Access a VM in the same network as the nodes of my cluster from a pod

Question

I have a kubernetes cluster with some nodes and a VM in the same network as the nodes. I need to execute a command via SSH from one of my Pods in this VM. Is it even possible?

I do not control the cluster or the VM, I just have access to them.

Answer 1

Well, this is a network level issue. When you have a kubernetes cluster onthe same network as your target there is a potential issue that might or might not show up - origin IP on the tcp connection. IF your nodes will MASQ/SNAT all of the outgoing traffic then you are fine, but... for a vm in the same domain as kube nodes it might actually be excluded from that MASQ/SNAT. The reason for that is that kube nodes do know how to route traffic based on POD IP cause they have the overlay networking installed (flannel, calico, weave etc.).

To round this up, you need to either have the traffic to your destination node on MASQ/SNAT at some point, or the target node has to be able to route traffic back to your POD, usualy meaning that it needs overlay networking installed (with the exception of setups that are implemented on higher networking level then nodes them selves, like ie. AWS VPC routing tables)