External access to internet from Kubernetes Pods

Question

I'm having troubles with network access from pods. I had installed new Kubernetes cluster with flannel-network plugin, Checking the health of server - good.

I tried to check network via busybox: kubectl run -it --rm --restart=Never busybox -n microservices --image=busybox sh, then ping 8.8.8.8 results in drop.

But ping 8.8.8.8 succeeded when executed from kubectl exec -it kube-flannel-ds-amd64-xxxx -n kube-system (checking network inside flannel pod).

What can it be? I think it can be something with flannel or docker network configuration. But i did not find information about it.

I tried to change iptables configs, reinit cluster, create and changing docker network interfaces.

I have no more ideas, what can I do?

P.S. There is the same server installed before me and their settings and installation procedure are identical. And their connection is good.

Answer 1

I found the solution ...

Check your network interfaces (ifconfig -a cni0). Good config is:

cni0: flags=4163 mtu 1450 inet 10.244.0.1 netmask 255.255.255.0 broadcast 0.0.0.0...

That subnet (10.244.0.0) configured in flannel-deploy.yaml

But, by default, a new server may have:

cni0: flags=4163 mtu 1450 inet 192.168.0.1 netmask 255.255.255.0 broadcast 0.0.0.0...

Change it to:

ifconfig eth0 10.244.0.1 netmask 255.255.255.0 broadcast 0.0.0.0