130 lines
4.6 KiB
Markdown
130 lines
4.6 KiB
Markdown
# ACME
|
|
|
|
Synapse v1.0 will require valid TLS certificates for communication between
|
|
servers (port `8448` by default) in addition to those that are client-facing
|
|
(port `443`). If you do not already have a valid certificate for your domain,
|
|
the easiest way to get one is with Synapse's new ACME support, which will use
|
|
the ACME protocol to provision a certificate automatically. Synapse v0.99.0+
|
|
will provision server-to-server certificates automatically for you for free
|
|
through [Let's Encrypt](https://letsencrypt.org/) if you tell it to.
|
|
|
|
In the case that your `server_name` config variable is the same as
|
|
the hostname that the client connects to, then the same certificate can be
|
|
used between client and federation ports without issue.
|
|
|
|
For a sample configuration, please inspect the new ACME section in the example
|
|
generated config by running the `generate-config` executable. For example:
|
|
|
|
```
|
|
~/synapse/env3/bin/generate-config
|
|
```
|
|
|
|
You will need to provide Let's Encrypt (or another ACME provider) access to
|
|
your Synapse ACME challenge responder on port 80, at the domain of your
|
|
homeserver. This requires you to either change the port of the ACME listener
|
|
provided by Synapse to a high port and reverse proxy to it, or use a tool
|
|
like `authbind` to allow Synapse to listen on port 80 without root access.
|
|
(Do not run Synapse with root permissions!) Detailed instructions are
|
|
available under "ACME setup" below.
|
|
|
|
If you are already using self-signed certificates, you will need to back up
|
|
or delete them (files `example.com.tls.crt` and `example.com.tls.key` in
|
|
Synapse's root directory), Synapse's ACME implementation will not overwrite
|
|
them.
|
|
|
|
You may wish to use alternate methods such as Certbot to obtain a certificate
|
|
from Let's Encrypt, depending on your server configuration. Of course, if you
|
|
already have a valid certificate for your homeserver's domain, that can be
|
|
placed in Synapse's config directory without the need for any ACME setup.
|
|
|
|
## ACME setup
|
|
|
|
The main steps for enabling ACME support in short summary are:
|
|
|
|
1. Allow Synapse to listen for incoming ACME challenges.
|
|
1. Enable ACME support in `homeserver.yaml`.
|
|
1. Move your old certificates (files `example.com.tls.crt` and `example.com.tls.key` out of the way if they currently exist at the paths specified in `homeserver.yaml`.
|
|
1. Restart Synapse.
|
|
|
|
Detailed instructions for each step are provided below.
|
|
|
|
### Listening on port 80
|
|
|
|
In order for Synapse to complete the ACME challenge to provision a
|
|
certificate, it needs access to port 80. Typically listening on port 80 is
|
|
only granted to applications running as root. There are thus two solutions to
|
|
this problem.
|
|
|
|
#### Using a reverse proxy
|
|
|
|
A reverse proxy such as Apache or nginx allows a single process (the web
|
|
server) to listen on port 80 and proxy traffic to the appropriate program
|
|
running on your server. It is the recommended method for setting up ACME as
|
|
it allows you to use your existing webserver while also allowing Synapse to
|
|
provision certificates as needed.
|
|
|
|
For nginx users, add the following line to your existing `server` block:
|
|
|
|
```
|
|
location /.well-known/acme-challenge {
|
|
proxy_pass http://localhost:8009/;
|
|
}
|
|
```
|
|
|
|
For Apache, add the following to your existing webserver config:
|
|
|
|
```
|
|
ProxyPass /.well-known/acme-challenge http://localhost:8009/.well-known/acme-challenge
|
|
```
|
|
|
|
Make sure to restart/reload your webserver after making changes.
|
|
|
|
Now make the relevant changes in `homeserver.yaml` to enable ACME support:
|
|
|
|
```
|
|
acme:
|
|
enabled: true
|
|
port: 8009
|
|
```
|
|
|
|
|
|
#### Authbind
|
|
|
|
`authbind` allows a program which does not run as root to bind to
|
|
low-numbered ports in a controlled way. The setup is simpler, but requires a
|
|
webserver not to already be running on port 80. **This includes every time
|
|
Synapse renews a certificate**, which may be cumbersome if you usually run a
|
|
web server on port 80. Nevertheless, if you're sure port 80 is not being used
|
|
for any other purpose then all that is necessary is the following:
|
|
|
|
Install `authbind`. For example, on Debian/Ubuntu:
|
|
|
|
```
|
|
sudo apt-get install authbind
|
|
```
|
|
|
|
Allow `authbind` to bind port 80:
|
|
|
|
```
|
|
sudo touch /etc/authbind/byport/80
|
|
sudo chmod 777 /etc/authbind/byport/80
|
|
```
|
|
|
|
When Synapse is started, use the following syntax:
|
|
|
|
```
|
|
authbind --deep <synapse start command>
|
|
```
|
|
|
|
Make the relevant changes in `homeserver.yaml` to enable ACME support:
|
|
|
|
```
|
|
acme:
|
|
enabled: true
|
|
```
|
|
|
|
### (Re)starting synapse
|
|
|
|
Ensure that the certificate paths specified in `homeserver.yaml` (`tls_certificate_path` and `tls_private_key_path`) do not currently point to any files. Synapse will not provision certificates if files exist, as it does not want to overwrite existing certificates.
|
|
|
|
Finally, start/restart Synapse. |