy": false
}

With this docker daemon option host networking is not required, exposing udp ports is sufficient.
Although docker on Windows requires this option to allow localhost connections to be forwarded so this probably can not be used in your scenario. I think this may explain also why UDP connection to docker on Windows is not working as expected.

[aler9]

Unfortunately RTSP with UDP requires a direct connection between client and server - i'm working to add support for another protocol (SRT) that doesn't require it.