Everytime I try to start any container in bridged network mode, the virtual network adapter is not added to the docker0 bridge. As a result, these containers don't have access to the network. I see the docker0 bridge and vethXXXXXX#ifXXX virtual interface from ip addr. However, brctl show shows the docker0 bridge with no interface attached. I can manually add the interface using brctl addif vethXXXXXX docker0 and everything works fine.
Some containers exit so quickly due to the connection problem that I don't have a chance to add them before they get a new virtual interface when restarting.
I already deleted all the docker network adapter and let them reinitialize by restarting docker, without success.
Does anybody know how I can fix this, so that network interfaces of container get automatically added to the docker0 bridge on startup?
Thanks
You can use networkctl to check veth status.
networkctl status -a
It might match incorrect network setting. You can use another higher priority systemd-networkd setting to correct it.
ex:
Create a new file /etc/systemd/network/20-docker-veth.network
with content
[Match]
Name=veth*
Driver=veth
[Link]
Unmanaged=true
and restart the systemd-networkd service.
sudo systemctl restart systemd-networkd.service
Then, start a new container with bridge network would auto link to veth.
ref: https://forums.docker.com/t/archlinux-container-veth-interfaces-being-assigned-to-wrong-bridge/107197/2
Related
I am new to the docker world. I am currently setting up an custom application which relies on docker. The setup requires docker container to connect my outside network. All is working well but the container is unable to connect to outside network. After initial investiagtion and tcpdump I came to know that docker container can connect to the outside world. The packet is forwaded to the docker0 interface and docker0 has forwarded the packet to the eth0(physical interface), the eth0 then forwards the packet to the outside world and receives reponse. Now this is where the problem is, the eth0 after receiving reposne doesnot forward the packet to the docker0 interface and finally to the end host.
The below is the iptable run which are all set to default.
Also tcpdump output
Inteface present on th host
HOST OS is SUSE Ent linux 15.3
Docker version 20.10.17-ce, build a89b84221c85
I will be very much grateful for any reponse.
Thank You
I am running some frr (free range routing) and ceos (Arista) containers on an "Ubuntu Docker Host" which is running on Virtual Box on Windows 10.
I created a macvlan network (net3) and tied it to enp interface of Ubuntu and connected my containers to it. However I cannot access my containers using their interfaces connected to the macvlan network.
I read about some limitations about network spaces between host and containers and saw macvlan network type as the solution to overcome those limitations. However it did not work.
Since my container is a router with multiple interfaces, I was expecting I can connect my new net3 network to my container. It would appear as a new new interface (it did) and when I assign an IP address from my home network to this interface, my router would be able to communicate to the outside directly using this interface`s IP address and bypass any sort of firewalling, NAT etc.
I know that we can use bridge networks connected to default docker0 network and which will then NAT outgoing connections from container and accept incoming connections if we publish a port etc. However what I want is to have a container with 2 interfaces, where one interface is in docker0 bridge and the other one is connected to the home network with an IP address from home network, which will expose it to the outside completely like a physical machine or my docket host Ubuntu VM.
I think i found a way to make this work.
added a new bridged network
added an iptables rule permitting traffic destined to this new bridged network at "Forward Chain".
What I do not understand now is that although the routing is disabled on the host, this "forward" rule has an impact on the traffic and it is actually working. I also did not need to add a rule traffic for return traffic. Default rules added by Docker during creation of the container seem to take care of this direction.
I would like to remove the interface docker0. It would be better to avoid creating the interface docker0 when starting the service and using directly the eth0.
To delete the interface, use:
ip link delete docker0
You may require sudo privilege.
By default, the Docker server creates and configures the host system’s docker0 interface as an Ethernet bridge inside the Linux kernel that can pass packets back and forth between other physical or virtual network interfaces so that they behave as a single Ethernet network.
Look at Understand Docker container networks and Customize the docker0 bridge
When you install Docker, it creates three networks automatically. You can list these networks using the docker network ls command:
$ docker network ls
Historically, these three networks (bridge, none, host) are part of Docker’s implementation. When you run a container you can use the --network flag to specify which network you want to run a container on. These three networks are still available to you.
The bridge network represents the docker0 network present in all Docker installations. Unless you specify otherwise with the docker run --network= option, the Docker daemon connects containers to this network by default. You can see this bridge as part of a host’s network stack by using the ifconfig command on the host.
I support #gile's solution.
Be careful when removing interfaces. I do not recommend you to remove bridge docker0 (the default docker0 is as a bridge - in my case).
The documentation says:
Bridge networks are usually used when you are in standalone containers
that need to communicate.
https://docs.docker.com/network/#network-drivers
If you want to remove this interface, you can use the following tools in addition to the above solutions (for removing / adding interfaces I suggest you use the tools provided with the docker):
nmcli connection delete docker0
docker network rm docker0
brctl delbr docker0
If you don't want to create docker0 interface at all when docker starts then edit daemon.json(which is configuration file for docker) file to add line "bridge": "none" line to that json.
I have trouble with connecting to VPN after installing docker. The solution would be the following:
You can see the ip route table by executing ip route command in linux. Then delete any domains start with 172.16.x.x.
For example:
> ip route
default via 192.168.1.1 dev wlp2s0 proto dhcp metric 20600
169.254.0.0/16 dev wlp2s0 scope link metric 1000
172.16.14.0/24 dev vmnet8 proto kernel scope link src 172.16.14.1
172.16.57.0/24 dev vmnet1 proto kernel scope link src 172.16.57.1
192.168.1.0/24 dev wlp2s0 proto kernel scope link src 192.168.1.4 metric 600
Then delete them like the following:
sudo ip route del 172.16.14.0/24 dev vmnet8 proto kernel scope link src 172.16.14.1
sudo ip route del 172.16.57.0/24 dev vmnet1 proto kernel scope link src 172.16.57.1
I run docker with my private eth0m interface as explained here
I want to run docker without docker0 and 172.... interface
how to disable docker0?
Why would you remove docker0 ?
When Docker starts, it creates a virtual interface named docker0 on the host machine.
[...]
But docker0 is no ordinary interface. It is a virtual Ethernet bridge that automatically forwards packets between any other network interfaces that are attached to it. This lets containers communicate both with the host machine and with each other.
source:
https://docs.docker.com/articles/networking/
You need some bridge to run docker.
If you have another bridge for this, just delete default docker0.
Solution found.
First I configure my bridge0 via init scripts or NetworkManager,then
edit /etc/docker/daemon.json
{
"bridge": "bridge0"
}
I have a docker instance on a host which has two network interfaces, one attached to the internet and one virtual private network.
The host is able to connect to the internet and the VPN.
The docker instance running on the host can connect to the internet, but cannot reach the VPN.
How can I assure my docker instance can connect to the VPN?
I have read explanation about using pipework (https://github.com/jpetazzo/pipework/) but don't see how I can get this to work for me.
I am using docker 0.8.0 on Ubuntu 13.10.
Thanks for the help.
I think that you do not need pipework. In default configuration, you should be able to reach both host interfaces from docker eth0 interface. Possible problems:
DNS: my default container resolv.conf is 8.8.8.8 and it may not know some VPN-specific domain names.
Filtering/firewall at host possibly drops/does not forward packets to VPN. (check firewall f.e ufw status, ...)
You can check IP ranges for possible conflicts in docker networking. In case of conflict, you can configure docker network interface docker0 manually to be ok with your VPN:
/etc/network/interfaces:
auto docker0
iface docker0 inet static
address 192.168.1.1 <--- configure this
netmask 255.255.255.0
bridge_stp off
bridge_fd 0