In a combination with a watch command an iptables can be used to monitor a network traffic in a real-time.
This is especially useful for troubleshooting various network issues.
Bellow you will find some examples of how to monitor the network traffic in a real-time using the iptables and watch commands.
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Monitor Traffic in Real-Time using IPTables
To monitor the network traffic using the iptables, execute it in a combination with the watch command:
$ watch -n0 "sudo iptables -v -L"
You can reduce an output by selected a specific firewall chain to monitor:
$ watch -n0 "sudo iptables -v -L <chainName>"
- example-
$ watch -n0 "sudo iptables -v -L OUTPUT"
To narrow down the output to a particular iptables rule, execute
$ watch -n0 "sudo iptables -v -L <chainName> <ruleNumber>"
- example-
$ watch -n0 "sudo iptables -v -L OUTPUT 5"
To list the iptables rules with line numbers, add the --line-number option.
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