“IPv4 address” is one of the patterns that you can select on the Match panel. Use it to make a field match a internet address such as 192.168.0.1.
The documentation for Google Analytics explains how you can use a regular expression in Google Analytics to filter on IP addresses. We’ll follow the same example here, but explain how to generate the regular expression with RegexMagic.
10.1.1.1 10.255.255.254 172.0.0.1 172.16.0.1 172.31.255.254 172.255.255.254 192.168.1.1 192.168.255.254 63.212.171.1 63.212.171.254 8.8.8.8 8.8.4.4
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^63\.212\.171\.(25[0-4]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]?)$
Required options: ^$ don’t match at line breaks; dot matches line breaks.
Unused options: Case sensitive.
10.1.1.1 10.255.255.254 172.0.0.1 172.16.0.1 172.31.255.254 172.255.255.254 192.168.1.1 192.168.255.254 63.212.171.1 63.212.171.254 8.8.8.8 8.8.4.4
The regex engine used by Google Analytics does not support regular expressions longer than 255 characters. The POSIX ERE specification allows this limitation but does not require it. RegexMagic always tries to generate regular expressions that are as short and simple as possible. But it will allow the regular expression to be as long as it needs to be to make it do what you specified. If the resulting regex is too long, RegexMagic does provide several options to make it shorter if you allow a change in specifications.
To keep your regex short, turn off the option “validate 0..255 in dotted addresses” and specify ranges that span the whole 0..255 range as much as possible. So specify 63.212.171.0..63.212.171.255 or 63.212.171.1/24 instead of 63.212.171.1..63.212.171.254. When you do this, RegexMagic generates [0-9]{1,3} rather than (25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9]) to match a number between 0 and 255. Though [0-9]{1,3} could match numbers such as 000 or 999 that don’t belong in IPv4 addresses, this isn’t a problem when filtering web logs. The logs don’t contain invalid IP addresses. There’s no need to make the regex longer in order to exclude them. The regex from our example then becomes:
^63\.212\.171\.[0-9]{1,3}$
Required options: ^$ don’t match at line breaks; dot matches line breaks.
Unused options: Case sensitive.
The RegexMagic pattern for IPv4 addresses allows you to specify as many IP ranges as you want delimited with semicolon. RegexMagic will roll all the ranges into one big regex. You can match any private IPv4 address by setting the range to 10.0.0.0/8;172.16.0.0/12;192.168.0.0/16. RegexMagic combines these 3 ranges into one compact regex that still strictly matches all 3:
^(10\.[0-9]{1,3}|172\.(3[01]|2[0-9]|1[6-9])|192\.168)\.[0-9]{1,3}\.[0-9]{1,3}$
Required options: ^$ don’t match at line breaks; dot matches line breaks.
Unused options: Case sensitive.
While Google Analytics can only handle regular expressions up to 255 characters, it does allow you to use multiple filters, all with their own regular expression. So if you want to filter on multiple IP address ranges and the regex RegexMagic generates for all those ranges is too long, have RegexMagic generate one regex for each range, and use those regexes in separate filters in Google Analytics.
Setting the “field validation mode” to “strict” as this example does is appropriate when a regular expression is all you can use to restrict the range of IP addresses. But in other situations, such as when developing your own software, you may be better off with a simpler regex that just matches any combination of 4 numbers with dots between them, and filter the IP addresses in procedural code. If you’ll be processing the matched addresses in procedural code anyway, you’ll likely get better performance from a simple regex with a few extra checks in procedural code.
If you set the “field validation mode” to “average”, RegexMagic will generate a regular expression that is much shorter. The regex still requires a match in the form of 1.2.3.4. But if you set the pattern to restrict the address to certain ranges, the regex may match some addresses beyond the ranges you specified. For example, using “average” field validation with the range set to 10.0.0.0/8;172.16.0.0/12;192.168.0.0/16, the resulting regex will match any IPv4 address that begins with 10, 172, or 192. That includes some addresses that aren’t private IPv4 addresses. But you can see that the “average” regex is simpler than the previous “strict” regex:
^(10|172|192)\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$
Required options: ^$ don’t match at line breaks; dot matches line breaks.
Unused options: Case sensitive.
The more complex your combination of IP ranges, the bigger the difference between “average” and “strict” modes. If “average” isn’t simple enough, “loose” mode grabs any IPv4 address, as if both “limit the IPv4 addresses to these ranges” and “validate 0..255 in dotted addresses” were turned off:
^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$
Required options: ^$ don’t match at line breaks; dot matches line breaks.
Unused options: Case sensitive.