schiwagoa/fail2ban-webui
1
0 Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Initial version of fail2ban-webui

Browse Source 
Web interface to view, ban and unban fail2ban IPs on several hosts via
SSH, generalised from the private f2b-web tool.

- Web UI (Flask/Waitress): hosts.yaml, local/OIDC/proxy authentication,
  English/German UI, origin map, optional Loki/Grafana/GeoIP, CLI helpers
- Agent f2b-webctl with install.sh/uninstall.sh (dedicated user + sudo,
  from= restriction, protected networks, manual jail)
- Hardened Docker image, examples, documentation, smoke test, testbed

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
schiwagoaandClaude Opus 5.5 committed 2026-10-25 15:38:17 +01:00
commit 2e3f79236c
44 files changed
+4280
Download Patch File Download Diff File Expand all files Collapse all files

No files matched your search

docs/agent.md
+269
View File
@@ -0,0 +1,269 @@
# Agent – f2b-webctl
Every fail2ban host runs the agent [`f2b-webctl`](../agent/f2b-webctl): a small Python
script (standard library only) started as SSH **forced command** of the web UI's key.
The web UI cannot run anything else on the host.
| Command (sent by the web UI) | Effect |
|---|---|
| `list` | all jails with their banned IPs (JSON) |
| `ban <ip>` | ban permanently in the manual jail (`manual-block`) |
| `unban <jail> <ip>` | unban in one jail |
| `unban-all <ip>` | unban in all jails |
| `version` | agent version |
Never banned, whatever the web UI sends:
- private, loopback, link-local, CGNAT, multicast and reserved ranges
(`10/8`, `172.16/12`, `192.168/16`, `100.64/10`, `127/8`, `169.254/16`, `fc00::/7`, `fe80::/10`, …)
- all addresses of the host itself and the address the web UI connects from
- everything listed in `PROTECTED` in `/etc/f2b-webctl.conf` (e.g. your home IP)
Every action is logged to syslog (facility `auth`, tag `f2b-webctl`), including rejected ones.
## Requirements
| | |
|---|---|
| fail2ban | ≥ 0.11, running (`fail2ban-client ping`) – older versions without `--with-time` work, but without start/end times |
| python3 | ≥ 3.8 |
| sshd | reachable from the web UI host |
| sudo | for the default user `f2bweb` (`apt install sudo`); not needed with `--user root` |
| bash, ssh-keygen | for the installer |
Works on Debian, Ubuntu, Proxmox VE and other systemd or non-systemd Linux systems –
bare metal, VMs, LXC containers (privileged or unprivileged) and Docker hosts.
## Installation
You need the public key printed by `fail2ban-webui keygen` and the address the web UI
connects from (the public IP of the Docker host, or its LAN address).
```bash
# as root on the fail2ban host
git clone https://git.retronerd.at/schiwagoa/fail2ban-webui.git /tmp/fail2ban-webui
cd /tmp/fail2ban-webui/agent
echo 'ssh-ed25519 AAAA… fail2ban-webui' > /tmp/webui.pub
# see what would happen
bash install.sh --key-file /tmp/webui.pub --from 198.51.100.10 --dry-run
# install
bash install.sh --key-file /tmp/webui.pub --from 198.51.100.10
```
Without `git`: download the three files `f2b-webctl`, `install.sh` and `uninstall.sh` from
the `agent/` directory into one directory and run `install.sh` from there.
The installer shows a summary and asks before it changes anything:
```
fail2ban-webui agent 1.0.0 – fail2ban 1.1.0 – web01
script /usr/local/sbin/f2b-webctl
config /etc/f2b-webctl.conf
SSH user f2bweb (will be created)
sudo rule /etc/sudoers.d/f2b-webctl
key file /var/lib/f2bweb/.ssh/authorized_keys
key 256 SHA256:zfwh… (ED25519)
allowed from 198.51.100.10
manual jail manual-block (will be created)
backups /var/backups/fail2ban-webui-agent
```
What it does:
1. backs up every file it is going to change to `--backup-dir`
2. installs `/usr/local/sbin/f2b-webctl` (`root:root 0750`)
3. writes `/etc/f2b-webctl.conf` (kept if it already exists)
4. creates the system user `f2bweb` (home `/var/lib/f2bweb`, no password) and the sudo rule
```
Defaults!/usr/local/sbin/f2b-webctl env_keep += "SSH_ORIGINAL_COMMAND SSH_CLIENT"
f2bweb ALL=(root) NOPASSWD: /usr/local/sbin/f2b-webctl
```
5. adds the key with all restrictions:
```
restrict,from="198.51.100.10",command="sudo -n /usr/local/sbin/f2b-webctl" ssh-ed25519 AAAA… fail2ban-webui
```
6. creates the jail `manual-block` if it does not exist (see below)
7. runs a self test through the same sudo path the web UI uses
Running the installer again is safe: it updates the script, replaces the key entry and
keeps your configuration.
### Options
| Option | Default | Meaning |
|---|---|---|
| `--key-file FILE` / `--key "KEY"` | – | public key of the web UI (required) |
| `--from ADDRESSES` | any | only accept the key from these IPs/networks (comma separated). **Strongly recommended.** |
| `--user NAME` | `f2bweb` | SSH user; `root` works without sudo |
| `--authorized-keys-file PATH` | `~USER/.ssh/authorized_keys` | where the key entry goes – see [managed keys](#hosts-with-managed-authorized_keys) |
| `--manual-jail NAME` | `manual-block` | jail for manual bans |
| `--banaction ACTION` | from `jail.local` | banaction of a newly created manual jail |
| `--protect NETWORKS` | – | additional protected addresses (only when the config file is written) |
| `--no-jail` | – | do not create the manual jail |
| `--force-config` | – | overwrite an existing `/etc/f2b-webctl.conf` |
| `--backup-dir DIR` | `/var/backups/fail2ban-webui-agent` | backups of changed files |
| `--dry-run` | – | only show what would be done |
| `-y`, `--yes` | – | do not ask |
The installer warns when sshd would not read the chosen key file (`AuthorizedKeysFile`),
when `AllowUsers`/`AllowGroups` are set, or when `--user root` meets `PermitRootLogin no`.
## The manual jail
Bans from the web UI go into one jail, `manual-block` by default, with `bantime = -1`
(permanent). If the jail does not exist, the installer creates:
`/etc/fail2ban/filter.d/manual-block.conf`
```ini
# fail2ban-webui: never matches – the jail is only filled via
# "fail2ban-client set manual-block banip <ip>"
[Definition]
failregex = ^FAIL2BAN-WEBUI-NEVER-MATCHES <HOST>$
ignoreregex =
```
`/etc/fail2ban/jail.d/manual-block.local`
```ini
# fail2ban-webui: permanent manual bans from the web UI
[manual-block]
enabled = true
filter = manual-block
backend = polling
logpath = /var/log/fail2ban-manual-block.log
maxretry = 1
bantime = -1
```
The jail uses your default `banaction` from `jail.local`. Bans survive restarts through
the fail2ban database.
An existing jail with that name is never touched – if you already have a jail for manual
bans, pass its name with `--manual-jail`.
### Docker hosts
fail2ban's default actions block in the `INPUT` chain. Traffic to **published Docker
ports** does not pass `INPUT` but `FORWARD` → `DOCKER-USER`, so those bans would not
affect your containers. For a Docker host, create the manual jail with an action that
uses the `DOCKER-USER` chain, e.g. with iptables:
```bash
bash install.sh --key-file /tmp/webui.pub --from 198.51.100.10 \
--banaction "iptables-allports[chain=DOCKER-USER]"
```
Check the result after the first ban:
```bash
iptables -S DOCKER-USER | head
```
If the web UI runs on the same Docker host, use `address: host.docker.internal` in
`hosts.yaml` and allow SSH from the Docker network if a firewall (e.g. UFW) blocks it:
```bash
ufw allow from 172.23.51.0/24 to any port 22 proto tcp comment 'fail2ban-webui'
```
and install the agent with `--from 172.23.51.10`.
### LXC containers
The agent runs inside the container where fail2ban runs – nothing special is needed.
In **unprivileged** containers fail2ban itself must be able to change the container's
firewall (nftables/iptables inside the CT); test with a manual ban:
```bash
fail2ban-client set manual-block banip 203.0.113.1 && nft list ruleset | grep 203.0.113.1
fail2ban-client set manual-block unbanip 203.0.113.1
```
### Hosts with managed authorized_keys
Some tools (Ansible, Keywarden, cloud-init, …) overwrite `~/.ssh/authorized_keys`.
Put the key into a file they do not manage and make sure sshd reads it:
```bash
grep -i '^AuthorizedKeysFile' /etc/ssh/sshd_config /etc/ssh/sshd_config.d/*.conf
# e.g. AuthorizedKeysFile .ssh/authorized_keys .ssh/authorized_keys2
bash install.sh --key-file /tmp/webui.pub --from 198.51.100.10 \
--user root --authorized-keys-file /root/.ssh/authorized_keys2
```
## Configuration – /etc/f2b-webctl.conf
```ini
# fail2ban-webui agent (f2b-webctl) – settings
# Jail used for manual bans from the web UI
MANUAL_JAIL=manual-block
# Addresses/networks that must never be banned (comma separated), e.g. your home IP.
# Private, loopback, link-local and CGNAT ranges are always protected.
PROTECTED=203.0.113.25,2001:db8:1234::/48
# Also protect all addresses of this host and the address of the web UI (yes/no)
PROTECT_OWN_ADDRESSES=yes
PROTECT_CLIENT=yes
```
Changes take effect immediately – the agent reads the file on every call.
## Testing on the host
```bash
# as root, directly
f2b-webctl list | python3 -m json.tool | head -30
f2b-webctl ban 10.0.0.1 # → rejected, protected
# the same path as the web UI (user f2bweb through sudo)
runuser -u f2bweb -- env SSH_ORIGINAL_COMMAND=version sudo -n /usr/local/sbin/f2b-webctl
# what the agent did
journalctl -t f2b-webctl --since today # or: grep f2b-webctl /var/log/auth.log
```
## Update
Run the installer of the new version again with the same options. Your configuration
and the jail are kept; the script and the key entry are replaced.
## Uninstall
```bash
bash uninstall.sh --dry-run
bash uninstall.sh
```
| Option | Meaning |
|---|---|
| `--user NAME` | agent user (default `f2bweb`) |
| `--authorized-keys-file PATH` | file with the key entry |
| `--remove-user` | also delete the user and its home |
| `--remove-jail` | also delete the manual jail – **lifts all manual bans** (they are listed first) |
| `--backup-dir DIR`, `--dry-run`, `--yes` | as for the installer |
## Manual installation
If you prefer to do it by hand, these are all the steps the installer performs:
```bash
install -o root -g root -m 0750 f2b-webctl /usr/local/sbin/f2b-webctl
nano /etc/f2b-webctl.conf # content see above
useradd --system --create-home --home-dir /var/lib/f2bweb --shell /bin/sh f2bweb
usermod -p '*' f2bweb
visudo -f /etc/sudoers.d/f2b-webctl # content see "What it does", step 4
install -d -o f2bweb -g f2bweb -m 700 /var/lib/f2bweb/.ssh
nano /var/lib/f2bweb/.ssh/authorized_keys # line see step 5
chown f2bweb: /var/lib/f2bweb/.ssh/authorized_keys
chmod 600 /var/lib/f2bweb/.ssh/authorized_keys
# manual jail: the two files from "The manual jail", then
touch /var/log/fail2ban-manual-block.log
fail2ban-client reload
```