This is string for nginx.log (for Zimbra Proxy server)
Code:
$PID_pat = '(\d+\/\d+\/\d+\ \d+\:\d+\:\d+) \[info\] \d+\#\d+\: \*(\d+) ';
$IP_pat = $PID_pat . 'client (\d+\.\d+\.\d+\.\d+) connected to .*';
$OK_pat = $PID_pat . 'client logged in, client: \d+\.\d+\.\d+\.\d+\, server: \d+\.\d+\.\d+\.\d+\:\d+';