[nycbug-talk] CIDR Network Subtraction Tool?

Tim A. techneck at goldenpath.org
Tue Jun 16 16:44:47 EDT 2009

Tim A. wrote:
> Scenario:
> spamd blacklisting from foreign.txt source file with a list of all 
> non-US IP space.
> Problem:
> Occasionally we spark up a new non-US vendor relationship and need to 
> receive email from their email servers but their IP addresses have 
> been blacklisted in foreign.txt
> Solution:
> Subtract their IPs / ISPs netblock from the /8 entry.
> Currently, I do this by hand. Googling for network calculators spits 
> back a ton of tools that calculate subnets but none of which do this 
> sort of network subtraction.
> If anyone is aware of such a tool, please share.

Found a python tool called netaddr:

Just FYI, in case it helps anyone else out there.

I was thinking more of a nifty multi-platform (and windows too) GUI 
tool, but this gets the job done, amen.

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