Docker strange network behaviour

General
1

Hi all. I have the following

  • OS: Ubuntu 22.04.1 LTS, kernel 5.15
  • Docker version: 20.10.21

I create a network with
docker network create net_test

then run

*docker run -d --name srvr_tester --network=*net_test python:3.8 python -m http.server 443

then from outside I tried to run
curl -X ‘GET’ --insecure http://192.168.192.13:443/etc/resolv.conf

and it goes in timeout.

I ve been checking FW and IPTABLES but still nothing.
any clue?

Cheers

2

Can you elaborate, why this should work?

Assumed 192.168.192.13 is the docker host’s ip, then the behavior is correct.

If you want a container to be reachable on a host network port, you need to publish it:

3

My apologies.
Here is the command that I run.

docker run -d -p 443:8000 --name srvr_tester --network=net_test python:3.8 python -m http.server 8000

/Alf

4

Since you shared a different command does that mean you solved the issue by publishing the port?

5

Hi @rimelek.
it was my mistake posting the wrng command so still not working.
{
“bip”: “[10.9.8.1/24]”,
“fixed-cidr”: “[10.9.8.0/25]”,
“fixed-cidr-v6”: “2001:db8::/64”,
“default-address-pools”:[{“base”:“[10.0.0.0/24]”, “size”:28}],
“mtu”: 1500,
“dns”: [“10.26.16.16”,“10.26.16.18”],
“dns-search”: [“mycompany.com”]
}

It looks like the request arrive at the eth0 device but it’s not passed on neither to the docker bridge or veth interface.
Some setting on the kernel that I am missing
Cheers

6

If

  • you are using the right port number (the port on the left side in the docker command)
  • and there is no firewall blocking the request
  • and you have the same port in the docker command on the left side as the application is listening on inside

your request should work.

  • How and what did you check exactly?
  • Do you have any firewall in front of the destinations server?
  • Can you successfully run the curl comand on the server using the same IP that you want to access remotely?
  • Have you tried to disable ufw on the server just for testing (if it is not a public, production server)
    sudo ufw disable