UbuntuLinux uses ufw or iptables to configure the firewall

The firewall only supports ssh (port 22) and http (port 80 ). ubuntuLinux can do this using ufw: sudoufwenable & amp; \ sudoufwdefadendeny & amp; \ sudoufwallow22/tcp & amp; \ sudoufwallow80/tcp & amp; &

The firewall only supports ssh (port 22) and http (port 80 ).

In Ubuntu Linux, ufw can be used as follows:
Sudo ufw enable &&\
Sudo ufw default deny &&\
Sudo ufw allow 22/tcp &&\
Sudo ufw allow 80/tcp &&\
Sudo ufw status
You can delete it like this, for example, port 80:
Sudo ufw delete allow 80/tcp

Ubuntu ufw firewall rules order problem see http://www.linuxidc.com/Linux/2015-11/125110.htm

Ubuntu uses iptables to do this:
Sudo ufw disable & sudo ufw default allow sets INPUT/FORWARD/OUTPUT to ACCEPT. If it is DENY, the next step will interrupt all network access to the system, including ssh.
Sudo iptables-F & sudo iptables-X & sudo iptables-Z & sudo iptables-L
Sudo iptables-a input-m state -- state ESTABLISHED, RELATED-j ACCEPT
Sudo iptables-a input-I lo-j ACCEPT
Sudo iptables-a input-p tcp-I eth0 -- dport 22-j ACCEPT
Sudo iptables-a input-p tcp-I eth0 -- dport 80-j ACCEPT
Sudo iptables-a input-j DROP
Iptables-save>/etc/iptables. up. rules switch to the root user for execution. sudo will prompt that you do not have the permission. RedHat's save operation is service iptables save.
Add a line to the end of sudo nano/etc/network/interfaces and apply the firewall rules when the network starts:
Pre-up iptables-restore </etc/iptables. up. rules
View the configured rules:
Sudo iptables-nvL -- line-numbers
Insert a rule to 6th of the INPUT chain:
Sudo iptables-I INPUT 6-j DROP
Modify the 6th rules of the INPUT chain:
Sudo iptables-r input 6-j ACCEPT
Delete 6th rules of the INPUT chain:
Sudo iptables-d input 6

For more iptables tutorials, see the following content::

CentOS 7.0 disable default firewall enable iptables firewall http://www.linuxidc.com/Linux/2015-05/117473.htm

Iptables usage example detailed http://www.linuxidc.com/Linux/2014-03/99159.htm

Linux Firewall iptables detailed tutorial http://www.linuxidc.com/Linux/2013-07/87045.htm

Basic use http://www.linuxidc.com/Linux/2013-08/88535.htm for iptables backup, recovery, and firewall scripts

Linux Firewall iptables detailed explanation of usage rules http://www.linuxidc.com/Linux/2012-08/67952.htm

Linux iptables firewall settings http://www.linuxidc.com/Linux/2015-10/123843.htm

This article permanently updates the link address: Http://www.linuxidc.com/Linux/2016-02/128478.htm