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I have a list of ranges for IP addresses that I want to block, the ranges are like 210.80.32.0 to 210.80.63.255

How can I dynamically determine the right 210.80.32.0/NUMBER to capture the full range? 

sudo ufw deny 210.80.32.0/???

I am reading these IP ranges in once a month from text files to add to my firewall rules, I tear the firewall down once a month and rebuild it to capture any changes in these ranges. Currently I am just doing lowerrange/20 in the rule.

So I need to get the two network values by splitting the string on . then do the math to determine how many there are.. and add a rule for each network?

JoGotta
  • 13

1 Answers1

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You are using CDIR notation here. You may want to read more about CDIR notation and subnet masks.

In your example, you could break out the two networks into:

  1. 210.80.32.0/24
  2. 210.80.33.0/24

This translates to:

  • 255.255.255.0

or:

  1. 210.80.32.0-254
  2. 210.80.33.0-254

You should now be able to perform:

sudo ufw deny 210.80.32.0/24 && sudo ufw deny 210.80.33.0/24

Other examples

You could block 210.80.0.0/16, which would block 210.80.0-254.0.254, but this will block IPs in ranges not specified in the original post.

earthmeLon
  • 11,658