How To Open Or Block Port In Ubuntu Linux Firewall

How To Open Or Block Port In Ubuntu Linux Firewall


Linux is the best-known and most-used open-source operating system. As an operating system, Linux is software that sits underneath all of the other software on a computer, receiving requests from those programs and relaying these requests to the computer’s hardware.

A Linux distribution is a selection of coordinated software around the Linux kernel, which in some cases is also a more or less adapted distribution kernel that is usually maintained in close coordination with Upstream itself.

In computing, a firewall is a network security system that monitors and controls the incoming and outgoing network traffic based on predetermined security rules. A firewall typically establishes a barrier between a trusted network and an untrusted network, such as the Internet.

Requirements

    • Root privileges
    • UFW

Check the current status of the firewall

    • Type the following command: sudo ufw status verbose
    • Type Your Password and Press Enter.

    • Output Results will show you UFW Status is Active or Inactive.

    • If Output results are Inactive then you need to activate the UFW. Type the following command: sudo ufw enable.

How To Open a TCP port?

    • To allow incoming TCP Port, Type the following command: sudo ufw allow (port)/tcp
    • For example, To allow incoming TCP packets on port 22, enter: sudo ufw allow 22/tcp

    • Let’s check the configuration, Type the following command: sudo ufw status verbose

    •  

Deny/blocking port access

    • To deny TCP Port, Type the following command: sudo ufw deny (port)/tcp
    • For example, To deny TCP packets on port 22, enter: sudo ufw deny 22/tcp
    • Let’s check the configuration, Type the following command: sudo ufw status verbose


 

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