Comments on: Ip address validation in PHP using regular expression

By: shruti joshi

shruti joshi — Mon, 16 Apr 2012 02:12:52 +0000

Thank you for giving code of IP validation.

By: Mihai Voiculescu

Mihai Voiculescu — Sun, 06 Feb 2011 14:14:23 +0000

Thanks for this code. It is very useful.

By: Michael Pedzotti

Michael Pedzotti — Sat, 29 May 2010 15:20:09 +0000

Thanks for the code sample. It helps me to understand the preg_match command a little bit more.

By: Tim

Tim — Thu, 18 Feb 2010 10:32:11 +0000

All of these are rather complex and unless you want a very specific error message why not just use…

function checkIP($ip)
{
$cIP = ip2long($ip);
$fIP = long2ip($cIP);
return $fIP;
}

It will return 0.0.0.0 if an invalid IP or string is passed to it.

By: john

john — Fri, 18 Dec 2009 11:17:35 +0000

Sorry don’t know why but the code is not pasting correctly try again…..//

function check_ip_address($ip_address) {
$octets = explode(‘.’,$ip_address);
if (($octets[0] > 0 && $octets[0] 0 && $octets[1] 0 && $octets[2] 0 && $octets[3] < 255) && (count($octets) == 4))
{ return TRUE; }
}

By: john

john — Fri, 18 Dec 2009 11:13:17 +0000

If you are checking for a valid IP address the first octet should be less than 224 – above this are reserved for multicast addresses. You may also want to check for broadcast addresses but this woupld require a lot more testing based on the Class of IP address. You may also want to check for RFC 1918 private addresses and well as 127.x.x.x looopback. I do not think regular expressions are they way to do this and it will require a proper php function. Here is my basic function just checking for a valid unicast IP address….

function check_ip_address($ip_address) {

$octets = explode(‘.’,$ip_address);

if (($octets[0] > 0 && $octets[0] 0 && $octets[1] 0 && $octets[2] 0 && $octets[3] < 255) &&
(count($octets) == 4))

{ return TRUE; }

}

By: Juanra

Juanra — Wed, 19 Aug 2009 17:44:23 +0000

Another way to do this:

function validateIpAddress($ip_addr) {
$long = ip2long($ip_addr);
return !($long == -1 || $long === FALSE);
}

By: Roshan

Roshan — Fri, 08 Aug 2008 15:57:28 +0000

Hi Decon…thanks for sharing that link…

By: Decon

Decon — Fri, 08 Aug 2008 13:18:13 +0000

You might find this URL useful (and faster without using reg-ex)

http://www.jimgrill.com/pages/content/validateip

By: Brian Szymanski

Brian Szymanski — Wed, 25 Jun 2008 17:27:09 +0000

Or you could do the whole kit+kaboodle in one regexp like so: return preg_match("/^((\d{1,2}|[01]\d{2}|2([0-4]\d|5[0-5]))\.){3}(\d{1,2}|[01]\d{2}|2([0-4]\d|5[0-5]))$/",$ip_addr))

By: Roshan

Roshan — Fri, 25 Apr 2008 15:47:39 +0000

It won’t work…try it…it will just validate a number like 0,1,2 or 5 only since it is equivalent to character set [0125]

By: CC

CC — Fri, 25 Apr 2008 13:51:42 +0000

can you not simply use a regexp of: -

^[0-255]\.[0-255]\.[0-255]\.[0-255]$

i.e. four integers in the range of 0 to 255 with a period separating them?