iptables counts packets and bytes of all network traffic that passes through it.
To list the packet and byte counters, execute the iptables -L command with the -v option.
By default, the iptables counters are reset after a system reboot, but you can also reset them manually using the -Z option and this note shows some examples how to do this. (more…)
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. (more…)
If you can’t access some service on a remote Linux machine with enabled iptables, this may be caused by the firewall rules.
To troubleshoot connectivity issues, you can temporary disable iptables to see if it is causing them, and then re-enable it.
This short note shows how to temporary disable iptables on Linux (Ubuntu, Debian, CentOS, etc.) for maintenance or troubleshooting, and then re-enable it. (more…)
The iptables is a built in firewall in the most Linux distributions, including CentOS.
Sometimes it is required to stop the iptables for troubleshooting of the network related problems.
Also, if there are some troubles with the recently installed application – you may see on the related forums a suggestion to stop the firewall temporary in order to check if the application works fine without it.
From this article you’ll learn how to check the current status of the iptables firewall, and how to disable or enable it in CentOS. (more…)