问下大家，这个正则该如何去写呢？

\b(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b

\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b

$links = [
    'rtsp://admin:admin123@192.168.140.142:554/h264/cam/realmonitor?channel=1&subtype=0',
    'rtsp://admin:admin123@192.168.140.125/h264/cam/realmonitor?channel=1&subtype=0'
];

$ip = [];
foreach ($links as $link) {
    preg_match('/\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}/', $link, $ip);
    echo $ip[0] . PHP_EOL;
}

// 输出
// 192.168.140.142
// 192.168.140.125

上个图自己看吧

'rtsp://admin:admin123@192.168.140.142:554/h264/cam/realmonitor?channel=1&subtype=0'.replace(/.*?(\d+\.\d+\.\d+\.\d+).*/,"$1")