php[tek] 2017: Atlanta


(PHP 5 >= 5.1.0, PHP 7)

inet_ntopConverts a packed internet address to a human readable representation


string inet_ntop ( string $in_addr )

This function converts a 32bit IPv4, or 128bit IPv6 address (if PHP was built with IPv6 support enabled) into an address family appropriate string representation.



A 32bit IPv4, or 128bit IPv6 address.

Return Values

Returns a string representation of the address or FALSE on failure.


Example #1 inet_ntop() Example

chr(127) . chr(0) . chr(0) . chr(1);
$expanded inet_ntop($packed);

/* Outputs: */
echo $expanded;

$packed str_repeat(chr(0), 15) . chr(1);
$expanded inet_ntop($packed);

/* Outputs: ::1 */
echo $expanded;


Version Description
5.3.0 This function is now available on Windows platforms.

See Also

  • long2ip() - Converts an long integer address into a string in (IPv4) Internet standard dotted format
  • ip2long() - Converts a string containing an (IPv4) Internet Protocol dotted address into a long integer
  • inet_pton() - Converts a human readable IP address to its packed in_addr representation

add a note add a note

User Contributed Notes 4 notes

ryansun81 at gmail dot com
6 years ago
For people who wondering what the meaning of this function name:
pton: a presentation(printable) format address to network address
ntop: a network address to presentation(printable) format address
MagicalTux at FF dot st
11 years ago
For people who need this function but don't have it, I could write a function which should give almost the same result.

function my_inet_ntop($ip) {
    if (
strlen($ip)==4) {
// ipv4
    } elseif(
strlen($ip)==16) {
// ipv6
$ip as $seg) {
$seg{0}=='0') $seg=substr($seg,1);
            if (
$seg!='') {
            } else {
                if (
strpos($res,'::')===false) {
                    if (
substr($res,-1)==':') continue;

I followed IPv6 reprenstation rules :
- A series of "0"s in a 16bit block can by represented by "0".
- A series of blocks containing only "0"s can be suppressed and represented by "::" (this can be done only once)

(source : )

= str_repeat(chr(0), 15) . chr(1);
$expanded = my_inet_ntop($packed);

/* Outputs: ::1 */
echo $expanded;

I checked in CVS (2005-04-25) and didn't find the inet_ntop function (I really needed to handle IPv6) so I implemented it myself !
PandoraBox2007 at gmail dot com
5 years ago
Before inet_pton nice work


no need compare compress data
string inet_ntop ( string $in_addr [, bool $compress = false] )

marcus at synchromedia dot co dot uk
1 year ago
PHP's inet_ntop function is not compatible with the binary representation used by MySQL's INET6_ATON function, assuming you are using the recommended method of storing both IPv4 and IPv6 addresses in a VARBINARY(16) field. You need to convert it like this:

* Convert a MySQL binary v4 (4-byte) or v6 (16-byte) IP address to a printable string.
* @param string $ip A binary string containing an IP address, as returned from MySQL's INET6_ATON function
* @return string Empty if not valid.
function inet6_ntop($ip) {
    $l = strlen($ip);
    if ($l == 4 or $l == 16) {
        return inet_ntop(pack('A' . $l, $ip));
    return '';

You don't need a function going the other way because MySQL's INET6_NTOA is already compatible with PHP's inet_pton function.
To Top