Question

I need a regex pattern that validates IP addresses. This is easy enough to google for, but I there is a small catch. I need the last numbers to be able to accept a range. So the following input would validate.

XXX.XXX.XXX.X-Y

so something like 168.68.2.1-34

I have found patterns for normal IP addresses, but none for handling ranges.

Answer 1

To accept a number between 0 and 255, I’d use (25[0-5]|2[0-4]\d|[0-1]?\d{1,2}). Calling the above expression A, a Regex for an IP Range would look like

A\.A\.A\.A-A

or

(A\.){3}A-A

If the range is optional, use (-A)? instead of -A.

This does not check if the start of the range is smaller than the end, but this cannot be done in Regex with reasonable effort.