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<?php /** * Check if a given ip is in a network * @param string $ip IP to check in IPV4 format eg. 127.0.0.1 * @param string $range IP/CIDR netmask eg. 127.0.0.0/24, also 127.0.0.1 is accepted and /32 assumed * @return boolean true if the ip is in this range / false if not. */ function ip_in_range( $ip, $range ) { if ( strpos( $range, '/' ) == false ) { $range .= '/32'; } // $range is in IP/CIDR format eg 127.0.0.1/24 list( $range, $netmask ) = explode( '/', $range, 2 ); $range_decimal = ip2long( $range ); $ip_decimal = ip2long( $ip ); $wildcard_decimal = pow( 2, ( 32 - $netmask ) ) - 1; $netmask_decimal = ~ $wildcard_decimal; return ( ( $ip_decimal & $netmask_decimal ) == ( $range_decimal & $netmask_decimal ) ); } var_dump(ip_in_range("204.15.23.255", "204.15.20.0/22"));