how to validate IP address

Anon

anybody know that how to use Javascript or php coding to validate IP addresses? i want to validate IP address before it can insert into database...just to make sure that format of IP address is correct so that there is no rubbish in database...hope u all can help me......thank you very much

Anon

"Validate" is a pretty vague term - do you just care if it looks right, or do you want to make sure that there actually is a machine visble out there with that particular IP?

if it's just the look of the thing,

if(preg_match('/(\d{1,3}).(\d{1,3}).(\d{1,3}).(\d{1,3})/',$ip,$match)
{
if($match[1]<256 && $match[2]<256 && $match[3]<256)
{
...looks like an IP to me...
}
}

Anon

Have a look at my source code at:

http://www.feralchildren.com/getcountry.html
- there's an IP validation routine in there somewhere. It also checks for private addresses. But note that in spite of what the comment says, it does not check leading zeroes.

Also, I have an idea that the maximum value for the first number is 224 and not 255. Can anyone confirm that, or did I dream it?

Anon

There are a bunch of IPv4 address blocks reserved by IANA for various uses.

000-002, 005, 007, 023, 027, 031, 036, 037, 039, 041, 042, 058-060, 069-079, 085-127, 197, 221-223, 240-255

Details at http://www.iana.org/assignments/ipv4-address-space

Anon

It depends on what you think "validation" entails. Why not go the whole hog and do a whois lookup?

Anon

ok thanks....Grumbler n Andreww Ward... i just want to make sure the format of Ip address is correct...users only can key in the IP address in this format xxx.xxx.xxx.xxx so...i think i'll try all ur suggestion...again...thanks...