Um, if I'm clear, you need to know how to match a number from 1-126 or from 17-31:

# tests for a 3 digit number from 1 - 126
$num =~ m/^(1(?:[01]\d|2[0-6])|\d?\d)$/; 

# tests for a 2 digit number from 17 - 31
$num =~ m/^(1[7-9]|2\d|3[01])$/;
[download]

This is a bit messy so you may want to investigate methods by which you can check IP's that don't use a regex. Perhaps one of the Net modules.

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Amel
This is my cool %SIG