code-server/doc/fail2ban.md

# Protecting code-server from bruteforce attempts
code-server outputs all failed login attempts, along with the IP address,
provided password, user agent and timestamp by default.

When using a reverse proxy such as Nginx or Apache, the remote address may
appear to be `127.0.0.1` or a similar address so `X-Forwarded-For` should be
used instead. Ensure that you are setting this value in your reverse proxy:

Nginx:
```
location / {
  ...
  proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
  ...
}
```

Apache:
```
<VirtualEnv>
  ...
  SetEnvIf X-Forwarded-For "^.*\..*\..*\..*" forwarded
  ...
</VirtualEnv>
```

It is extremely important that you ensure that your code-server instance is not
accessible from the internet (use localhost or block it in your firewall).

## Fail2Ban
Fail2Ban allows for automatically banning and logging repeated failed
authentication attempts for many applications through regex filters. A working
filter for code-server can be found in `./examples/fail2ban.conf`. Once this
is installed and configured correctly, repeated failed login attempts should
automatically be banned from connecting to your server.