# PF Input Plugin

The pf plugin gathers information from the FreeBSD/OpenBSD pf
firewall. Currently it can retrieve information about the state table: the
number of current entries in the table, and counters for the number of searches,
inserts, and removals to the table.

The pf plugin retrieves this information by invoking the `pfstat` command. The
`pfstat` command requires read access to the device file `/dev/pf`. You have
several options to permit telegraf to run `pfctl`:

* Run telegraf as root. This is strongly discouraged.
* Change the ownership and permissions for /dev/pf such that the user telegraf runs at can read the /dev/pf device file. This is probably not that good of an idea either.
* Configure sudo to grant telegraf to run `pfctl` as root. This is the most restrictive option, but require sudo setup.
* Add "telegraf" to the "proxy" group as /dev/pf is owned by root:proxy.

## Using sudo

You may edit your sudo configuration with the following:

```sudo
telegraf ALL=(root) NOPASSWD: /sbin/pfctl -s info
```

## Configuration

```toml @sample.conf
# Gather counters from PF
[[inputs.pf]]
  ## PF require root access on most systems.
  ## Setting 'use_sudo' to true will make use of sudo to run pfctl.
  ## Users must configure sudo to allow telegraf user to run pfctl with no password.
  ## pfctl can be restricted to only list command "pfctl -s info".
  use_sudo = false
```

## Metrics

* pf
  * entries (integer, count)
  * searches (integer, count)
  * inserts (integer, count)
  * removals (integer, count)
  * match (integer, count)
  * bad-offset (integer, count)
  * fragment (integer, count)
  * short (integer, count)
  * normalize (integer, count)
  * memory (integer, count)
  * bad-timestamp (integer, count)
  * congestion (integer, count)
  * ip-option (integer, count)
  * proto-cksum (integer, count)
  * state-mismatch (integer, count)
  * state-insert (integer, count)
  * state-limit (integer, count)
  * src-limit (integer, count)
  * synproxy (integer, count)

## Example Output

```text
> pfctl -s info
Status: Enabled for 0 days 00:26:05           Debug: Urgent

State Table                          Total             Rate
  current entries                        2
  searches                           11325            7.2/s
  inserts                                5            0.0/s
  removals                               3            0.0/s
Counters
  match                              11226            7.2/s
  bad-offset                             0            0.0/s
  fragment                               0            0.0/s
  short                                  0            0.0/s
  normalize                              0            0.0/s
  memory                                 0            0.0/s
  bad-timestamp                          0            0.0/s
  congestion                             0            0.0/s
  ip-option                              0            0.0/s
  proto-cksum                            0            0.0/s
  state-mismatch                         0            0.0/s
  state-insert                           0            0.0/s
  state-limit                            0            0.0/s
  src-limit                              0            0.0/s
  synproxy                               0            0.0/s
```

```shell
> ./telegraf --config telegraf.conf --input-filter pf --test
* Plugin: inputs.pf, Collection 1
> pf,host=columbia entries=3i,searches=2668i,inserts=12i,removals=9i 1510941775000000000
```
