Docker login error with Get Started tutorial - authentication

Question

I'm trying to follow beginner tutorial on Docker's website and I suffer with an error on login.
OS is Ubuntu 14.04, I'm not using VirtualBox and I'm not behind any proxy and want to push to the "regular" docker repository (not private one).
All threads I've found mention proxies and private repositories but that isn't my case, I'm just trying to do simple beginner tutorial.
Here is my attempt:
$ sudo docker login
[sudo] password for myuname:
Login with your Docker ID to push and pull images from Docker Hub. If you don't have a Docker ID, head over to https://hub.docker.com to create one.
Username: myDHuname
Password:
Error response from daemon: Get https://registry-1.docker.io/v2/: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
My docker info:
Containers: 5
Running: 0
Paused: 0
Stopped: 5
Images: 5
Server Version: 1.11.0
Storage Driver: aufs
Root Dir: /var/lib/docker/aufs
Backing Filesystem: extfs
Dirs: 28
Dirperm1 Supported: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
Volume: local
Network: bridge null host
Kernel Version: 3.19.0-58-generic
Operating System: Ubuntu 14.04.4 LTS
OSType: linux
Architecture: x86_64
CPUs: 4
Total Memory: 7.686 GiB
Name: myuname-ThinkPad-T420
ID: 6RW3:X3FC:T62N:CWKI:JQW5:YIPY:RAHO:ZHF4:DFZ6:ZL7X:JPOD:V7EC
Docker Root Dir: /var/lib/docker
Debug mode (client): false
Debug mode (server): false
Registry: https://index.docker.io/v1/
WARNING: No swap limit support
Epilogue
Now docker login is passing. I have not touched anything since yesterday when it was broken...
I can't reproduce the behavior anymore.

Answer 1

I encounter this issue when my first use docker. I've shadowsocks proxy on, and configed as pac mode. When I try to run docker run hello-world, I get this timeout error. When I set the proxy mode to global, the error is aslo there.
But when I disable the proxy, docker runs well. It pull remote image successfully.
docker for windows
Note: Some users reported problems connecting to Docker Hub on Docker
for Windows stable version. This would manifest as an error when
trying to run docker commands that pull images from Docker Hub that
are not already downloaded, such as a first time run of docker run
hello-world. If you encounter this, reset the DNS server to use the
Google DNS fixed address: 8.8.8.8. For more information, see
Networking issues in Troubleshooting.

Answer 2

The error Client.Timeout exceeded while awaiting headers indicates:
GET request to the registry https://registry-1.docker.io/v2/ timedout
The library responsible (most likely libcurl) timed out before a response was heard
The connection never formed (proxy/firewall gobbled it up)
If you see the below result you can rule out timed out and network connectivity
$ curl https://registry-1.docker.io/v2/
{"errors":[{"code":"UNAUTHORIZED","message":"authentication required","detail":null}]}
If you get the above response next would be to check if your user environment has some proxy configuration.
env | grep "proxy"
Note: The docker runs as root. Maybe you have http_proxy in your env. Most likely I am wrong. Anywho see what happens with the curl GET request

Answer 3

change the proxy settings in the firefox. May be you are in access restricted mode. Just add the server address in the firefox settings -> preferences -> advanced -> network -> configuration (settings). Add the server ip in the no proxy for the issue can be resolved