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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 in ubuntu

 

• • ★ 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. This will enable firewall and now you can open or block any port in ubuntu.

 

 

How To Open a TCP port in Ubuntu?

 

• • ★ 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

 

How To Deny/Block port access in Ubuntu?

• • ★ 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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