class NetworkConfig {
    /*
     * Pass the output of ifconfig into the constructor and this class will create a
     * usable data structure to access config info.  To define parsing fields for
     * the various link encapsulation types, modify the $baseFieldMap or
     * $encapFieldMap arrays as needed
     */
    private $interface = array();
 
    private $baseFieldMap  = array(
                            'rx'          => 'RX bytes:',
                            'tx'          => 'TX bytes:'
                            );
 
    private $encapFieldMap = array(
        'Ethernet'       => array(
                            'mac_address' => 'HWaddr ',
                            'ip_address'  => 'inet addr:',
                            'broadcast'   => 'Bcast:',
                            'netmask'     => 'Mask:'),
        'Local Loopback' => array(
                            'ip_address'  => 'inet addr:')
    );
 
    function __construct($config) {
        $interfaces = split("\n\n", $config);
 
        foreach ($interfaces as $if) {
            if (strlen(trim($if)) > 0) {
                $interface = new stdClass;
                $interface->name = substr($if, 0, strpos($if, " "));
 
                //$interface->raw_output = $if; // raw ifconfig output for the interface
                $interface->encapsulation = TextParser::extractBetween($if, "Link encap:", array("\n", "  "));
 
                $extractFields = $this->baseFieldMap;
                if (is_array($this->encapFieldMap[$interface->encapsulation]) && count($this->encapFieldMap[$interface->encapsulation]) > 0) {
                    $extractFields = array_merge($extractFields, $this->encapFieldMap[$interface->encapsulation]);
                }
 
                foreach ($extractFields as $field => $value) {
                    $interface->$field = TextParser::extractBetween($if, $value, array("\n", "  ", '  '));
                }
                $this->__set($interface->name, $interface);
            }
        }
    }
 
    public function __set($name, $value) {
        $this->interface[$name] = $value;
    }
 
    public function __get($name) {
        if (array_key_exists($name, $this->interface)) {
            return $this->interface[$name];
        }
        $trace = debug_backtrace();
        trigger_error('Undefined property via __get(): ' . $name . ' in ' . $trace[0]['file'] . ' on line ' . $trace[0]['line'], E_USER_NOTICE);
        return null;
    }
 
    public function getInterfaceNames() {
        return array_keys($this->interface);
    }
 
    public function getInterfacesByType($type) {
        $return = array();
        $ifs = $this->getInterfaceNames();
        foreach ($ifs as $if) {
            $iface = $this->__get($if);
            if ($iface->encapsulation == $type) {
                $return[] = $iface;
            }
        }
        return $return;
    }
}
 
class TextParser {
    /*
     * $startInclusive - include the startString matched upon in the final output
     * $stopSting - can accept an array, and will match/terminate on the first value found in the string
    */
    public static function extractBetween(&$string, $startString, $stopString, $startInclusive = false) {
        $startAdd = 0;
        if ($startInclusive == false) {
            $startAdd = strlen($startString);
        }
        $startPos = strpos($string, $startString);
        $startPos += $startAdd;
 
        if (is_array($stopString)) {
            $stopCompare = array();
            foreach ($stopString as $ss) {
                $stp = (strpos($string, $ss, $startPos) - $startPos);
                if ($stp > 0) {
                    $stopCompare[] = $stp;
                }
            }
            if (count($stopCompare) == 0) {
                $extractionLength = 0;
            } else {
                $extractionLength = min($stopCompare);
            }
        } else {
            $extractionLength = (strpos($string, $stopString, $startPos) - $startPos);
        }
        //echo '$string: ' . $string . "\n" . '$extractionLength: ' . $extractionLength . "\n";
        //echo '$extractionLength: ' . $extractionLength . "\n";
        if ($extractionLength > 0) {
            $rtn = trim(substr($string, $startPos, $extractionLength));
        } elseif ($extractionLength < 0) {
            $rtn = trim(substr($string, $startPos));
        } else {
            $rtn = '';
        }
        return $rtn;
    }
}
 

Revealing the server type and version number can make it easy to identify servers vulnerable to attacks affecting a given web server version.  By hiding or changing the server signature, a system wont be inherently more secure, but it will make it less visible considering most machines will more easily give up their version numbers.  Perhaps you want to display a message to the users in an auto-indexed sectioned of your website.  You can setup a "readme" file and tell apache to include it as a footer to auto-index pages with the ReadmeName directive.  What if you wanted to hard code a message, or even display a message after a readme file has been included?

Need to modify the Apache source...

First, these directives will disable the display of version numbers & installed modules:

ServerSignature Off

ServerTokens Prod

Now to customize the sig, there is a function called ap_psignature, this is what generates the ServerSignature default footer.  I never intended to use the "Email" feature of the signature, so I removed it.

This is what the function looks like after I've modified it to include a link to the homepage of the site (source version 2.2.10), change to suit.
Open: server/core.c
Look for: ap_psignature

AP_DECLARE(const char *) ap_psignature(const char *prefix, request_rec *r)
{
    char sport[20];
    core_dir_config *conf;
 
    conf = (core_dir_config *)ap_get_module_config(r->per_dir_config,
                                                   &core_module);
    if ((conf->server_signature == srv_sig_off)
            || (conf->server_signature == srv_sig_unset)) {
        return "";
    }
 
    apr_snprintf(sport, sizeof sport, "%u", (unsigned) ap_get_server_port(r));
    return apr_pstrcat(r-&gt;pool, prefix, " Visit our homepage: <a href="&quot;,
                       ap_escape_html(r-&gt;pool, ap_get_server_name(r)),
                       &quot;\&quot;&gt;&quot; , ap_escape_html(r-&gt;pool, ap_get_server_name(r)) , &quot;&lt;/a&gt;&quot;,
                       &quot;\n&quot;, NULL);
}
 

To always display the default footer, even when a Readme file is used (it will appear below the readme block).
Open: modules/generators/mod_autoindex.c
Find this and comment it out:

 
if (!suppress_sig) {
ap_rputs(ap_psignature("", r), r);
}
 

Now you want to build the application as you normally would when compiling from source.  Start it up after the install and you should see your message appear on generated autoindex pages! Changing the source is never a first option, but luckily Apache is open source and easy to modify!

So without further ado:

 
$file = "source.js";
$grep = system("grep -hEo \"^\s*function \w+\" $file | sort | uniq -d");
$functions = split("\n", $grep);
// I'd recommend taking a look at the functions to ensure $functions seems consistent with your data & goals
 
$blob = file_get_contents();
foreach ($functions as $function) {
    $start = strpos($javascript, $function);
 
    // loop through each char until we get to the close bracket
    $stack = array();
    for ($i = $start, $j = strlen($javascript); $i < $j; ++$i) {
        $letter = substr($javascript, $i, 1);
        if ($letter == "{") {
            $stack[] = "true";
        } elseif ($letter == "}") {
            array_shift($stack);
            if (count($stack) == 0) { $lastBracket = $i+1; break; }
        }
    }
    //echo substr($javascript, $start, ($lastBracket - $start)) . "\n";
    $javascript = substr($javascript, 0, $start) . substr($javascript, $lastBracket);
}
echo $javascript;
 

To "undo" the closing of a tab, you can press [ctrl]+[shift]+t.  Try it out.

I decided to give it a shot.

When I received the shipment notification from the retailer (J & R Electronics), I logged into the UPS tracking website to see where it was and when it was scheduled for delivery - Friday, January 25, 2008.

So I just logged in this morning to see if I could get details on ETA, and low and behold, this was one of the entries:

preg_match_all("/href=[\'|\"]http:\/\/([a-zA-Z0-9\.\/\?\-\_\:\=]*)[\'|\"]/i", $haystack, $links_array);

This fills an array ($links_array) with any URLs found in $haystack. No more complex than that, though as you can see, regular expressions can be complex in their own right - they're powerful!

Make yourself a personal goal to learn as much about database concepts as you can. Don't limit yourself to MySQL or any one database system for that matter. There are a lot of peculiarities in the way certain features are implemented in certain ways, depending on the engine that you will not find in any other database system.

There is a good advantage you will have by learning about the pros & cons of the available systems. What open source engine is the best for big data sets? Which one is the easiest to cluster with? There are methodologies and best practices you will learn about by seeing how a particular problem is solved in one system versus another.

Definitely familiarize yourself with ACID compliant database and the SQL standard. MySQL is always a popular choice for applications, especially web applications. Unfortunately there are a lot of short-comings and outright hacks you have to do to accomplish certain things. Date manipulation in MySQL has been notoriously clumsy. Other database engines allow you to do arithmetic on date values as easily as writing an algebraic forumula. MySQL took the approach of using arcane functions such as date_add and date_diff. The same goes for languages.

Oracle DBA's make good money if a corporate career is something you seek. Getting certifications and even a computer science degree are common ways people pursue this career path.

A friend of mine told me a great piece of advice during a conversation we once had about marketable business skills. Investing in SQL is the best shot in the arm any "knowledge worker" can do to increase the value they can add to any employer. It is the most ubiquitous, advanced business tool for storing and reporting on business data in this age.

What is the problem?

Given certain input, an application will interpret the input as executable code (either executable in SQL or the language of the application by using input in an "eval" block). There have been numerous high-profile examples of these attacks being used against web sites. The infamous RIAA's website just suffered from one such attack.

What does an attack of this vulnerability look like?

An attack might best be described by this short cartoon:

What is the best practice for sanitizing input?

This is a simplified example of how I do it, in PHP. PHP implements Perl-Compatible Regular Expressions, and any language implementing regular expression syntax (for instance, Perl) in this manner should have a similar snippet of code that effectively does the same thing.

$cleanvar = ereg_replace('[^a-zA-Z0-9]', '', $_POST['var']); // will only allow upper & lower alphas and integers