Archive for the ‘Networking’ Category

Mounting an NFS Share on OS X: There was a Problem Connecting to the Server

You’ve tried to mount your linux NFS share via the Go menu’s Connect to Server dialogue but you keep getting an error message stating:

There was a problem connecting to the server

There was a problem connecting to the server

You know your URI is formatted correctly (nfs://server/share) and you can mount the share on other Linux hosts so what gives?

It turns out that in order to get OS X to play ball we have to add insecure to the export options of the shares you would like to mount. For example:


Crossfire Ping Monitoring Part 3: The Presentation

In part one of this series we set up a ping monitoring script on each of our servers. In part two we covered importing the data to a centralized database.
The number of potential different uses for this information is making my head spin, but in this installment we will focus on spitting it out out in a way which we can gain some basic insights.


$sql_host = '';
$sql_user = '';
$sql_pass = '';
$sql_base = '';

$sql_h = mysql_pconnect($sql_host, $sql_user, $sql_pass);
$sql_d = mysql_select_db($sql_base, $sql_h);

$now = empty($_GET['time']) ? time() : mysql_real_escape_string($_GET['time']);
$intervals = 100;
$interval = 300; // 5 minutes
$before = $now - $interval;

<meta http-equiv=\"refresh\" content=\"$interval\">
<title>Crossfire PoC</title>
<style type=\"text/css\">
body{background: white; color: black; margin: 10px; padding: 0px; font-family: Arial, sans; font-size: 9pt;}
td, th{font-family: Arial, sans; font-size: 8pt; white-space: nowrap;}
td{vertical-align: top;}
tr.darkrow{background-color: #dddddd;}
tr.lightrow{background-color: #eeeeee;}
a{text-decoration: none;}
h1{margin: 0px 0px 10px 0px; padding: 0px; border-bottom: 1px solid black;}
h2{margin: 10px 0px 5px 0px; padding: 0px; border-top: 1px solid black;}
<h1>Crossfire Ping Monitoring PoC on <a href=\"\"></a></h1>
This is a proof-of-concept showing how it is possible to use a group of hosts which constantly ping-monitor each other to visualize connectivity problems and general downtime.<br>
Each column is a different host. Each row is a slice of 5 minutes. Each cell contains how that host was seen by every other host in the pool during that time.<br>
The monitoring script pings each host 4 times every 5 minutes. If a host does not respond at all it will show up in <span style=\"color: red; font-weight: bolder;\">red</span>. If a host
responds to one or more pings it will show up in black. An empty cell means no host reported any problems.
<a href=\"?time=".($now - ($interval * $intervals))."\">< back</a>
<a href=\"?time=".($now + ($interval * $intervals))."\"> forward ></a>
<tr class=\"darkrow\">

$hosts = array();
$h_result = mysql_query("select * from `hosts` order by `id` desc");
while($h_array = mysql_fetch_array($h_result))
	$hosts["{$h_array['id']}"] = $h_array;



$counter = 0;
while($counter < $intervals)
	$after = $before + $interval;

	if($counter % 2)
		$class = 'dark';
		$class = 'light';

	print("<tr class=\"{$class}row\"><th>".date("Md/y H:i", $before).' - '.date("H:i", $after).'</th>');

	foreach($hosts as $host)
		$log_result = mysql_query("select * from `logs` where `date` > '$before' and `date` < '$after' and `ip` = '{$host['ip']}'");
		while($log_object = mysql_fetch_object($log_result))
			if($log_object->packets == 0){print("<span style=\"color: red; font-weight: bolder;\">");}
			print('• '.$hosts["{$log_object->host}"]['name']." reports {$log_object->packets} replies.");
			if($log_object->packets == 0){print("</span>");}

	$before = $before - $interval;


<a href=\"?time=".($now - ($interval * $intervals))."\">< back</a>
<a href=\"?time=".($now + ($interval * $intervals))."\"> forward ></a>

<h2>So Can You!</h2>
<a href=\"\">Crossfire Ping Monitoring Part 1: The Setup</a><br>
<a href=\"\">Crossfire Ping Monitoring Part 2: Collecting the Data</a><br>
<a href=\"\">Crossfire Ping Monitoring Part 3: The Presentation</a>



Again, we have a very inefficient (in terms of SQL queries) script and I encourage anyone who is interested to improve upon it.

You can see my live PoC at

Crossfire Ping Monitoring Part 2: Collecting the Data

In the previous installment of this series we set up a ping monitoring script on each of our servers set up to ping every other server in the pool. For this example the logs are made available for download via HTTP.

We’re going to re-use the HTTP GET class I posted earlier this week: Portable PHP HTTP(S) GET Request with HTTP Basic Authentication.

Create two tables, one will contain our hosts and one will contain the logs:

CREATE TABLE `hosts` (
  `name` varchar(255) NOT NULL,
  `ip` varchar(64) NOT NULL,
  `location` varchar(255) NOT NULL,
  PRIMARY KEY (`id`)

INSERT INTO `hosts` VALUES (1,'Waveride','',''),(2,'VPS Database','',''),(3,'Iniz','',''),(4,'Prometeus','',''),(5,'domVPS','','');

  `date` int(11) NOT NULL,
  `collected` int(11) NOT NULL,
  `host` int(11) NOT NULL,
  `ip` varchar(64) NOT NULL,
  `packets` int(11) NOT NULL,
  PRIMARY KEY (`id`)

Now we’re going to create a cron script that will fetch the data, parse it, and put it into the database. This is a very inefficient script; I’m sure you can find a better way of running the checks. We’re going to run through the entire log file every time we fetch it so if “headquarters” isn’t able to connect to the VPS for a while we won’t miss any entries. A better way of doing this would be to find the last entry from that host in the logs then skip all of the crossfire.log entries to that point.


$sql_host = '';
$sql_user = '';
$sql_pass = '';
$sql_base = '';

$sql_h = mysql_pconnect($sql_host, $sql_user, $sql_pass);
$sql_d = mysql_select_db($sql_base, $sql_h);

class HTTPRequest
    var $_fp;          // HTTP socket
    var $_url;         // full URL
    var $_host;        // HTTP host
    var $_protocol;    // protocol (HTTP/HTTPS)
    var $_uri;         // request URI
    var $_port;        // port
    var $_user;        // HTTP Basic Auth User
    var $_pass;        // HTTP Basic Auth Password
    // scan url
    function _scan_url()
        $req = $this->_url;
        $pos = strpos($req, '://');
        $this->_protocol = strtolower(substr($req, 0, $pos));
        $req = substr($req, $pos+3);
        $pos = strpos($req, '/');
        if($pos === false)
            $pos = strlen($req);
        $host = substr($req, 0, $pos);
        if(strpos($host, ':') !== false)
            list($this->_host, $this->_port) = explode(':', $host);
            $this->_host = $host;
            $this->_port = ($this->_protocol == 'https') ? 443 : 80;
        $this->_uri = substr($req, $pos);
        if($this->_uri == '')
            $this->_uri = '/';
    // constructor
    function HTTPRequest($url, $user='', $pass='')
        $this->_url = $url;
        $this->_user = $user;
        $this->_pass = $pass;
    // download URL to string
    function DownloadToString()
        $crlf = "\r\n";
        // generate request
        $req = 'GET ' . $this->_uri . ' HTTP/1.0' . $crlf
            .    'Host: ' . $this->_host . $crlf;
                 $req .= "Authorization: Basic " . base64_encode($this->_user . ':' . $this->_pass) . $crlf;
       $req .= $crlf;
        // fetch
        $this->_fp = fsockopen(($this->_protocol == 'https' ? 'ssl://' : '') . $this->_host, $this->_port);
        fwrite($this->_fp, $req);
        while(is_resource($this->_fp) && $this->_fp && !feof($this->_fp))
            $response .= fread($this->_fp, 1024);
        // split header and body
        $pos = strpos($response, $crlf . $crlf);
        if($pos === false)
        $header = substr($response, 0, $pos);
        $body = substr($response, $pos + 2 * strlen($crlf));
        // parse headers
        $headers = array();
        $lines = explode($crlf, $header);
        foreach($lines as $line)
            if(($pos = strpos($line, ':')) !== false)
                $headers[strtolower(trim(substr($line, 0, $pos)))] = trim(substr($line, $pos+1));
        // redirection?
            $http = new HTTPRequest($headers['location']);

$h_result = mysql_query("select * from `hosts` order by `id` desc");
while($h_object = mysql_fetch_object($h_result))
	$r = new HTTPRequest($h_object->location);
	$response = trim($r->DownloadToString());

	$lines = explode("\n", $response);
	foreach($lines as $line)
		$line = str_replace('  ', ' ', $line);
		$e = explode(' ', $line);
		$date = strtotime($e[0].' '.$e[1].' '.$e[2].' '.$e[3].' '.$e[4].' '.$e[5]);
		$ip = mysql_real_escape_string($e[6]);
		$packets = (int) $e[9];
		$check_result = mysql_query("select * from `logs` where `host` = '$h_object->id' and `date` = '$date' and `ip` = '$ip'");
		if(mysql_num_rows($check_result) == 0)
			mysql_query("insert into `logs` (`date`, `collected`, `host`, `ip`, `packets`) values ('$date', '".time()."', '{$h_object->id}', '$ip', '$packets')");


Drop this into your crontab to make it collect every so often, I’m going with 5 minutes here but it doesn’t matter if you only collect the logs daily.

*/5 * * * * apache /usr/bin/php /path/to/import.php
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