No Internet Access In Docker Container When Connected to Cisco AnyConnect VPN

Question

I am connected to a corporate VPN and need to be able to run docker containers while the VPN is connected due to the fact that the container needs to be able to access corporate endpoints. However, when I am connected with AnyConnect VPN, docker has no internet access at all. Neither to our corporate endpoints or the internet.

I am running CentOS7 as my host operating system.

A simple way to reproduce this issue is to install a minimal linux distro, install AnyConnect VPN, connect to vpn and try to run the following docker container:

docker run -i -t ubuntu:14.04 /bin/bash

Once inside the container I try to ping google dns

[###]$ ping 8.8.8.8

There will be no response. If I disconnect from AnyConnect VPN and retry the above, I get a ping response.

How can I fix this issue?

Answer 1

After you make a change to the network interfaces, you often need to restart the docker engine to rebuild all of the routes and iptables entries. With Linux and systemd, use:

systemctl restart docker