Firewall in Ubuntu

The UFW firewall is the default firewall that ships standard with the Ubuntu Linux Distribution. UFW stands for Uncomplicated Firewall.

• To enable the ufw firewall, open a new Terminal window and execute the following command:

  sudo ufw enable

• To disable the ufw firewall, open a new Terminal windows and execute the following command:

  sudo ufw disable

• To view the status of the ufw execute the below command:

  sudo ufw status

  How do I disable the firewall in Ubuntu Linux server edition? How do I turn off the firewall in Ubuntu Linux version 12.04 or 14.04 LTS server?
  
  The latest version of Ubuntu comes with a program called ufw. It is used for managing a Linux firewall and aims to provide an easy to use interface for the user. [donotprint][/donotprint]

  
  

  A Note About ufw

  As I said earlier, the latest version of Ubuntu comes with ufw (now it is the default firewall configuration tool for Ubuntu). It is developed to ease iptables firewall configuration, ufw provides a user friendly way to create an IPv4 or IPv6 host-based firewall.
  

  List ufw firewall rules, enter:

  $ sudo ufw status verbose
  Sample outputs:
  

  Status: active
  Logging: on (low)
  Default: deny (incoming), allow (outgoing), deny (routed)
  New profiles: skip
   
  To                         Action      From
  --                         ------      ----
  71.81.22.14 80/tcp        ALLOW IN    Anywhere
  71.81.22.15 80/tcp        ALLOW IN    Anywhere

  To disable ufw based firewall, enter:

  $ sudo ufw disable4
  
  
  

  List current firewall rules and stop firewall (old method)

  You can type the following command to see if firewall is active or not (open a terminal or ssh session and type the following command):
  $ sudo iptables -L -n
  Sample outputs:
  

  Chain INPUT (policy ACCEPT) target prot opt source destination ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:53 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:53 ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:67 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:67   Chain FORWARD (policy ACCEPT) target prot opt source destination ACCEPT all -- 0.0.0.0/0 192.168.122.0/24 state RELATED,ESTABLISHED ACCEPT all -- 192.168.122.0/24 0.0.0.0/0 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 REJECT all -- 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable REJECT all -- 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable   Chain OUTPUT (policy ACCEPT) target prot opt source destination

  You can save existing firewall rules as follows:
  $ sudo iptables-save > firewall.rules
  Finally, type the following commands to stop firewall and flush all the rules:
  $ sudo iptables -X
$ sudo iptables -t nat -F
$ sudo iptables -t nat -X
$ sudo iptables -t mangle -F
$ sudo iptables -t mangle -X
$ sudo iptables -P INPUT ACCEPT
$ sudo iptables -P FORWARD ACCEPT
$ sudo iptables -P OUTPUT ACCEPT