Matrix is easy-to-use, decentralized and encrypted private chat software. Matrix is federated, meaning that with a Matrix account on any server, including your own, you can talk to any other Matrix account on the internet, similar to email. Matrix also allows fully end-to-end encrypted group chats.

Synapse is the name of the default Matrix server. It is written in Python.

## Installation

Synapse is not in the Debian package repositories by default, but we can easily add Matrix's repository including it:

    apt install -y lsb-release wget apt-transport-https
    wget -O /usr/share/keyrings/matrix-org-archive-keyring.gpg https://packages.matrix.org/debian/matrix-org-archive-keyring.gpg
    echo "deb [signed-by=/usr/share/keyrings/matrix-org-archive-keyring.gpg] https://packages.matrix.org/debian/ $(lsb_release -cs) main" > /etc/apt/sources.list.d/matrix-org.list

After we update our packages lists, we will be able to install Synapse with `apt`.

    apt update
    apt install matrix-synapse-py3

When prompted, give your main domain name (not a subdomain). This will be the domain appended to your Matrix address, e.g. `@chad:landchad.net`.

## Nginx configuration

Create an Nginx configuration file for Matrix, say `/etc/nginx/sites-available/matrix` and add the content below:

    server {
             server_name matrix.example.org ;
            listen 80;
            listen [::]:80;
            location / {
                    proxy_pass http://localhost:8008;
            }
            location ~* ^(\/_matrix|\/_synapse\/client) {
                    proxy_pass http://localhost:8008;
                    proxy_set_header X-Forwarded-For $remote_addr;
                    client_max_body_size 50M ;
            }
            location /.well-known/matrix/server {
                    return 200 '{"m.homeserver": {"base_url": "https://matrix.example.org"}}';
                    default_type application/json;
                    add_header Access-Control-Allow-Origin *;
            }
    }

Note the `client_max_body_size` variable. By default, Nginx caps the size of files it can transfer. We increase that to 50M if needed by Matrix. (Note however that both Matrix and Nginx have seperate settings for this and to raise it to something much larger, you will have to increase the value in both congfiguration files.)

Now let's enable the Nginx Matrix site and reload Nginx to make it active.

    ln -s /etc/nginx/sites-available/matrix /etc/nginx/sites-enabled
    systemctl reload nginx

### Encryption

Obviously, we need to encrypt our `matrix` subdomain as well. Let's do that with certbot:

    certbot --nginx -d matrix.example.org

## Configuration

The configuration file for Matrix is in `/etc/matrix-synapse/homeserver.yaml`. It is well documented and commented, so you can read about the settings, but let's change the essential ones here.

This article isn't finished. Deal with basic settings and registering accounts.