Question

I have a textbox and the only input that it should take is either a single ip address or a range in the form of: 10.2.3.4-10

I have this so far:

string txt = "10.13.11.12-100";

        string re1 = "((?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?))(?![\\d])";   // IPv4 IP Address 1
        string re2 = ".*?"; // Non-greedy match on filler
        string re3 = @"\b([0-9]{1,2}|1[0-9]{2}|2[0-4][0-9]|25[0-5])\b";//"([0-255])";   // Integer Number 1

        Regex r = new Regex(re1 + re2 + re3, RegexOptions.IgnoreCase | RegexOptions.Singleline);
        Regex r2 = new Regex(re1, RegexOptions.IgnoreCase | RegexOptions.Singleline);
        Match m = r.Match(txt);
        Match m3 = r2.Match(txt);
        if (m.Success || m3.Success)
        {...}

Only thing is with that, if I have 100.100.11.11-256 it will still return true since it matches m3.Success above as true.

How to fix that?

Answer 1

For the IP Range Regex:

^10.2.3.(?:[4-9]|10)$

For the single IP address: Regular expression to match DNS hostname or IP Address?