How to block IP addresses through ufw

The article describes how to block specific IP addresses through ufw.

UFW (Uncomplicated Firewall) is a standard iptables firewall utility for Ubuntu Linux. It uses a command line interface consisting of a small number of simple commands. UFW is a convenient way to create a basic IPv4 or IPv6 firewall to protect the server.

Block specific IP addresses through ufw

Syntax:

sudo ufw deny from {ip-address-here} to any

To block or close all packets with 192.168.1.5, enter:

sudo ufw deny from 192.168.1.5 to any

We show the status of the firewall including the rules. To check recently added rules, enter:

$ sudo ufw status numbered

or

$ sudo ufw status

Block specific IP and port numbers through ufw

Syntax:

ufw deny from {ip-address-here} to any port {port-number-here}

To block or close the "spam" IP addresses 202.54.1.5 of port 80, enter:

sudo ufw deny from 202.54.1.5 to any port 80

We check again using the following command:

$ sudo ufw status numbered

Result:

Closing certain IP, port and protocol numbers through ufw

Syntax:

sudo ufw deny proto {tcp|udp} from {ip-address-here} to any port {port-number-here}

For example, blocking malicious IP addresses 202.54.1.1 tcp port 22, enter:

$ sudo ufw deny proto tcp from 202.54.1.1 to any port 22
$ sudo ufw status numbered

Subnet lock via ufw. The syntax is the same:

$ sudo ufw deny proto tcp from sub/net to any port 22
$ sudo ufw deny proto tcp from 202.54.1.0/24 to any port 22

How to remove blocking and unlock IP addresses

Syntax:

$ sudo ufw status numbered
$ sudo ufw delete NUM

To remove rule # 4, enter:

$ sudo ufw delete 4

Result:

 deny from 202.54.1.5 to any port 80
Proceed with operation (y|n)? y
Rule deleted

Hint: UFW NOT blocking the IP address

In order to avoid unnecessary problems with unnecessary blocking, you need to change the / etc / ufw / before.rules file and add the section “Block an IP Address” after “# End required lines”.

$ sudo vi /etc/ufw/before.rules

# End required lines

Add your rule for block against spam or hackers:



Save and close the file. And - reload the firewall:

$ sudo ufw reload