You can block an entire IP range using CIDR (Classless Inter-Domain Routing) notation with ufw. To block all addresses under 57.141.2.x, you'd specify the network as 57.141.2.0/24.¹

Here is the command:

sudo ufw deny from 57.141.2.0/24

## 💡 How it Works

The /24 is CIDR notation that defines the size of the network block. Think of an IP address as being made of four 8-bit blocks, totaling 32 bits.

• /24 means the first 24 bits (57.141.2) are fixed.

• The remaining 8 bits (32 - 24 = 8) can be any value.

• This effectively blocks the entire range from 57.141.2.0 to 57.141.2.255.

You can also block larger or smaller ranges:

• Block a larger range (e.g., 57.141.0.0 to 57.141.255.255):

  Bash

   

  sudo ufw deny from 57.141.0.0/16
  

• Block a specific port from that range:

  Bash

   

  sudo ufw deny from 57.141.2.0/24 to any port 443
  

## 🛡️ Managing Your Rules

After adding a rule, it's a good idea to check your firewall status.

• Check the status and see rule numbers:

  Bash

   

  sudo ufw status numbered
  

• Delete a rule by its number (if you make a mistake):

  Bash

   

  # Replace '5' with the actual rule number from the command above
  sudo ufw delete 5