Ubuntu default Firewall UFW Settings
Ubuntu Default Firewall UFW Settings
1. installation
sudo apt-get install ufw
2. enabled
sudo ufw enable
sudo ufw default deny
After running the above two commands, the firewall is turned on and automatically turned on when the system starts. Turn off all external access to this machine, but local access to external is normal.
3. On/Off
sudo ufw allow|deny [service]
Open or close a port, for example:
sudo ufw allow smtp Allow all external IPs to access port 25/tcp (smtp) on this machine
sudo ufw allow port 22/tcp Allow all external IPs to access port 22/tcp (ssh)
sudo ufw allow 53 Allow external access to port 53 (tcp/udp)
sudo ufw allow from 192.168.1.100 Allow this IP access to all native ports
sudo ufw allow proto udp 192.168.0.1 port 53 to 192.168.0.2 port 53
sudo ufw deny smtp prohibits external access to smtp services
sudo ufw delete allow smtp Delete a rule created above
4. View firewall status
sudo ufw status
For general users, you only need to set the following settings:
sudo apt-get install ufw
sudo ufw enable
sudo ufw default deny
The above three commands are safe enough. If you need to open some services, use sudo ufw allow.
Turn firewall on/off (default setting is 'disable')
sudo ufw enable|disable
transition log status
sudo ufw logging on|off
Set default policies (e.g."mostly open" vs "mostly closed")
sudo ufw default allow|deny
Permitted or blocked ports (see the list of services in "status"). A service name that exists in/etc/services can be specified as "protocol: port" or via meta-data of the package. The 'allow' argument adds entries to/etc/ufw/maps, whereas 'deny' does the opposite. The basic syntax is as follows:
sudo ufw allow|deny [service]
Displays the listening status of firewalls and ports, see/var/lib/ufw/maps. Numbers in parentheses will not be displayed.
sudo ufw status
Examples of UFW use:
Allow 53 ports
$ sudo ufw allow 53
Disable port 53
$ sudo ufw delete allow 53
Allow 80 ports
$ sudo ufw allow 80/tcp
Disable port 80
$ sudo ufw delete allow 80/tcp
Allow smtp port
$ sudo ufw allow smtp
Remove license for smtp port
$ sudo ufw delete allow smtp
Allow a specific IP
$ sudo ufw allow from 192.168.254.254
Delete the rule above
$ sudo ufw delete allow from 192.168.254.254
