What regex can I use to match any valid IP-address

Question

What regex can I use to match any valid IP-address represented in dot-decimal notation?

Answer 1

if($ip=~/^(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})$/ &&(($1<=255  && $2<=255 && $3<=255  &&$4<=255 )))
     {
         print "valid\n";
     }
     else
     {
         print "Invalid\n";
     }

Answer 2

IPv4 ip validation with port number

if ( $ip =~ /(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})(:(\d{1,5}))?/ )
{
    if( $1 > 255 || $2 > 255 || $3 > 255 || $4 > 255)
    {
        print "invalid ip\n";
        return ;
    }
    if( ( defined $6) && ( $6 > 65536 ))
    {
        print "invalid port\n";
        return ;
    }
    print "valid ip \n";
}
else
{
    print "invalid ip\n";
    return ;
}

Answer 3

(?:(?:[01]?\d{1,2}|2[0-4]\d|25[0-5])\.){3}(?:[01]?\d{1,2}|2[0-4]\d|25[0-5])

Actually matches some invalid IP addresses, such as:

192.168.00.001

A slightly more refined solution would be:

(?:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)\.){3}(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)$

Answer 4

How do I write a regular expression that matches an IPv4 dotted address?

Long story short: Don't do it ^^.

Answer 5

$ip='123.0.0.1';
if($ip=~/^(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})$/ &&((($1<=255 && $1 > 0) && $2<=255 && $3<=255  &&$4<=255 )))
 {
     print "valid\n";
 }
 else
 {
     print "Invalid\n";
 }

Blockquote

Here in this case we are validating 0.0.0.0 will not be consider the valid IP. and supporting all remaing IP's upto 1.0.0.0 to 255.255.255.255`enter code here

Blockquote

Answer 6

If you can leave a perl module behind - then do it.

what about:

if( $ip=~ m/^(\d\d?\d?)\.(\d\d?\d?)\.(\d\d?\d?)\.(\d\d?\d?)/ && 
          ( $1 <= 255 && $2 <= 255 && $3 <= 255 && $4 <= 255 )
) {    
    print "valid IP.";
}