Python: ---------- >>> def validate_ip(ip): ... ans = re.search(r'^([1-9]|[1-9]\d|1\d{2}|2[0-4]\d|25[0-5])\.(\d|[1-9]\d|1\d{2}|2[0-4]\d|25[0-5])\.(\d|[1-9]\d|1\d{2}|2[0-4]\d|25[0-5])\.(\d|[1-9]\d|1\d{2}|2[0-4]\d|25[0-5])', ip) ... if ans: ... return True ... else: ... return False ... >>> validate_ip('192.168.0.1') True >>> validate_ip('256.168.0.1') False >>> validate_ip('0.0.0.0') False >>> validate_ip('1.1.1.1') True >>> Perl: ------ $ cat validate_ip.pl sub validate_ip { my $ip = shift; if ($ip =~ /^([1-9]|[1-9]\d|1\d{2}|2[0-4]\d|25[0-5])\.(\d|[1-9]\d|1\d{2}|2[0-4]\d|25[0-5])\.(\d|[1-9]\d|1\d{2}|2[0-4]\d|25[0-5])\.(\d|[1-9]\d|1\d{2}|2[0-4]\d|25[0-5])/) { print("\n$ip is a valid IP Address\n"); return 1; } else { print("\n$ip is NOT a valid IP Address\n"); return 0; } } validate_ip("192.168.0.1"); validate_ip("256.168.0.1"); validate_ip("0.0.0.0"); validate_ip("1.1.1.1"); $ perl validate_ip.pl 192.168.0.1 is a valid IP Address 256.168.0.1 is NOT a valid IP Address 0.0.0.0 is NOT a valid IP Address 1.1.1.1 is a valid IP Address $