Require help in validating the IpAddress string using Regex

Question

I have string in format:

172.60.136.145,172.60.136.146,172.60.136.147,........

and I need help in validating the IpAddresses in the string using Regex

Answer 1

For specific such as above

172\.60\.136\.[0-9]{1-3}

which nails it specifically to the range of 172.60.136.0 through 999

of course that doesnt cover valid only IPs, that would allow 172.60.136.0 or 172.60.136.999

(0?0?[1-9]|0?[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-4])(\\.(0?0?[0-9]|0?[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-4])){2}(\\.(0?0?[1-9]|0?[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-4]))

Does test that the IP is valid, it allows 1.0.0.1, through 254.254.254.254, wont allow anything ending in .0 etc.

Answer 2

In PHP:

$tmp = explode(',', $ips);
$tmp = array_map('ip2long', $tmp);
if (array_search(false, $tmp, true) !== false) {
    // at least one ip is invalid
}

Answer 3

I'm not sure regex is your best option here as ip addresses are only valid if the numbers are 254 or less

I would split the string at the commas and then split each one of those by a period. I would check that there are 4 sections and that each section can be converted to a number which is 254 or less.

something like this untested pseudo code

string[] addresses = myString.Split(",");
foreach(string address in addresses)
{
    string[] numbers = address.Split(".");
    if (numbers.Length==4)
    {
         Foreach(string number in numbers)
         {
              // need to check that the last number is not a zero as well - not shown here
              int value = Convert.ToInt32(number);
              if (value<0 && value>254)
              {
                  //invalid
              }
         }
    }
    else
    {
        //invalid
    }
}

there are probably classes you could use in your language to help with this but you don't say what language it is. You could do this in c#:

string[] addresses = myString.Split(",");
foreach(string address in addresses)
{
    IpAddress ipAddress;
    if (!IpAddress.TryParse(address, out ipAddress))
    {
        //invalid
    }
}

if you just wanted to invalid ones you could do:

IPAddress ipAddress;
string[] addresses = myString.Split (",");
foreach (string address in addresses.Where (address => !IPAddress.TryParse (address, out ipAddress)))
    {
        //all elements in this loop will be invalid entries
        // remove the '!' to get only the valid ones 
    }

Answer 4

Try with:

/^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/