pf

PF Plugin

The pf plugin gathers information from the FreeBSD/OpenBSD pf firewall. Currently it can retrive 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 retrives 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.

Using sudo

You may edit your sudo configuration with the following:

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

Configuration:

  # use sudo to run pfctl
  use_sudo = false

Measurements & Fields:

• pf
  • entries (integer, count)
  • searches (integer, count)
  • inserts (integer, count)
  • removals (integer, count)

Example Output:

> 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

> ./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