How do I deny connections with an IP range?

[mariusmbp]

Hello guys

I would like to know how do I deny incoming and outgoing connections with an IP range? (for example 1.1.1.1 - 1.1.1.255)

I want to perform this task directly into the OS without using any third party software like Little Snitch or DNS or router filtering.

 

[DeltaMac]

Why would you not use a good tool like Little Snitch?

What do you do if an app that you work with decides to use an IP from a different range, or a port that you don't normally use suddenly opens? (Little Snitch will easily answer that question for you )

Within the OS X system, it will help if you could learn how to use pf.
Here's a short intro article about that.