PHP - Detect location by IP - Here is an useful code snippet to detect the location of a specific IP. The function below takes one IP as a parameter, and returns the location of the IP. If no location is found, UNKNOWN is returned. - Source: http://snipplr.com/view/48386/detect-location-by-ip-city-state/

function.php

<?php
function detect_city($ip) {
        
    $default = 'UNKNOWN';

    if (!is_string($ip) || strlen($ip) < 1 || $ip == '127.0.0.1' || $ip == 'localhost')
        $ip = '8.8.8.8';

    $curlopt_useragent = 'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2) Gecko/20100115 Firefox/3.6 (.NET CLR 3.5.30729)';
    
    $url = 'http://ipinfodb.com/ip_locator.php?ip=' . urlencode($ip);
    $ch = curl_init();
    
    $curl_opt = array(
        CURLOPT_FOLLOWLOCATION  => 1,
        CURLOPT_HEADER      => 0,
        CURLOPT_RETURNTRANSFER  => 1,
        CURLOPT_USERAGENT   => $curlopt_useragent,
        CURLOPT_URL       => $url,
        CURLOPT_TIMEOUT         => 1,
        CURLOPT_REFERER         => 'http://' . $_SERVER['HTTP_HOST'],
    );
    
    curl_setopt_array($ch, $curl_opt);
    
    $content = curl_exec($ch);
    
    if (!is_null($curl_info)) {
        $curl_info = curl_getinfo($ch);
    }
    
    curl_close($ch);
    
    if ( preg_match('{<li>City : ([^<]*)</li>}i', $content, $regs) )  {
        $city = $regs[1];
    }
    if ( preg_match('{<li>State/Province : ([^<]*)</li>}i', $content, $regs) )  {
        $state = $regs[1];
    }

    if( $city!='' && $state!='' ){
      $location = $city . ', ' . $state;
      return $location;
    }else{
      return $default; 
    }
    
}