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<tt>Scenario:<br>
spamd blacklisting from foreign.txt source file with a list of all
non-US IP space.<br>
Problem:<br>
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<br>
Solution:<br>
Subtract their IPs / ISPs netblock from the /8 entry.<br>
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.<br>
If anyone is aware of such a tool, please share.<br>
<br>
Example:<br>
89 . 0 . 0 . 0 /8<br>
- 89 .208 .106 . 0 /24<br>
-------------------------------<br>
<br>
</tt>
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<tr style="height: 12.75pt;" height="17">
<td style="height: 12.75pt;" height="17">89.0.0.0/9</td>
</tr>
<tr style="height: 12.75pt;" height="17">
<td style="height: 12.75pt;" height="17">89.128.0.0/10</td>
</tr>
<tr style="height: 12.75pt;" height="17">
<td style="height: 12.75pt;" height="17">89.192.0.0/12</td>
</tr>
<tr style="height: 12.75pt;" height="17">
<td style="height: 12.75pt;" height="17">89.208.0.0/18</td>
</tr>
<tr style="height: 12.75pt;" height="17">
<td style="height: 12.75pt;" height="17">89.208.128.0/18</td>
</tr>
<tr style="height: 12.75pt;" height="17">
<td style="height: 12.75pt;" height="17">89.208.192.0/18</td>
</tr>
<tr style="height: 12.75pt;" height="17">
<td style="height: 12.75pt;" height="17">89.208.64.0/19</td>
</tr>
<tr style="height: 12.75pt;" height="17">
<td style="height: 12.75pt;" height="17">89.208.96.0/21</td>
</tr>
<tr style="height: 12.75pt;" height="17">
<td style="height: 12.75pt;" height="17">89.208.104.0/24</td>
</tr>
<tr style="height: 12.75pt;" height="17">
<td style="height: 12.75pt;" height="17">89.208.105.0/24</td>
</tr>
<tr style="height: 12.75pt;" height="17">
<td style="height: 12.75pt;" height="17">89.208.107.0/24</td>
</tr>
<tr style="height: 12.75pt;" height="17">
<td style="height: 12.75pt;" height="17">89.208.108.0/24</td>
</tr>
<tr style="height: 12.75pt;" height="17">
<td style="height: 12.75pt;" height="17">89.208.109.0/24</td>
</tr>
<tr style="height: 12.75pt;" height="17">
<td style="height: 12.75pt;" height="17">89.208.110.0/24</td>
</tr>
<tr style="height: 12.75pt;" height="17">
<td style="height: 12.75pt;" height="17">89.208.111.0/24</td>
</tr>
<tr style="height: 12.75pt;" height="17">
<td style="height: 12.75pt;" height="17">89.208.112.0/20</td>
</tr>
<tr style="height: 12.75pt;" height="17">
<td style="height: 12.75pt;" height="17">89.224.0.0/11</td>
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