docker-mailserver/docs/content/config/security/fail2ban.md

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---
title: 'Security | Fail2Ban'
hide:
- toc # Hide Table of Contents for this page
---
Fail2Ban is installed automatically and bans IP addresses for 3 hours after 3 failed attempts in 10 minutes by default.
## Configuration files
If you want to change this, you can easily edit our github example file: [`config-examples/fail2ban-jail.cf`][github-file-f2bjail].
You can do the same with the values from `fail2ban.conf`, e.g `dbpurgeage`. In that case you need to edit: [`config-examples/fail2ban-fail2ban.cf`][github-file-f2bconfig].
The configuration files need to be located at the root of the `/tmp/docker-mailserver/` volume bind (usually `./docker-data/dms/config/:/tmp/docker-mailserver/`).
This following configuration files from `/tmp/docker-mailserver/` will be copied during container startup.
- `fail2ban-jail.cf` -> `/etc/fail2ban/jail.d/user-jail.local`
- `fail2ban-fail2ban.cf` -> `/etc/fail2ban/fail2ban.local`
### Docker-compose config
Example configuration volume bind:
```yaml
volumes:
- ./docker-data/dms/config/:/tmp/docker-mailserver/
```
!!! attention
`docker-mailserver` must be launched with the `NET_ADMIN` capability in order to be able to install the nftables rules that actually ban IP addresses.
Thus either include `--cap-add=NET_ADMIN` in the `docker run` command, or the equivalent in `docker-compose.yml`:
```yaml
cap_add:
- NET_ADMIN
```
## Running fail2ban in a rootless container
[`RootlessKit`][rootless::rootless-kit] is the _fakeroot_ implementation for supporting _rootless mode_ in Docker and Podman. By default RootlessKit uses the [`builtin` port forwarding driver][rootless::port-drivers], which does not propagate source IP addresses.
It is necessary for `fail2ban` to have access to the real source IP addresses in order to correctly identify clients. This is achieved by changing the port forwarding driver to [`slirp4netns`][rootless::slirp4netns], which is slower than `builtin` but does preserve the real source IPs.
### Docker with `slirp4netns` port driver
For [rootless mode][rootless::docker] in Docker, create `~/.config/systemd/user/docker.service.d/override.conf` with the following content:
```
[Service]
Environment="DOCKERD_ROOTLESS_ROOTLESSKIT_PORT_DRIVER=slirp4netns"
```
And then restart the daemon:
```console
$ systemctl --user daemon-reload
$ systemctl --user restart docker
```
!!! note
This changes the port driver for all rootless containers managed by Docker.
Per container configuration is not supported, if you need that consider Podman instead.
### Podman with `slirp4netns` port driver
[Rootless Podman][rootless::podman] requires adding the value `slirp4netns:port_handler=slirp4netns` to the `--network` CLI option, or `network_mode` setting in your `docker-compose.yml`.
You must also add the ENV `NETWORK_INTERFACE=tap0`, because Podman uses a [hard-coded interface name][rootless::podman::interface] for `slirp4netns`.
!!! example
```yaml
services:
mailserver:
network_mode: "slirp4netns:port_handler=slirp4netns"
environment:
- ENABLE_FAIL2BAN=1
- NETWORK_INTERFACE=tap0
...
```
!!! note
`slirp4netns` is not compatible with user-defined networks.
## Manage bans
You can also manage and list the banned IPs with the [`setup.sh`][docs-setupsh] script.
### List bans
```sh
./setup.sh fail2ban
```
### Un-ban
Here `192.168.1.15` is our banned IP.
```sh
./setup.sh fail2ban unban 192.168.1.15
```
[docs-setupsh]: ../setup.sh.md
[github-file-f2bjail]: https://github.com/docker-mailserver/docker-mailserver/blob/master/config-examples/fail2ban-jail.cf
[github-file-f2bconfig]: https://github.com/docker-mailserver/docker-mailserver/blob/master/config-examples/fail2ban-fail2ban.cf
[rootless::rootless-kit]: https://github.com/rootless-containers/rootlesskit
[rootless::port-drivers]: https://github.com/rootless-containers/rootlesskit/blob/v0.14.5/docs/port.md#port-drivers
[rootless::slirp4netns]: https://github.com/rootless-containers/slirp4netns
[rootless::docker]: https://docs.docker.com/engine/security/rootless
[rootless::podman]: https://github.com/containers/podman/blob/v3.4.1/docs/source/markdown/podman-run.1.md#--networkmode---net
[rootless::podman::interface]: https://github.com/containers/podman/blob/v3.4.1/libpod/networking_slirp4netns.go#L264