85 lines
3.1 KiB
Markdown
85 lines
3.1 KiB
Markdown
# Iptables Plugin
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The iptables plugin gathers packets and bytes counters for rules within a set of table and chain from the Linux's iptables firewall.
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Rules are identified through associated comment. **Rules without comment are ignored**.
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Indeed we need a unique ID for the rule and the rule number is not a constant: it may vary when rules are inserted/deleted at start-up or by automatic tools (interactive firewalls, fail2ban, ...).
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Also when the rule set is becoming big (hundreds of lines) most people are interested in monitoring 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 are named with a unique comment**. Comments are added using the `-m comment --comment "my comment"` iptables options.
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The iptables command requires CAP_NET_ADMIN and CAP_NET_RAW capabilities. You 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 the simplest and recommended option.
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* Configure sudo to grant telegraf to run iptables. This is the most 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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```
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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 required to transmit the capabilities bounding set to the forked process.
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### Using sudo
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You may edit your sudo configuration with the following:
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```sudo
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telegraf ALL=(root) NOPASSWD: /usr/bin/iptables -nvL *
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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 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.
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### Configuration:
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```toml
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# use sudo to run iptables
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use_sudo = false
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# run iptables with the lock option
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use_lock = false
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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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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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```
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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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```
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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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