I created a 2 node cluster with OS as UBUNTU.
After deploying a container, trying a kubectl exec or logs fail with following error :-

**Error from server: error dialing backend: No SSH tunnels currently open. Were the targets able to accept an ssh-key for user** 

Please tell how to make it work.
Nodes are part of default pool only.
I am trying to do kubectl exec from my laptop which has credentials to cluster.

Output of default firewall :

```
gcloud compute firewall-rules list --filter network=default
default-allow-http                        default  INGRESS    1000      tcp:80
default-allow-https                       default  INGRESS    1000      tcp:443
default-allow-icmp                        default  INGRESS    65534     icmp
default-allow-internal                    default  INGRESS    65534     tcp:0-65535,udp:0-65535,icmp
default-allow-rdp                         default  INGRESS    65534     tcp:3389
default-allow-ssh                         default  INGRESS    65534     tcp:22
gke-ks-gke-test-cluster-0725bebf-all      default  INGRESS    1000      ah,sctp,tcp,udp,icmp,esp
gke-ks-gke-test-cluster-0725bebf-ssh      default  INGRESS    1000      tcp:22
gke-ks-gke-test-cluster-0725bebf-vms      default  INGRESS    1000      icmp,tcp:1-65535,udp:1-65535

```