Iptables Input Plugin

This plugin gathers packets and bytes counters for rules within a set of table and chain from the Linux's iptables firewall.

[!IMPORTANT] Rules are identified through associated comment, so you must ensure that the rules you want to monitor do have a unique comment using the --comment flag when adding them. Rules without comments are ignored.

The rule number cannot be used as identifier as it is not constant and may vary when rules are inserted/deleted at start-up or by automatic tools (interactive firewalls, fail2ban, ...).

[!IMPORTANT] The iptables command requires CAP_NET_ADMIN and CAP_NET_RAW capabilities. Check the permissions section for ways to grant them.

⭐ Telegraf v1.1.0 🏷️ network, system 💻 linux

Global configuration options <!-- @/docs/includes/plugin_config.md -->

Plugins support additional global and plugin configuration settings for tasks such as modifying metrics, tags, and fields, creating aliases, and configuring plugin ordering. See CONFIGURATION.md for more details.

Configuration

# Gather packets and bytes throughput from iptables
# This plugin ONLY supports Linux
[[inputs.iptables]]
  ## iptables require root access on most systems.
  ## Setting 'use_sudo' to true will make use of sudo to run iptables.
  ## Users must configure sudo to allow telegraf user to run iptables with
  ## no password.
  ## iptables can be restricted to only list command "iptables -nvL".
  # use_sudo = false

  ## Setting 'use_lock' to true runs iptables with the "-w" option.
  ## Adjust your sudo settings appropriately if using this option
  ## ("iptables -w 5 -nvl")
  # use_lock = false

  ## Define an alternate executable, such as "ip6tables". Default is "iptables".
  # binary = "ip6tables"
  ## defines the table to monitor:
  table = "filter"

  ## defines the chains to monitor.
  ## NOTE: iptables rules without a comment will not be monitored.
  ## Read the plugin documentation for more information.
  chains = [ "INPUT" ]

Permissions

The iptables command requires CAP_NET_ADMIN and CAP_NET_RAW capabilities. You have several options to grant permissions to telegraf:

• Run telegraf as root. This is strongly discouraged.
• Configure systemd to run telegraf with CAP_NET_ADMIN and CAP_NET_RAW. This is the simplest and recommended option.
• Configure sudo to grant telegraf to run iptables. This is the most restrictive option, but require sudo setup.

Using systemd capabilities

You may run systemctl edit telegraf.service and add the following:

[Service]
CapabilityBoundingSet=CAP_NET_RAW CAP_NET_ADMIN
AmbientCapabilities=CAP_NET_RAW CAP_NET_ADMIN

Since telegraf will fork a process to run iptables, AmbientCapabilities is required to transmit the capabilities bounding set to the forked process.

Using sudo

To use sudo set the use_sudo option to true and update your sudoers file:

$ visudo
# Add the following line:
Cmnd_Alias IPTABLESSHOW = /usr/bin/iptables -nvL *
telegraf  ALL=(root) NOPASSWD: IPTABLESSHOW
Defaults!IPTABLESSHOW !logfile, !syslog, !pam_session

Using IPtables lock feature

Defining multiple instances of this plugin in telegraf.conf can lead to concurrent IPtables access resulting in "ERROR in input [inputs.iptables]: exit status 4" messages in telegraf.log and missing metrics. Setting 'use_lock = true' in the plugin configuration will run IPtables with the '-w' switch, allowing a lock usage to prevent this error.

Metrics

• iptables
  • tags:
    • table
    • chain
    • ruleid (comment associated to the rule)
  • fields:
    • pkts (integer, count)
    • bytes (integer, bytes)

Example Output

iptables -nvL INPUT

Chain INPUT (policy DROP 0 packets, 0 bytes)
pkts bytes target     prot opt in     out     source               destination
100   1024   ACCEPT     tcp  --  *      *       192.168.0.0/24       0.0.0.0/0            tcp dpt:22 /* ssh */
 42   2048   ACCEPT     tcp  --  *      *       192.168.0.0/24       0.0.0.0/0            tcp dpt:80 /* httpd */

iptables,table=filter,chain=INPUT,ruleid=ssh pkts=100i,bytes=1024i 1453831884664956455
iptables,table=filter,chain=INPUT,ruleid=httpd pkts=42i,bytes=2048i 1453831884664956455