You can flush the iptables rules under Ubuntu Linux using the following steps:
- Open a terminal window.
- Run the following command to flush all the iptables rules:
sudo iptables -F
This will remove all of the iptables rules and return the firewall to its default state, allowing all incoming and outgoing traffic.
Alternatively, you can use the following command to remove all iptables chains:
sudo iptables -F
sudo iptables -X
Note that flushing iptables will remove all custom firewall rules that you may have added, so be careful and make sure you understand the potential consequences of flushing iptables.
In some cases, you may need to also flush the NAT table to remove any NAT rules you may have added. You can flush the NAT table using the following command:
sudo iptables -t nat -F