Linux container Proxy Problem

Docker Desktop for Windows
1

Hi all,

I am new to Docker and just startet my first steps with Docker for Windows on Windows 10. I installed the newest version of Docker and updated Windows10.

I am running my system in a corporate environment behind a common security layer. For outbound connections we have to use an ntlm proxy. To do so I installed cntlm on my local machine and configured the ntlm client and Docker (defining the proxy properties in the UI) appropriately. If I configure Docker to use “Windows containers” everything works like a charm. If I switch to “Linux Containers” the call seems to disapear.

A simple docker run hello-world quits with following error message: “Error response from daemon: Get https://registry-1.docker.io/v2/: proxyconnect tcp: dial tcp 127.0.0.1:3128: getsockopt: connection refused.”

Obviously the Linux Container mode seems to do things differently from the Windows mode. The call in Linux mode doesnt even reach the local ntlm client. Wireshark doesnt show any network traffic. What is the difference between the two modes.

Any advice or help is highly appreciated.

Best regards
Nikolas

2

Problem solved!
Run cntlm in gateway mode AND use the correct IP (i.e. the “external IP” of your Windows network adapter).
Obviously in Linux mode the additional virtualization layer needs the docker proxy IP to be defined differently.

3

I am having the same issue. Can you please explain in detail steps what does “Run cntlm in gateway mode” and Where do I use the correct “external IP” ?