wetty

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Introduction

This is an A to Z guide that will help you get wetty up and running on Debian Stable. It covers the key configuration areas using copy and paste commands to help you install this application and get it securely up and running. It should also provide enough information to allow you to understand extend that configuration for your personal requirements.

Required dependencies

You will need the package build-essential to be installed. We need this specifically for node-gyp to build packages when using npm or yarn.

As the root user run these commands:

apt update
apt install -y build-essential

If you do not have root access and just want to check the dependency is installed you can use this command:

dpkg -s build-essential | grep Status:

If the program is installed you will see this result:

Status: install ok installed

Create a local user account

For this guide, unless specifically stated, you should not use a root account to install and run wetty. Please use an existing local account or create one.

Note: Whichever user runs wetty should be the same user you wish to authenticate with via ssh to keep this simple.

If you need to create a local user account you can run this command:

Important note: replace username with a user name of your choosing and create a password when prompted

adduser --gecos "" username

Switch to your local user now and open an ssh session to continue with this guide.

Install node locally

To install and manage node as a local user we are going to use Node Version Manager as an established solution to installing and managing multiple versions of node without needing root access. We are going to install the lts or long term support release of node to use with this application.

bash <(curl -s https://raw.githubusercontent.com/nvm-sh/nvm/master/install.sh) && source ~/.profile
nvm install --lts

You can now call node to check it works using this command.

node -v

Your result should look something like this.

v12.16.2

Note: There is consideration with this method. node is only in the local user's path through sourcing of the ~/.nvm/nvm.sh via the users .bashrc file. Unless this is done node will not be usable unless directly linked to and nvm commands will be unavailable.

The way we over come this issue for the needs of this guide is by using this command where applicable:

source ~/.nvm/nvm.sh && nvm which 12

Why? This command will always provide us with the path to the most current version of node 12 installed via nvm regardless of other versions of node installed.

Generate openssl certificates.

Why? So that later we can configure wetty to work with https and make sure we interact with wetty over a secure connection at all times.

Make the required directory using this command:

mkdir -p ~/.ssl

Generate the self signed openssl certificates we will use to encrypt our web traffic when using wetty using this command:

Note: we are usingecdsa using the secp521r1 curve.

openssl req -x509 -nodes -days 1095 -newkey ec:<(openssl ecparam -name secp521r1) -subj "/C=GB/ST=None/L=None/O=None/OU=None/CN=None" -out ~/.ssl/wetty.crt -keyout ~/.ssl/wetty.key

Now give these file and folders the correct permissions using these commands:

chmod 700 ~/.ssl
chmod 644 ~/.ssl/wetty.crt 
chmod 600 ~/.ssl/wetty.key

This is all we need to do for now in regards to https.

Generate the ssh key file

Why? So that later we can set up automatic login via ssh. Our instance will authorise using this key file stored locally.

Make the required directory, if it does not exist, using this command:

mkdir -p ~/.ssh

Create the ssh private key using ed25519 that we need to authorise our local connection, using this command:

ssh-keygen -q -C "wetty-keyfile" -t ed25519 -N '' -f ~/.ssh/wetty 2>/dev/null <<< y >/dev/null

Important Note: You must add the public key to your authorized_keys file in order to be able to log in using your ssh key file when accessing wetty via a web browser.

Copy the key to our ~/.ssh/authorized_keys file, using this command:

cat ~/.ssh/wetty.pub >> ~/.ssh/authorized_keys

Now give these file the correct permissions, using these commands:

chmod 700 ~/.ssh
chmod 644 ~/.ssh/authorized_keys
chmod 600 ~/.ssh/wetty

Optional: A housekeeping command. If you need to remove all entries of the wetty public key with the comment wetty-keyfile from the ~/.ssh/authorized_keys file use this command. Otherwise ignore this.

sed -r '/^ssh-ed25519(.*)wetty-keyfile$/d' -i ~/.ssh/authorized_keys

Install wetty

Note: we are using -g for npm or global for yarn along with --prefix ~/ so that the application symbolic link is installed to our ~/bin directory and available in our local user's PATH.

As your local use run these commands to install wetty and forever. We will need forever later to run wetty in in the background.

First, we need to make sure the local user ~/bin folder exists and is in the PATH for the following commands to work.

mkdir -p ~/bin && source ~/.profile

Please use either the npm or yarn method and not both. The yarn method is recommended but I provide both as you may have a personal preference. The outcome is effectively the same.

npm - optional - use npm to install wetty

npm install -g wetty forever --prefix ~/

yarn - recommended - use yarn to install wetty

npm install -g yarn --prefix ~/
yarn global add wetty forever --prefix ~/

Once successfully installed the application should be available in your local user's PATH. To test the installation was successful please use this command:

wetty -h

Accessing the web interface.

This needs to be clarified here because it is not easy to do in the next steps if wetty is running in the terminal.

This command will generate the correct URL you need to visit after using the start up commands in the following section.

echo https://$(curl -s4 icanhazip.com):3000

Please make make a note of this URL now.

Running wetty

Now we have all the ground work done we can focus on our wetty server configuration settings.

For example, the below command would provide a https instance with automatic ssh authorisation using our wetty private key on port 3000 accessible at https://IP:3000 . Refer to the previous URL generation command.

Important note: This command will run in your current terminal session and not in the background.

wetty --host 0.0.0.0 -p 3000 --title wetty --base / --sshkey ~/.ssh/wetty --sshhost localhost --sshuser $(whoami) --sshport 22 --sshauth publickey --sslkey ~/.ssl/wetty.key --sslcert ~/.ssl/wetty.crt

forever to manage wetty

Now you can use forever we installed to run wetty in the background instead of directly in your terminal

forever start ~/bin/wetty --host 0.0.0.0 -p 3000 --title wetty --base / --sshkey ~/.ssh/wetty --sshhost localhost --sshuser $(whoami) --sshport 22 --sshauth publickey --sslkey ~/.ssl/wetty.key --sslcert ~/.ssl/wetty.crt

To stop wetty from running you can use this command

forever stop ~/bin/wetty

Optional - config file.

Important Note: This is an optional and unsupported method to load settings from a physical configuration file. It's a hack and you need to accept it has some limitations but I've made it as easy as I can to use.

Since wetty does not have configurations files and all commands are passed as command line arguments we can fake this behaviour by using a method to read from a text file and expand variables then pass this to wetty. All arguments must be on a single line

Create a directory to store our configuration data using this command:

mkdir -p ~/.config/wetty

Now populate our config file with some settings. This examples is the same command as above.

echo -n '--host 0.0.0.0 -p 3000 --title wetty --base / --sshkey ~/.ssh/wetty --sshhost localhost --sshuser $(whoami) --sshport 22 --sshauth publickey --sslkey ~/.ssl/wetty.key --sslcert ~/.ssl/wetty.crt' > ~/.config/wetty/config

This configuration file is now available here for you to manage your settings.

~/.config/wetty/config

Now we can load this file as part of the command we pass to wetty with shell expansion and command substitution.

wetty $(eval echo $(cat ~/.config/wetty/config))

forever using a config file

Now you can use forever to run it in the background instead of directly in your terminal

forever start ~/bin/wetty $(eval echo $(cat ~/.config/wetty/config))

To stop wetty from running you can use this command

forever stop ~/bin/wetty

Environment settings explained

Let's break it down so that we can understand what's being done and why.

--host 0.0.0.0 -p 3000 --title wetty --base /

--host 0.0.0.0 - defines the interface we want to bind to. Using 0.0.0.0 means that we bind to all available interfaces so using this setting just works. When we use nginx we can change this to --host 127.0.0.1 in order to prevent generic port access to the application and force traffic through our nginx reverse proxy URL.

-p 3000 - defines the local listening port. You will use this port to connect via the remotely accessible web server or when configuring a reverse proxy through nginx.

--title wetty - an optional setting to set the window title for this wetty session.

--base / - changes the default base URL setting from /wetty/ to define the remote URL. We use --base / to make wetty accessible on the URL format https://IP:3000 instead of https://IP:3000/wetty but we would change this back if we use nginx to reverse proxy the application.

SSH settings explained

These settings are all specific to ssh and will enable you to automatically log into you ssh session for the selected user.

--sshkey ~/.ssh/wetty --sshhost localhost --sshuser $(whoami) --sshport 22 --sshauth publickey

--sshkey ~/.ssh/wetty - we are telling wetty to load our ssh key file that we generated earlier.

--sshhost localhost - optional setting telling wetty to connect the host localhost

--sshuser $(whomai) - defines our ssh username. In this case via the command substitution of whoami which will not require your input of a username.

--sshport 22 - optional setting to set the ssh port we need to connect to.

--sshauth publickey defines the accepted authentication types. You do not have to use the key file and you can instead require a password but setting this to --sshauth password. You can specify both --sshauth publickey,password

SSL settings explained

These settings are specific to openssl to make wetty load https webserver so that all data is transmitted over a secure connection.

--sslkey ~/.ssl/wetty.key --sslcert ~/.ssl/wetty.crt

--sslkey ~/.ssl/wetty.key - tells wetty to load our openssl generated key file.

--sslcert ~/.ssl/wetty.crt - tells wetty to load our openssl generates certificate file.

Systemd service settings

We will use a local user systemd service file to manage the wetty service.

First, create the required directory, if it does not exist.

mkdir -p ~/.config/systemd/user

Systemd service.

Here is a normal service file template with hardcoded values you can insert into the wetty.service file.

Use nano to open the file for editing.

nano ~/.config/systemd/user/wetty.service

The copy and paste this code.

[Unit]
Description=wetty
After=network.target

[Service]
Type=simple
WorkingDirectory=%h
ExecStart=/bin/bash -c "$$(source /home/$$(whoami)/.nvm/nvm.sh && nvm which 12) /home/$$(whoami)/bin/wetty --host 0.0.0.0 -p 3000 --title wetty --base / --sshkey /home/$$(whoami)/.ssh/wetty --sshhost localhost --sshuser $$(whoami) --sshport 22 --sshauth publickey --sslkey /home/$$(whoami)/.ssl/wetty.key --sslcert /home/$$(whoami)/.ssl/wetty.crt"
TimeoutStopSec=20
KillMode=mixed
Restart=always
RestartSec=2

[Install]
WantedBy=multi-user.target

Press ctrl + x and then press y to save then press enter to confirm and exit nano.

Optional - Systemd service with config file

Here is the example using our pseudo configuration file. All modifications to the start up of wetty will be done by editing the ~/.config/Wetty/config file and then reloading the wetty.service.

Use nano to open the file for editing.

nano ~/.config/systemd/user/wetty.service

The copy and paste this code.

[Unit]
Description=wetty
After=network.target

[Service]
Type=simple
WorkingDirectory=%h
ExecStart=/bin/bash -c "$$(source /home/$$(whoami)/.nvm/nvm.sh && nvm which 12) /home/$$(whoami)/bin/wetty $$(eval echo $(cat /home/$$(whoami)/.config/wetty/config))"
TimeoutStopSec=20
KillMode=mixed
Restart=always
RestartSec=2

[Install]
WantedBy=multi-user.target

Press ctrl + x and then press y to save then press enter to confirm and exit nano.

Activating your service

The you can enable and start your service.

systemctl --user enable --now wetty

Managing your services

These commands will help you manage your service.

systemctl --user daemon-reload
systemctl --user status wetty
systemctl --user start wetty
systemctl --user stop wetty
systemctl --user restart wetty
systemctl --user disable --now wetty
systemctl --user enable --now wetty

Nginx reverse proxy

If you want to use nginx as a revers proxy here is the configuration file you can use.

Please modify these specific environment settings:

Why? This will disable generic port access to the application and force traffic via the nginx reverse proxy.

--host 127.0.0.1

Why? This change is so that our application does not attempt to load as the web root of / for nginx.

--base /wetty

Now you can use this nginx configuration file.

Note: we are using https here https://127.0.0.1:3000/wetty; because we configured wetty to run via https

The copy and paste this into the https server block of your enable server configuration file.

location /wetty {
    proxy_pass https://127.0.0.1:3000/wetty;
    #
    proxy_pass_request_headers on;
    #
    proxy_set_header Host $host;
    #
    proxy_http_version 1.1;
    #
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $scheme;
    proxy_set_header X-Forwarded-Protocol $scheme;
    proxy_set_header X-Forwarded-Host $http_host;
    proxy_set_header X-NginX-Proxy true;
    #
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection $http_connection;
    proxy_read_timeout 43200000;
    proxy_set_header X-Forwarded-Ssl on;
    #
    proxy_redirect off;
    proxy_buffering off;
}

Press ctrl + x and then press y to save then press enter to confirm and exit nano

Now you would need to reload nginx service using this command:

systemctl restart nginx

Accessing the web interface via nginx

Visit the URL format https://YourIP/wetty and you can access wetty. This command will generate the correct URL you need to visit.

echo https://$(curl -s4 icanhazip.com)/wetty

Configuration reference

wetty -h configuration options for reference.

  --help, -h      Print help message                                   [boolean]
  --version       Show version number                                  [boolean]
  --sslkey        path to SSL key                                       [string]
  --sslcert       path to SSL certificate                               [string]
  --sshhost       ssh server host                [string] [default: "localhost"]
  --sshport       ssh server port                         [number] [default: 22]
  --sshuser       ssh user                                [string] [default: ""]
  --title         window title [string] [default: "WeTTy - The Web Terminal Emulator"]
  --sshauth       defaults to "password", you can use "publickey,password" instead[string] [default: "password"]
  --sshpass       ssh password                                          [string]
  --sshkey        path to an optional client private key (connection will be password-less and insecure!) [string]
  --forcessh      Connecting through ssh even if running as root [boolean] [default: false]
  --base, -b      base path to wetty               [string] [default: "/wetty/"]
  --port, -p      wetty listen port                     [number] [default: 3000]
  --host          wetty listen host                [string] [default: "0.0.0.0"]
  --command, -c   command to run in shell            [string] [default: "login"]
  --bypasshelmet  disable helmet from placing security restrictions [boolean] [default: false]

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