My docker container has no internet

Question

I had it working allright but now it stopped  I tried the following commands with no avail   docker run -dns 8 8 8 8 base ping google com  docker run base ping google com  sysctl -w net ipv4 ip forward 1 - both on the host and on the container  All I get is unknown host google com   Docker version 0 7 0  Any ideas   P S  ufw disabled as well

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For me it was the host s firewall  I had to allow DNS on the host s firewall  And also had to restart docker after changing the host firewall setting

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I do not know what I am doing but that worked for me    OTHER BRIDGE br-xxxxx   this is the other random docker bridge   ip addr  to find      service docker stop  ip link set dev  OTHER BRIDGE down ip link set dev docker0 down ip link delete  OTHER BRIDGE type bridge ip link delete docker0 type bridge service docker start  amp  amp  service docker stop  iptables -t nat -A POSTROUTING   -o docker0 -s 172 17 0 0 16 -j MASQUERADE iptables -t nat -A POSTROUTING   -o docker0 -s 172 18 0 0 16 -j MASQUERADE  service docker start

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I was stumped when this happened randomly for me for one of my containers  while the other containers were fine  The container was attached to at least one non-internal network  so there was nothing wrong with the Compose definition  Restarting the VM   docker daemon did not help  It was also not a DNS issue because the container could not even ping an external IP   What solved it for me was to recreate the docker network s   In my case  docker-compose down  amp  amp  docker-compose up worked   Compose  This forces the recreation of all networks of all the containers   docker-compose down  amp  amp  docker-compose up  Swarm mode  I suppose you just remove and recreate the service  which recreates the service s network s    docker service rm some-service  docker service create      If the container s network s  are external  Simply remove and recreate the external networks of that service   docker network rm some-external-network   docker network create some-external-network

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On centos 8  My problem was that I did not install  amp  start iptables before starting docker service  Make sure iptables service is up and running before you start docker service

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for me  my problem was because of iptables-services was not installed  this worked for me  CentOS    sudo yum install iptables-services sudo service docker restart

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I was using DOCKER OPTS  --dns 8 8 8 8  and later discovered and that my container didn t have direct access to internet but could access my corporate intranet  I changed DOCKER OPTS to the following   DOCKER OPTS  --dns  lt internal corporate dns address    replacing internal corporate dns address with the IP address or FQDN of our DNS and restarted docker using  sudo service docker restart   and then spawned my container and checked that it had access to internet

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For me it was an iptables forwarding rule  For some reason the following rule  when coupled with docker s iptables rules  caused all outbound traffic from containers to hit localhost 8080   iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT --to-ports 8080 iptables -t nat -I OUTPUT -p tcp -d 127 0 0 1 --dport 80 -j REDIRECT --to-ports 8080

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for me  using centos 7 4  it was not issue of  etc resolve conf  iptables  iptables nat rules nor docker itself  The issue is the host missing the package bridge-utils which docker require to build the bridge using command brctl  yum install -y bridge-utils and restart docker  solve the problem

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No internet access can also be caused by missing proxy settings  In that case  --network host may not work either  The proxy can be configured by setting the environment variables http proxy and https proxy   docker run -e  http proxy YOUR-PROXY               -e  https proxy YOUR-PROXY              -e  no proxy localhost 127 0 0 1         Do not forget to set no proxy as well  or all requests  including those to localhost  will go through the proxy   More information  Proxy Settings in the Archlinux Wiki

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Just adding this here in case someone runs into this issue within a virtualbox container running docker  I reconfigured the virtualbox network to bridged instead of nat  and the problem went away

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I ve had a similar problem for the last few days  For me the cause was a combination of systemd  docker and my hosting provider  I m running up-to-date CentOS  7 7 1908    My hosting provider automatically generates a config file for systemd-networkd  Starting with systemd 219 which is the current version for CentOS 7  systemd-networkd took control of network-related sysctl parameters  Docker seems to be incompatible with this version and will reset the IP-Forwarding flags everytime a container is launched   My solution was to add IPForward true in the  Network -section of my provider-generated config file  This file might be in several places  most likely in  etc systemd network   The process is also described in the official docker docs  https   docs docker com v17 09 engine installation linux linux-postinstall  ip-forwarding-problems

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The intended way to restart docker is not to do it manually but use the service or init command   service docker restart

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Updating this question with an answer for OSX  using Docker Machine   If you are running Docker on OSX using Docker Machine  then the following worked for me   docker-machine restart   lt    wait for it to restart  which takes up to a minute    gt   docker-machine env eval   docker-machine env    Then  at least in my experience   if you ping google com from a container all will be well

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On windows  8 1  I killed the virtualbox interface  via taskmgr  and it solved the issue

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If you re on OSX  you might need to restart your machine after installing Docker   This has been an issue at times

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For Ubuntu 19 04 using openconnect 8 3 for VPN  I had to symlink  etc resolve conf to the one in systemd  opposite of answerby wisbucky     sudo ln -sf  etc resolv conf  run systemd resolve resolv conf  Steps to debug   Connect to Company VPN Look for correct VPN settings in either  etc resolv conf or  run systemd resolve resolv conf  Whichever has the correct DNS settings  we ll symlink that to the other file   Hint  Place one with correct settings on the left of assignment     Docker version  Docker version 19 03 0-rc2  build f97efcc

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Originally my docker container was able to reach the external internet  This is a docker service container running on an Amazon EC2    Since my app is an API  I followed up the creation of my container  it succeeded in pulling all the packages it needed  with updating my IP Tables to route all traffic from port 80 to the port that my API  running on docker  was listening on   Then  later when I tried rebuilding the container it failed  After much struggle  I discovered that my previous step  setting the IPTable port forwarding rule  messed up the docker s external networking capability   Solution  Stop your IPTable service   sudo service iptables stop  Restart The Docker Daemon   sudo service docker restart  Then  try rebuilding your container  Hope this helps     Follow Up  I completely overlooked that I did not need to mess with the IP Tables to forward incoming traffic to 80 to the port that the API running on docker was running on  Instead  I just aliased port 80 to the port the API in docker was running on   docker run -d -p 80  lt api port gt   lt image gt   lt tag gt   lt command to start api gt

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First thing to check is run cat  etc resolv conf in the docker container  If it has an invalid DNS server  such as nameserver 127 0 x x  then the container will not be able to resolve the domain names into ip addresses  so ping google com will fail   Second thing to check is run cat  etc resolv conf on the host machine  Docker basically copies the host s  etc resolv conf to the container everytime a container is started  So if the host s  etc resolv conf is wrong  then so will the docker container   If you have found that the host s  etc resolv conf is wrong  then you have 2 options    Hardcode the DNS server in daemon json  This is easy  but not ideal if you expect the DNS server to change  Fix the hosts s  etc resolv conf  This is a little trickier  but it is generated dynamically  and you are not hardcoding the DNS server      1  Hardcode DNS server in docker daemon json   Edit  etc docker daemon json         dns     10 1 2 3    8 8 8 8      Restart the docker daemon for those changes to take effect  sudo systemctl restart docker Now when you run start a container  docker will populate  etc resolv conf with the values from daemon json      2  Fix the hosts s  etc resolv conf  A  Ubuntu 16 04 and earlier   For Ubuntu 16 04 and earlier   etc resolv conf was dynamically generated by NetworkManager   Comment out the line dns dnsmasq  with a    in    etc NetworkManager NetworkManager conf Restart the NetworkManager to regenerate  etc resolv conf   sudo systemctl restart network-manager Verify on the host  cat  etc resolv conf   B  Ubuntu 18 04 and later   Ubuntu 18 04 changed to use systemd-resolved to generate  etc resolv conf  Now by default it uses a local DNS cache 127 0 0 53  That will not work inside a container  so Docker will default to Google s 8 8 8 8 DNS server  which may break for people behind a firewall   etc resolv conf is actually a symlink  ls -l  etc resolv conf  which points to  run systemd resolve stub-resolv conf  127 0 0 53  by default in Ubuntu 18 04  Just change the symlink to point to  run systemd resolve resolv conf  which lists the real DNS servers  sudo ln -sf  run systemd resolve resolv conf  etc resolv conf Verify on the host  cat  etc resolv conf   Now you should have a valid  etc resolv conf on the host for docker to copy into the containers

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You may have started your docker with dns options --dns 172 x x x  I had the same error and removed the options from  etc default docker  The lines      Use DOCKER OPTS to modify the daemon startup options  DOCKER OPTS  --dns 172 x x x

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Sharing a simple and working solution for posterity  When we run a docker container without explicitly mentioning the --network flag  it connects to its default bridge network which prohibits connecting to the outside world  To resolve this issue  we have to create our own bridge network user-defined bridge  and have to explicitly mention it with the docker run command  docker network create --driver bridge mynetwork docker run -it --network mynetwork image version

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I also encountered such an issue while trying to set up a project using Docker-Compose on Ubuntu    The Docker had no access to internet at all  when I tried to ping any IP address or nslookup some URL - it failed all the time   I tried all the possible solutions with DNS resolution described above to no avail    I spent the whole day trying to find out what the heck is going on  and finally found out that the cause of all the trouble was the antivirus  in particular it s firewall which for some reason blocked Docker from getting the IP address and port    When I disabled it - everything worked fine   So  if you have an antivirus installed and nothing helps fix the issue - the problem could be the firewall of the antivirus

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Fixed by following this advice         can you try to reset everything   pkill docker iptables -t nat -F ifconfig docker0 down brctl delbr docker0 docker -d   It will force docker to recreate the bridge and reinit all the network rules  https   github com dotcloud docker issues 866 issuecomment-19218300 Seems the interface was  hung  somehow  Update for more recent versions of docker  The above answer might still get the job done for you but it has been quite a long time since this answer was posted and docker is more polished now so make sure you try these first before going into mangling with iptables and all  sudo service docker restart or  if you are in a linux distro that does not use upstart  sudo systemctl restart docker

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I had the problem on Ubuntu 18 04  However the problem was with the DNS  I was in a corporate network that has its own DNS server and block other DNS servers  This is to block some websites  porn  torrents      so on     To resolve your problem    find your DNS on host machine  use --dns your dns as suggested by  jobin   docker run --dns your dns -it --name cowsay --hostname cowsay debian bash

[docker] My docker container has no internet

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