[nycbug-talk] CIDR Network Subtraction Tool?

Marc Spitzer mspitzer at gmail.com
Tue Jun 16 16:56:31 EDT 2009

Why not just run a white list as well as a black list, if its in both
white wins.  Makes auditing easier as well


On 6/16/09, Tim A. <techneck at goldenpath.org> wrote:
> 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:
> /usr/ports/net/py-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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