# Use a SOCKS5 Proxy to Access the Kubernetes API
LLMS index: [llms.txt](/llms.txt)
---
FEATURE STATE:Kubernetes v1.24 [stable]
This page shows how to use a SOCKS5 proxy to access the API of a remote Kubernetes cluster.
This is useful when the cluster you want to access does not expose its API directly on the public internet.
## Before you begin
You need to have a Kubernetes cluster, and the kubectl command-line tool must
be configured to communicate with your cluster. It is recommended to run this tutorial on a cluster with at least two nodes that are not acting as control plane hosts. If you do not already have a
cluster, you can create one by using
minikube
or you can use one of these Kubernetes playgrounds:
Your Kubernetes server must be at or later than version v1.24.
To check the version, enter kubectl version.
You need SSH client software (the `ssh` tool), and an SSH service running on the remote server.
You must be able to log in to the SSH service on the remote server.
## Task context
Note:
This example tunnels traffic using SSH, with the SSH client and server acting as a SOCKS proxy.
You can instead use any other kind of SOCKS5 proxies.
Figure 1 represents what you're going to achieve in this task.
* You have a client computer, referred to as local in the steps ahead, from where you're going to create requests to talk to the Kubernetes API.
* The Kubernetes server/API is hosted on a remote server.
* You will use SSH client and server software to create a secure SOCKS5 tunnel between the local and
the remote server. The HTTPS traffic between the client and the Kubernetes API will flow over the SOCKS5
tunnel, which is itself tunnelled over SSH.
graph LR;
subgraph local[Local client machine]
client([client])-. local traffic .-> local_ssh[Local SSH SOCKS5 proxy];
end
local_ssh[SSH SOCKS5 proxy]-- SSH Tunnel -->sshd
subgraph remote[Remote server]
sshd[SSH server]-- local traffic -->service1;
end
client([client])-. proxied HTTPs traffic going through the proxy .->service1[Kubernetes API];
classDef plain fill:#ddd,stroke:#fff,stroke-width:4px,color:#000;
classDef k8s fill:#326ce5,stroke:#fff,stroke-width:4px,color:#fff;
classDef cluster fill:#fff,stroke:#bbb,stroke-width:2px,color:#326ce5;
class ingress,service1,service2,pod1,pod2,pod3,pod4 k8s;
class client plain;
class cluster cluster;
Figure 1. SOCKS5 tutorial components
## Using ssh to create a SOCKS5 proxy
The following command starts a SOCKS5 proxy between your client machine and the remote SOCKS server:
```shell
# The SSH tunnel continues running in the foreground after you run this
ssh -D 1080 -q -N username@kubernetes-remote-server.example
```
The SOCKS5 proxy lets you connect to your cluster's API server based on the following configuration:
* `-D 1080`: opens a SOCKS proxy on local port :1080.
* `-q`: quiet mode. Causes most warning and diagnostic messages to be suppressed.
* `-N`: Do not execute a remote command. Useful for just forwarding ports.
* `username@kubernetes-remote-server.example`: the remote SSH server behind which the Kubernetes cluster
is running (eg: a bastion host).
## Client configuration
To access the Kubernetes API server through the proxy you must instruct `kubectl` to send queries through
the `SOCKS` proxy we created earlier. Do this by either setting the appropriate environment variable,
or via the `proxy-url` attribute in the kubeconfig file. Using an environment variable:
```shell
export HTTPS_PROXY=socks5://localhost:1080
```
To always use this setting on a specific `kubectl` context, specify the `proxy-url` attribute in the relevant
`cluster` entry within the `~/.kube/config` file. For example:
```yaml
apiVersion: v1
clusters:
- cluster:
certificate-authority-data: LRMEMMW2 # shortened for readability
server: https://:6443 # the "Kubernetes API" server, in other words the IP address of kubernetes-remote-server.example
proxy-url: socks5://localhost:1080 # the "SSH SOCKS5 proxy" in the diagram above
name: default
contexts:
- context:
cluster: default
user: default
name: default
current-context: default
kind: Config
preferences: {}
users:
- name: default
user:
client-certificate-data: LS0tLS1CR== # shortened for readability
client-key-data: LS0tLS1CRUdJT= # shortened for readability
```
Once you have created the tunnel via the ssh command mentioned earlier, and defined either the environment variable or
the `proxy-url` attribute, you can interact with your cluster through that proxy. For example:
```shell
kubectl get pods
```
```console
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system coredns-85cb69466-klwq8 1/1 Running 0 5m46s
```
Note:
Before kubectl 1.24, most kubectl commands worked when using a socks proxy, except kubectl exec.
kubectl supports both HTTPS_PROXY and https_proxy environment variables. These are used by other
programs that support SOCKS, such as curl. Therefore in some cases it
will be better to define the environment variable on the command line:
HTTPS_PROXY=socks5://localhost:1080 kubectl get pods
When using proxy-url, the proxy is used only for the relevant kubectl context,
whereas the environment variable will affect all contexts.
The k8s API server hostname can be further protected from DNS leakage by using the socks5h protocol name
instead of the more commonly known socks5 protocol shown above. In this case, kubectl will ask the proxy server
(such as an ssh bastion) to resolve the k8s API server domain name, instead of resolving it on the system running
kubectl. Note also that with socks5h, a k8s API server URL like https://localhost:6443/api does not refer
to your local client computer. Instead, it refers to localhost as known on the proxy server (eg the ssh bastion).
## Clean up
Stop the ssh port-forwarding process by pressing `CTRL+C` on the terminal where it is running.
Type `unset https_proxy` in a terminal to stop forwarding http traffic through the proxy.
## Further reading
* [OpenSSH remote login client](https://man.openbsd.org/ssh)