Regex Help — bracketed character classes within non capturing groups?

@PeterPan_321

Copy linkTweet thisAlerts:

Apr 17.2017

Quite often I’ll create regex based filters to recognize and dispose of emails, containing origin IP addresses that are from a foreign system I’d never expect mail from. So, for example, if I’m trying to recognize an address within the range of

[CODE]185.220.0.0 – 185.255.255.255[/CODE]

I might compose a string like this…

[CODE]185.(?:22[0-4]|2[3-5][0-9]).[/CODE]

Granted I’m taking some shortcuts there.You couldn’t, for example, have a second octet be “259”. But still, if I get an origin address like “185.246.22.22”, I’d expect that string to be a match. The “185” is matched literally, the “.” is matched by the escaped “.“, and 246 should be matched by the second alternate in the non capturing group. There, the “2” is matched literally, the “4” falls within the range of the [3-5] group, and the “6” falls within the [0-9] group.

Now it “seems” to work, but that is an assumption based on the fact that once I get SPAM from a system, a dozen or more will usually follow. So if I install the filter and that spam source stops, its a good sign.

The trouble is, when I plug in my regex string and test IP string into the corresponding fields at regex101.com, it reports “Your regular expression does not match the subject string.” Am I doing something wrong, or am I not understanding how to use the online regex tester?

Also in #Full-stackDeveloper _↴