Installation of ssh-chat on Ubuntu 16.04 server

There are many facts and rumors about the internet surveillance and privacy violations. I have recently found very simple chat solution called ssh-chat. It is written in golang and provides the chatting between multilpe parts in simple terminal opened by standard ssh client. So it benefits from ssh security and any client participant has no need to install any additional software. The author published his ideas in the article: Why aren’t we using SSH for everything?

It can be easily run on your local computer, VPS or dedicated server. Here is the example of installation on Ubuntu 16.04 based server.

Setup

Download the binary or if you have go installed download and compile the code according to instructions here

The instrutions below are run with sudo privileges:

$ sudo bash

Create the special user to own running server with low priviledges

# groupadd -r sshchat && useradd -r -g sshchat -s /usr/sbin/nologin -d /nonexistent sshchat

Generate identity key and prepare whitelist and message of the day file.

# mkdir /etc/sshchat && chgrp sshchat /etc/sshchat && chmod g+s /etc/sshchat 
 
# cd /etc/sshchat && mkdir keys && cd keys

# ssh-keygen -f idkey

# touch whitelist && chmod 640 whitelist
  
# cd .. && cat 'Welcome to chat' > motd.txt

Go to dir with compiled binary and put it to executable location:

# cp ssh-shat /usr/local/bin/ssh-chat

# chgrp sshchat /usr/local/bin/ssh-chat && chmod 750 /usr/local/bin/ssh-chat

Create systemd service

# vim /lib/systemd/system/sshchat.service 

and put there following content:

[Unit]
Description=Ssh Chat Server

Wants=network.target
After=network.target


[Service]
User=sshchat
Group=sshchat


ExecStart=/usr/local/bin/ssh-chat  --bind=":15555" --identity=/etc/sshchat/keys/idkey --whitelist=/etc/sshchat/keys/whitelist --motd=/etc/sshchat/motd.txt


[Install]
WantedBy=multi-user.target

Update systemctl:

systemctl daemon-reload

Create start script that automaticall enables/disables firewall:

# vim /usr/local/bin/schat.sh

with content below:

#!/bin/bash

if [ "$EUID" -ne 0 ]
  then echo "Please run as root"
  exit
fi

case $1 in
    start)
        ufw allow proto tcp from 0.0.0.0/0 to any port 15555
        systemctl start sshchat
        echo "Started"
        ;;

    stop)
        systemctl stop sshchat
        ufw delete allow proto tcp from 0.0.0.0/0 to any port 15555
        echo "Stopped"
        ;;

    status)
        systemctl status sshchat
        ;;
        *)
        echo "Usage: sudo schat.sh start|stop|status"
        ;;
esac

Adding user to whitelist

If you start your server without whitelist option, anybody can connect to your chat server. In order to probide login security each client have to generate own key:

$ ssh-keygen -f chatkey

and then send it's public part (chatkey.pub file) to server owner.

Server owner has to add it to whitelist file like:

# cat chatkey.pub >> /etc/sshchat/keys/whitelist

The client can connect to chat like:

$ ssh chatuser@chatserver -i chatkey 

Usage

To start chat server

$ sudo schat.sh start

To stop chat server

$ sudo schat.sh stop

To get status of server

$ sudo schat.sh status