271 lines
10 KiB
Markdown
271 lines
10 KiB
Markdown
# Fail2Ban Prometheus Exporter
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Go tool to collect and export metrics on Fail2Ban
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## Table of Contents
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1. Introduction
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2. Running the Exporter
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3. Running in Docker
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4. Metrics
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## 1. Introduction
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The exporter can collect metrics from 2 locations: the fail2ban server socket and the fail2ban server database.
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Once the exporter is running, metrics are available at `localhost:9191/metrics`.
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(The default port is `9191` but can be modified with the `-port` flag)
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### 1.1. Socket
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The recommended way to run the exporter is to point it at the fail2ban server socket.
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This allows the exporter to communicate with the server the same way `fail2ban-client` does and ensures the metrics it collects align with the values reported by `fail2ban-client status <jail>`.
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The default path to the socket is: `/var/run/fail2ban/fail2ban.sock`
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### 1.2. Deprecated: Database
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The original way to collect metrics is to read them from the fail2ban database.
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This has now been deprecated in favour of using the socket.
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The reason being that database metrics do not always align with the output of `fail2ban-client status <jail>` and cause confusion.
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See [#11](https://gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/-/issues/11) for more details.
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If necessary, these metrics can still be exported by providing the database path to the exporter.
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The default path to the fail2ban database is: `/var/lib/fail2ban/fail2ban.sqlite3`
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## 2. Running the Exporter
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The exporter is compiled and released as a single binary.
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This makes it very easy to run in any environment.
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No additional runtime dependencies are required.
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Compiled binaries for various platforms are provided in each release.
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See the [releases page](https://gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/-/releases) for more information.
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**Usage**
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```
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$ fail2ban-prometheus-exporter -h
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-db string
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path to the fail2ban sqlite database (deprecated)
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-port int
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port to use for the metrics server (default 9191)
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-socket string
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path to the fail2ban server socket
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-version
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show version info and exit
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-collector.textfile
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enable the textfile collector
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-collector.textfile.directory string
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directory to read text files with metrics from
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```
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**Example**
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```
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fail2ban-prometheus-exporter -socket /var/run/fail2ban/fail2ban.sock -port 9191
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```
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Note that the exporter will need read access to the fail2ban socket or database.
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### 2.1. Compile from Source
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The code can be compiled from source by running `go build` inside the `src/` folder.
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Go version `1.15` or greater is required.
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Run `go mod download` to download all necessary dependencies before running the build.
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## 3. Running in Docker
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If use of docker is desired, an official docker image is available on the Gitlab container registry.
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Use it by pulling the following image:
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```
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registry.gitlab.com/hectorjsmith/fail2ban-prometheus-exporter:latest
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```
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Use the `:latest` tag to get the most up to date code (less stable) or use one of the version tagged images to use a specific release.
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See the [registry page](https://gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/container_registry) for all available tags.
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### 3.1. Volumes
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The docker image is designed to run by mounting either the fail2ban sqlite3 database of the fail2ban run folder.
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- The database should be mounted at: `/app/fail2ban.sqlite3`
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- The run folder should be mounted at: `/var/run/fail2ban`
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Both paths can be mounted with readonly (`ro`) permissions.
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**NOTE:** While it is possible to mount the `fail2ban.sock` file directly, it is recommended to mount the parent folder instead.
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The `.sock` file is deleted by fail2ban on shutdown and re-created on startup and this causes problems for the docker mount.
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See [this reply](https://gitlab.com/hectorjsmith/fail2ban-prometheus-exporter/-/issues/11#note_665003499) for more details.
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### 3.2. Docker run
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Use the following command to run the exporter as a docker container.
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```
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docker run -d \
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--name "fail2ban-exporter" \
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-v /var/lib/fail2ban/fail2ban.sqlite3:/app/fail2ban.sqlite3:ro \
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-v /var/run/fail2ban:/var/run/fail2ban:ro \
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-p "9191:9191" \
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registry.gitlab.com/hectorjsmith/fail2ban-prometheus-exporter:latest
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```
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### 3.3. Docker compose
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The following is a simple docker-compose file to run the exporter.
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```
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version: "2"
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services:
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exporter:
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image: registry.gitlab.com/hectorjsmith/fail2ban-prometheus-exporter:latest
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volumes:
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- /var/lib/fail2ban/fail2ban.sqlite3:/app/fail2ban.sqlite3:ro
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- /var/run/fail2ban/:/var/run/fail2ban:ro
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ports:
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- "9191:9191"
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```
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## 4. Metrics
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Access exported metrics at the `/metrics` path on the configured port.
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**Note on Fail2Ban Jails**
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fail2ban can be configured to process different log files and use different rules for each one.
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These separate configurations are referred to as *jails*.
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For example, fail2ban can be configured to watch the system logs for failed SSH connections and Nextcloud logs for failed logins.
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In this configuration, there will be two jails - one for IPs banned from the SSH logs, and one for IPs banned from the Nextcloud logs.
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This tool exports several metrics *per jail*, meaning that it is possible to track how many IPs are being banned in each jail as well as the overall total.
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This can be useful to track what services are seeing more failed logins.
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### 4.1. Socket-based Metrics
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These are the metrics exported by reading data from the fail2ban server socket.
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All metrics are prefixed with `f2b_`.
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Exposed metrics:
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* `up` - Returns 1 if the fail2ban server is up and connection succeeds
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* `errors` - Number of errors since startup
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* `db` - Errors connecting to the database
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* `socket_conn` - Errors connecting to the fail2ban socket (e.g. connection refused)
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* `socket_req` - Errors sending requests to the fail2ban server (e.g. invalid responses)
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* `jail_count` - Number of jails configured in fail2ban
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* `jail_banned_current` (per jail) - Number of IPs currently banned
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* `jail_banned_total` (per jail) - Total number of banned IPs since fail2ban startup (includes expired bans)
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* `jail_failed_current` (per jail) - Number of current failures
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* `jail_failed_total` (per jail) - Total number of failures since fail2ban startup
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* `version` - Version string of the exporter and fail2ban
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**Sample**
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```
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# HELP f2b_errors Number of errors found since startup
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# TYPE f2b_errors counter
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f2b_errors{type="db"} 0
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f2b_errors{type="socket_conn"} 0
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f2b_errors{type="socket_req"} 0
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# HELP f2b_jail_banned_current Number of IPs currently banned in this jail
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# TYPE f2b_jail_banned_current gauge
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f2b_jail_banned_current{jail="recidive"} 5
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f2b_jail_banned_current{jail="sshd"} 15
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# HELP f2b_jail_banned_total Total number of IPs banned by this jail (includes expired bans)
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# TYPE f2b_jail_banned_total gauge
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f2b_jail_banned_total{jail="recidive"} 6
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f2b_jail_banned_total{jail="sshd"} 31
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# HELP f2b_jail_count Number of defined jails
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# TYPE f2b_jail_count gauge
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f2b_jail_count 2
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# HELP f2b_jail_failed_current Number of current failures on this jail's filter
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# TYPE f2b_jail_failed_current gauge
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f2b_jail_failed_current{jail="recidive"} 5
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f2b_jail_failed_current{jail="sshd"} 6
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# HELP f2b_jail_failed_total Number of total failures on this jail's filter
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# TYPE f2b_jail_failed_total gauge
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f2b_jail_failed_total{jail="recidive"} 7
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f2b_jail_failed_total{jail="sshd"} 125
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# HELP f2b_up Check if the fail2ban server is up
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# TYPE f2b_up gauge
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f2b_up 1
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# HELP f2b_version Version of the exporter and fail2ban server
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# TYPE f2b_version gauge
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f2b_version{exporter="0.3.0",fail2ban="0.11.1"} 1
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```
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The metrics above correspond to the matching fields in the `fail2ban-client status <jail>` command:
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```
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Status for the jail: sshd|- Filter
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| |- Currently failed: 6
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| |- Total failed: 125
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| `- File list: /var/log/auth.log
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`- Actions
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|- Currently banned: 15
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|- Total banned: 31
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`- Banned IP list: ...
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```
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### 4.2. Database Metrics (deprecated)
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These are the original metrics exported by the initial release of the exporter.
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They are all based on the data stored in the fail2ban sqlite3 database.
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*These metrics are deprecated and will be removed in a future release.*
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All metrics are prefixed with `fail2ban_`.
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Exposed metrics:
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* `up` - Returns 1 if the service is up
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* `errors` - Returns the number of errors found since startup
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* `enabled_jails` - Returns 1 for each jail that is enabled, 0 if disabled.
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* `bad_ips` (per jail)
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* A *bad IP* is defined as an IP that has been banned at least once in the past
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* Bad IPs are counted per jail
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* `banned_ips` (per jail)
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* A *banned IP* is defined as an IP that is currently banned on the firewall
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* Banned IPs are counted per jail
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**Sample**
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```
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# HELP fail2ban_bad_ips (Deprecated) Number of bad IPs stored in the database (per jail).
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# TYPE fail2ban_bad_ips gauge
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fail2ban_bad_ips{jail="recidive"} 0
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fail2ban_bad_ips{jail="sshd"} 0
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# HELP fail2ban_banned_ips (Deprecated) Number of banned IPs stored in the database (per jail).
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# TYPE fail2ban_banned_ips gauge
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fail2ban_banned_ips{jail="recidive"} 0
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fail2ban_banned_ips{jail="sshd"} 0
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# HELP fail2ban_enabled_jails (Deprecated) Enabled jails.
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# TYPE fail2ban_enabled_jails gauge
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fail2ban_enabled_jails{jail="recidive"} 1
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fail2ban_enabled_jails{jail="sshd"} 1
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# HELP fail2ban_errors (Deprecated) Number of errors found since startup.
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# TYPE fail2ban_errors counter
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fail2ban_errors{type="db"} 0
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# HELP fail2ban_up (Deprecated) Was the last fail2ban query successful.
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# TYPE fail2ban_up gauge
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fail2ban_up 1
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```
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### 4.3. Textfile Metrics
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For more flexibility the exporter also allows exporting metrics collected from a text file.
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To enable textfile metrics:
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1. Enable the collector with `-collector.textfile=true`
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2. Provide the directory to read files from with the `-collector.textfile.directory` flag
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Metrics collected from these files will be exposed directly alongside the other metrics without any additional processing.
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This means that it is the responsibility of the file creator to ensure the format is correct.
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By exporting textfile metrics an extra metric is also exported with an error count for each file:
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```
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# HELP textfile_error Checks for errors while reading text files
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# TYPE textfile_error gauge
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textfile_error{path="file.prom"} 0
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```
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**NOTE:** Any file not ending with `.prom` will be ignored.
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