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A regular expression for IP numbers and ranges

Question:

I need a regular expression for IP ranges such as:
192.168.0.0/16
123.45.67.89

I want to use it in JavaScript to validate user input. Do you have some code?

Answer:

Yes, use the code shown below.

var IP_Validator_Regexp='(1\d{0,2}|2(?:[0-4]\d{0,1}|[6789]|5[0-5]?)?|' + 
 '[3-9]\d?|0)\.(1\d{0,2}|2(?:[0-4]\d{0,1}|[6789]|5[0-5]?)?|[3-9]\d?|0)' +
 '\.(1\d{0,2}|2(?:[0-4]\d{0,1}|[6789]|5[0-5]?)?|[3-9]\d?|0)\.(1\d{0,2}' + 
 '|2(?:[0-4]\d{0,1}|[6789]|5[0-5]?)?|[3-9]\d?|0)(\/(?:[012]\d?|3[012]?' +
 ')){0,1}$';
 
   // how to use it in Javascript
 
   var regex =/IP_Validator_Regexp/;
   if (!(regex.test(document.getElementById('user_ip').value))) {
     alert('This is not a valid IP number');
     return;
   }
 

Generated 0:01:58 on Apr 25, 2018