How to communicate between Docker container and Linux host over SCTP - docker

Question

I tried to listen to SCTP on the docker container and connect to there from the Linux host machine. But it seems the connection timed out.
Is there any way to communicate between host and container over SCTP?
FYI: It looks container-to-container SCTP communication works fine.
Detailed information is the following:
Dockerfile for test-container
FROM ubuntu:focal
RUN apt update -y && apt install -y ncat
docker run
$ sudo docker run --rm --name sctp-server -p 9999:9999/sctp test-container:latest ncat --sctp -lv 9999
SCTP request (timeout)
$ ncat --sctp 127.0.0.1 9999
Ncat: TIMEOUT.
docker version
Client: Docker Engine - Community
Version: 19.03.13
API version: 1.40
Go version: go1.13.15
Git commit: 4484c46d9d
Built: Wed Sep 16 17:02:52 2020
OS/Arch: linux/amd64
Experimental: false
Server: Docker Engine - Community
Engine:
Version: 19.03.13
API version: 1.40 (minimum version 1.12)
Go version: go1.13.15
Git commit: 4484c46d9d
Built: Wed Sep 16 17:01:20 2020
OS/Arch: linux/amd64
Experimental: false
containerd:
Version: 1.3.7
GitCommit: 8fba4e9a7d01810a393d5d25a3621dc101981175
runc:
Version: 1.0.0-rc10
GitCommit: dc9208a3303feef5b3839f4323d9beb36df0a9dd
docker-init:
Version: 0.18.0
GitCommit: fec3683
FYI: Container-to-Container SCTP communication (works fine)
$ sudo docker network create -d bridge sctp
$ sudo docker run --rm --name sctp-server --net=sctp sctp-test:latest ncat --sctp -lv 9999
$ sudo docker run --rm --name sctp-client --net=sctp sctp-test:latest ncat --sctp 172.18.0.2 9999

Answer 1

Finally, I found the cause of this problem.
The reason for the timeout is it used the same SCTP port between host and container.
When I launched a container with
different ports like sudo docker run --rm --name sctp-server -p 19999:9999/sctp test-container:latest ncat --sctp -lv 9999 and run ncat --sctp 127.0.0.1 19999 on the host machine, it worked fine.
I'm not confident but I suspect the behavior of iptables.