Regex to extract only IPv4 addresses from text

Question

I've tried to extract only IP addresses from the the given example input, but it extracts some text with it. Here's my code:

$spfreccord="v=spf1 include:amazonses.com include:nl2go.com include:smtproutes.com include:smtpout.com ip4:46.163.100.196 ip4:46.163.100.194 ip4:85.13.135.76 ~all";

 $regexIpAddress = '/ip[4|6]:([\.\/0-9a-z\:]*)/';        
 preg_match($regexIpAddress, $spfreccord, $ip_match);
 var_dump($ip_match);

I'm looking to match only the IPv4 IP address xxx.xxx.xxx.xxx in each column of the table, but it looks like that the $regexIpAddress is not correct.

Can you please help me find the correct regex to extract only the IPv4 IP addresses? Thanks.

yeh it work just fine but one little problem is that i cannot extract cidr class v=spf1 ip4:205.201.128.0/20 ip4:198.2.128.0/18 ?all is it possible to extract the cidr 205.201.128.0/20 — salaheddine Rmaili, Jun 05 '16 at 10:44
Then change it to: `/\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}(?:\/\d{2})?/` — Thamilhan, Jun 05 '16 at 10:56
Hi @Will you answer is working fine but i don't need to extract the text "ip4" with the ips, Hi @Thamilan your answer is working good for me but one problem is that i cannot extract classes cidr like this `198.2.128.0/18` so please if there is something to add to my ipregex to extract also cidr like this example `198.2.128.0/18` thanks all — salaheddine Rmaili, Jun 05 '16 at 11:02
@sala.eddi mine doesn't extract the text, just the IPs. Look at the output in my example. — Will, Jun 05 '16 at 11:10
Hi Will yes but it extract reccord like this ip4:94.176.182.0 i don't need to extract ip4 beside i need to extract cidr classes like this 198.2.128.0/18, Thanks any way that was very helpful from you HI @Thamilan your answer is the good answer for my question bcause it give me classes and unique ips address thanks a lot — salaheddine Rmaili, Jun 05 '16 at 11:27

score 6 · Accepted Answer · answered Jun 05 '16 at 11:34

Use the following regex:

/\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}(?:\/\d{2})?/

So for this:

$spfreccord="v=spf1 include:amazonses.com include:nl2go.com include:smtproutes.com include:smtpout.com ip4:46.163.100.196 ip4:46.163.100.194 ip4:85.13.135.76 cidr class v=spf1 ip4:205.201.128.0/20 ip4:198.2.128.0/18 ~all";

 $regexIpAddress = '/\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}(?:\/\d{2})?/';        
 preg_match_all($regexIpAddress, $spfreccord, $ip_match);
 var_dump($ip_match);

Gives:

array(1) {
  [0]=>
  array(5) {
    [0]=>
    string(14) "46.163.100.196"
    [1]=>
    string(14) "46.163.100.194"
    [2]=>
    string(12) "85.13.135.76"
    [3]=>
    string(16) "205.201.128.0/20"
    [4]=>
    string(14) "198.2.128.0/18"
  }
}

Will · Answer 2 · 2016-06-05T10:52:07.003

You want preg_match_all(), and a slight modification of your regex:

php >  $regexIpAddress = '/ip4:([0-9.]+)/';
php >  preg_match_all($regexIpAddress, $spfreccord, $ip_match);
php >  var_dump($ip_match[1]);
array(3) {
  [0]=>
  string(14) "46.163.100.196"
  [1]=>
  string(14) "46.163.100.194"
  [2]=>
  string(12) "85.13.135.76"
}
php >

You don't need to match against a-z; it's not a valid part of an IP address, 4 or 6. Since you said you only want IPv4, I've excluded any matching of IPv6 addresses.

If you wanted to include IPv6 as well, you can do this:

php > $regexIpAddress = '/ip[46]:([0-9a-f.:]+)/';
php > preg_match_all($regexIpAddress, $spfreccord, $ip_match);
php > var_dump($ip_match[1]);
array(4) {
  [0]=>
  string(14) "46.163.100.196"
  [1]=>
  string(14) "46.163.100.194"
  [2]=>
  string(12) "85.13.135.76"
  [3]=>
  string(39) "2001:0db8:85a3:0000:0000:8a2e:0370:7334"
}

Regex to extract only IPv4 addresses from text

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