Question 1

What is a firewall rule?

Accepted Answer

A firewall rule is a set of criteria that determines whether network traffic should be allowed or blocked. Rules typically specify the protocol (TCP/UDP), direction (inbound or outbound), source IP, destination port, and action (allow or deny).

Question 2

What is the difference between DENY and DROP?

Accepted Answer

DENY (or REJECT in iptables) sends an error response back to the sender, informing them the connection was refused. DROP silently discards the packet with no response, making it appear as if the host does not exist. DROP is generally preferred to avoid leaking information about your firewall configuration.

Question 3

How do I apply iptables rules?

Accepted Answer

Copy the generated commands and run them with sudo in your Linux terminal. Note that iptables rules are not persistent by default — to save them across reboots install iptables-persistent and run sudo netfilter-persistent save.

Question 4

How do I apply UFW rules?

Accepted Answer

Copy the generated ufw commands and run them with sudo. Make sure UFW is enabled first with sudo ufw enable. UFW rules persist across reboots automatically. You can view active rules with sudo ufw status verbose.

Question 5

How do I run the Windows Firewall PowerShell script?

Accepted Answer

Open PowerShell as Administrator, paste the generated New-NetFirewallRule commands, and press Enter. Rules created this way are persistent and visible in Windows Defender Firewall with Advanced Security.

Firewall Rule Generator

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