# How to SSH using Node.js

By Zubair Ahmed · Published 2020-09-25
Source: https://www.grizzlybit.dev/blog/how-to-ssh-using-nodejs

I build IoT applications on a daily basis at [RAZRLAB](https://razrlab.com/), and every once in awhile, I do need the internal tools to perform some functions on servers, be it executing commands or forwarding ports. For this, I found a neat little tool `node-ssh` which helps establish ssh tunnels to servers with key authentication.

## Let's get started

Let's create a new folder and set up a fresh `npm` repository

```bash
npm init --y
```

## Install Dependencies

We are going to use the following dependencies:

- [node-ssh](https://www.npmjs.com/package/node-ssh) - an extremely lightweight Promise wrapper for [ssh2](https://github.com/mscdex/ssh2)
- [dotenv](https://www.npmjs.com/package/dotenv) - a zero-dependency module that loads environment variables from a .env file into process.env

## Environment Variables

We will create our SSH tunnel using private key authentication for that we will create SSH key pair with a passphrase.

I would recommend using your cloud providers SSH key access management to securely manage access to your servers. Read [DigitalOcean's guide to managing SSH key access](https://www.digitalocean.com/docs/droplets/how-to/add-ssh-keys/to-account/).

Now, let's specify paths and information in the `.env` file

```bash
# .env

SSH_host=
SSH_user=
SSH_privatekey=
SSH_passphrase=
```

Environment variable definitions:

- `SSH_host` : Host IP Address or DNS name of the server
- `SSH_user` : Host username for logging in
- `SSH_privatekey` : path to the private key
- `SSH_passphrase` : passphrase for the key for added layer of security

## Test Setup

We will access the server and install a [Redis](https://redis.io/) server. We will use an Ubuntu machine and leverage the `apt` package manager to install the Redis server.

- SSH as we always do 😁

```bash
ssh <username>@<host>
```

- Install Redis Server

```bash
sudo apt-get install redis-server
```

This will download and install Redis and its dependencies. It will also export a CLI application called `redis-cli` to interact with the Redis server.

## Let's go

Now, that we have done the setup. Let's write a minimal client that will navigate to a directory and access the redis-cli to ping [Redis](https://redis.io/) server

```jsx
const node_ssh = require('node-ssh');
const ssh = new node_ssh();

require('dotenv').config();

ssh
  .connect({
    host: process.env.SSH_host,
    username: process.env.SSH_user,
    privateKey: process.env.SSH_privatekey,
    passphrase: process.env.SSH_passphrase,
  })
  .then(() => {
    ssh.execCommand('redis-cli ping', { cwd: '/var/www' }).then((result) => {
      console.log('STDOUT: ' + result.stdout);
      console.log('STDERR: ' + result.stderr);
    });
  });
```

As you can see in the example above, we read the output from STDOUT and STDERR for output and errors respectively, after running the ping command through `redis-cli`.
The neat thing about `node-ssh`, is that it is a simple Promise wrapper and hence you can use `async/await` logic with it.

```jsx
STDOUT: PONG;
```

Now, that you have been able to SSH to a remote server and have been able to run CLI commands, the next step would be to go crazy 😝. You now have endless possibilities of automating deployments and executing commands on your servers leveraging the power of building complex applications using Node.js.

Happy Grizzly Coding 🐻 !