121 lines
4.1 KiB
Markdown
121 lines
4.1 KiB
Markdown
# Iptables Input Plugin
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The iptables plugin gathers packets and bytes counters for rules within a set
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of table and chain from the Linux's iptables firewall.
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Rules are identified through associated comment. **Rules without comment are
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ignored**. Indeed we need a unique ID for the rule and the rule number is not
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a constant: it may vary when rules are inserted/deleted at start-up or by
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automatic tools (interactive firewalls, fail2ban, ...). Also when the rule set
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is becoming big (hundreds of lines) most people are interested in monitoring
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only a small part of the rule set.
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Before using this plugin **you must ensure that the rules you want to monitor
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are named with a unique comment**. Comments are added using the `-m comment
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--comment "my comment"` iptables options.
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The iptables command requires CAP_NET_ADMIN and CAP_NET_RAW capabilities. You
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have several options to grant telegraf to run iptables:
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* Run telegraf as root. This is strongly discouraged.
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* Configure systemd to run telegraf with CAP_NET_ADMIN and CAP_NET_RAW. This is
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the simplest and recommended option.
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* Configure sudo to grant telegraf to run iptables. This is the most
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restrictive option, but require sudo setup.
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## Using systemd capabilities
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You may run `systemctl edit telegraf.service` and add the following:
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```shell
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[Service]
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CapabilityBoundingSet=CAP_NET_RAW CAP_NET_ADMIN
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AmbientCapabilities=CAP_NET_RAW CAP_NET_ADMIN
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```
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Since telegraf will fork a process to run iptables, `AmbientCapabilities` is
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required to transmit the capabilities bounding set to the forked process.
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## Using sudo
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You will need the following in your telegraf config:
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```toml
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[[inputs.iptables]]
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use_sudo = true
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```
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You will also need to update your sudoers file:
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```bash
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$ visudo
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# Add the following line:
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Cmnd_Alias IPTABLESSHOW = /usr/bin/iptables -nvL *
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telegraf ALL=(root) NOPASSWD: IPTABLESSHOW
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Defaults!IPTABLESSHOW !logfile, !syslog, !pam_session
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```
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## Using IPtables lock feature
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Defining multiple instances of this plugin in telegraf.conf can lead to
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concurrent IPtables access resulting in "ERROR in input [inputs.iptables]: exit
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status 4" messages in telegraf.log and missing metrics. Setting 'use_lock =
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true' in the plugin configuration will run IPtables with the '-w' switch,
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allowing a lock usage to prevent this error.
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## Configuration
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```toml @sample.conf
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# Gather packets and bytes throughput from iptables
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[[inputs.iptables]]
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## iptables require root access on most systems.
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## Setting 'use_sudo' to true will make use of sudo to run iptables.
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## Users must configure sudo to allow telegraf user to run iptables with
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## no password.
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## iptables can be restricted to only list command "iptables -nvL".
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use_sudo = false
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## Setting 'use_lock' to true runs iptables with the "-w" option.
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## Adjust your sudo settings appropriately if using this option
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## ("iptables -w 5 -nvl")
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use_lock = false
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## Define an alternate executable, such as "ip6tables". Default is "iptables".
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# binary = "ip6tables"
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## defines the table to monitor:
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table = "filter"
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## defines the chains to monitor.
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## NOTE: iptables rules without a comment will not be monitored.
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## Read the plugin documentation for more information.
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chains = [ "INPUT" ]
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```
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## Measurements & Fields
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* iptables
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* pkts (integer, count)
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* bytes (integer, bytes)
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## Tags
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* All measurements have the following tags:
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* table
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* chain
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* ruleid
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The `ruleid` is the comment associated to the rule.
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## Example Output
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```text
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$ iptables -nvL INPUT
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Chain INPUT (policy DROP 0 packets, 0 bytes)
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pkts bytes target prot opt in out source destination
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100 1024 ACCEPT tcp -- * * 192.168.0.0/24 0.0.0.0/0 tcp dpt:22 /* ssh */
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42 2048 ACCEPT tcp -- * * 192.168.0.0/24 0.0.0.0/0 tcp dpt:80 /* httpd */
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```
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```shell
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$ ./telegraf --config telegraf.conf --input-filter iptables --test
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iptables,table=filter,chain=INPUT,ruleid=ssh pkts=100i,bytes=1024i 1453831884664956455
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iptables,table=filter,chain=INPUT,ruleid=httpd pkts=42i,bytes=2048i 1453831884664956455
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```
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