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ctrl+shift+T
//Switching tabs
ctrl+pageUp
//Also: Switching consoles in linux:
ctrl+alt+F1
ctrl+alt+F2
ctrl+alt+F3
ctrl+alt+F4
ctrl+alt+F5
ctrl+alt+F6
ctrl+alt+F7
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<?php
/*
We'll get the content of a remote page to display locally ;)
*/
$curl=curl_init();
// Set some options - we are passing in a useragent too here
curl_setopt_array($curl, array(
CURLOPT_RETURNTRANSFER => 1,
CURLOPT_URL => 'http://www.televisa.com/us/',
CURLOPT_BINARYTRANSFER=>true,
));
// Send the request & save response to $resp
$resp = curl_exec($curl);
// Close request to clear up some resources
curl_close($curl);
echo $resp;
?>
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SELECT * FROM tablename
WHERE somefield='something'
ORDER BY RAND() LIMIT 5
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INSERT INTO NewTable (col1, col2, col3) SELECT col1, col2, col3 FROM OldTable
Page 985 in MySQL Developer's Library (Paul DuBois), and
http://stackoverflow.com/questions/3140 ... to-another
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//Use the following query:
SELECT DATE(`date_time_field`) AS date_part, TIME(`date_time_field`) AS time_part FROM `your_table`;
//Also you can use:
SELECT DATE_FORMAT(colName,'%Y-%m-%d') DATEONLY,DATE_FORMAT(colName,'%H:%i:%s') TIMEONLY FROM `your_table`;
http://stackoverflow.com/questions/1233 ... e-in-mysql
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$current_time = strtotime('now');
if ($current_time > strtotime('wednesday this week 8:00pm') && $current_time < strtotime('thursday this week 2:00am')) {
// Special logo
}
http://stackoverflow.com/questions/5413 ... ther-times
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//non namespaced attributes
<?php
$data=<<<XML
<rss version="2.0" xmlns:media="http://search.yahoo.com/mrss/">
<channel>
<item>
<title>Title: 0</title>
<link test="test" test2="This is a test">Link:0</link>
<media:thumbnail url="0"/>
<media:content url="0" type="video/mp4" />
</item>
<item>
<title>Title: 1</title>
<link>Link:1</link>
<media:thumbnail url="1"/>
<media:content url="1" type="video/mp4" />
</item>
<item>
<title>Title: 2</title>
<link>Link:2</link>
<media:thumbnail url="2"/>
<media:content url="2" type="video/mp4" />
</item>
<item>
<title>Title: 3</title>
<link>Link:3</link>
<media:thumbnail url="3"/>
<media:content url="3" type="video/mp4" />
</item>
</channel>
</rss>
XML;
$xml=simplexml_load_string($data);
echo $xml->channel[0]->item[0]->title."<br>";
echo $xml->channel[0]->item[0]->link->attributes()->test2="This is a NEW test!.";
//Creates update.xml with updated test2 value
$xml->asXml('updated.xml');
?>
===============================================================================
//namespaced attributes
<?php
$data=<<<XML
<rss version="2.0" xmlns:media="http://search.yahoo.com/mrss/">
<channel>
<item>
<title>Title: 0</title>
<link test="test" test2="This is a test">Link:0</link>
<media:thumbnail url="Thumbnail URL: 0"/>
<media:content url="Content URL: 0" type="video/mp4" />
</item>
<item>
<title>Title: 1</title>
<link>Link:1</link>
<media:thumbnail url="1"/>
<media:content url="1" type="video/mp4" />
</item>
</channel>
</rss>
XML;
$xml=simplexml_load_string($data);
//reading simple node
echo $xml->channel[0]->item[0]->title;
echo "<br>----------------------------------<br>";
//reading/updating simple node's attribute
echo $xml->channel[0]->item[0]->link->attributes()->test2="This is a NEW test!.";
echo "<br>----------------------------------<br>";
//reading/updating namespaced node's attribute
echo $xml->channel[0]->item[0]->children('media',TRUE)->content->attributes()->type="VIDEO/MP6";
//saving...
$xml->asXml('updated.xml');
?>
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<?php
$xml_content= <<<XML
<rss version="2.0" xmlns:media="http://search.yahoo.com/mrss/">
<channel>
XML;
for($i=0;$i<=8;$i++){
$xml_content.=<<<XML
<item>
<title>$i</title>
<link>$i</link>
<media:thumbnail url="$i"/>
<media:content url="$i" type="video/mp4" />
</item>
XML;
}
$xml_content.=<<<XML
</channel>
</rss>
XML;
echo $xml_content;
//use {$...} to embed variables in heredoc
?>
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In JavaScript is not as easy to set and read a cookie, as it is in PHP; the functions below ease my day when performing these tasks in JS. Alternatively jQuery can be used.
//JS cookie format
document.cookie = "name=value; expires=date; path=path;domain=domain; secure";
//date format
Based on testing and further reading into this, a date in a UTC/GMT format is required by cookies e.g. Sun, 15 Jul 2012 00:00:01 GMT
Therefore any dates in other formats such as 15 Jul 2012, or 15/Jul/2012, or 07/15/2012, have to be passed as a new Date object and then through the toUTCString() or the toGMTString() function.
/*Tested by me: OK*****************************************************************/
/*
name - name of the cookie
value - value of the cookie
[expires] - expiration date of the cookie
(defaults to end of current session)
[path] - path for which the cookie is valid
(defaults to path of calling document)
[domain] - domain for which the cookie is valid
(defaults to domain of calling document)
[secure] - Boolean value indicating if the cookie transmission requires
a secure transmission
* an argument defaults when it is assigned null as a placeholder
* a null placeholder is not required for trailing omitted arguments
*/
function setCookie(name, value, expires, path, domain, secure) {
var curCookie = name + "=" + escape(value) +
((expires) ? "; expires=" + expires.toGMTString() : "") +
((path) ? "; path=" + path : "") +
((domain) ? "; domain=" + domain : "") +
((secure) ? "; secure" : "");
document.cookie = curCookie;
}
//SET COOKIE
var days=90;
var date = new Date();
date.setTime(date.getTime()+(days*24*60*60*1000));
setCookie("SignedUp","true",date,"/");
/*Tested by me: OK*****************************************************************/
/*
name - name of the desired cookie
return string containing value of specified cookie or null
if cookie does not exist
*/
function getCookie(name) {
var dc = document.cookie;
var prefix = name + "=";
var begin = dc.indexOf("; " + prefix);
if (begin == -1) {
begin = dc.indexOf(prefix);
if (begin != 0) return null;
} else
begin += 2;
var end = document.cookie.indexOf(";", begin);
if (end == -1)
end = dc.length;
return unescape(dc.substring(begin + prefix.length, end));
}
/*****************************************************************/
/*
name - name of the cookie
[path] - path of the cookie (must be same as path used to create cookie)
[domain] - domain of the cookie (must be same as domain used to
create cookie)
path and domain default if assigned null or omitted if no explicit
argument proceeds
*/
function deleteCookie(name, path, domain) {
if (getCookie(name)) {
document.cookie = name + "=" +
((path) ? "; path=" + path : "") +
((domain) ? "; domain=" + domain : "") +
"; expires=Thu, 01-Jan-70 00:00:01 GMT";
}
}
/*****************************************************************/
// date - any instance of the Date object
// * hand all instances of the Date object to this function for "repairs"
function fixDate(date) {
var base = new Date(0);
var skew = base.getTime();
if (skew > 0)
date.setTime(date.getTime() - skew);
}
See:
http://www.webreference.com/js/column8/functions.html
http://www.elated.com/articles/javascript-and-cookies/
http://stackoverflow.com/questions/1113 ... ing-a-cook
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CentOS has an extremely powerful firewall built in, commonly referred to as iptables, but more accurately is iptables/netfilter. Iptables is the userspace module, the bit that you, the user, interact with at the command line to enter firewall rules into predefined tables. Netfilter is a kernel module, built into the kernel, that actually does the filtering. There are many GUI front ends for iptables that allow users to add or define rules based on a point and click user interface, but these often lack the flexibility of using the command line interface and limit the users understanding of what's really happening. We're going to learn the command line interface of iptables.
Before we can really get to grips with iptables, we need to have at least a basic understanding of the way it works. Iptables uses the concept of IP addresses, protocols (tcp, udp, icmp) and ports. We don't need to be experts in these to get started (as we can look up any of the information we need), but it helps to have a general understanding.
Iptables places rules into predefined chains (INPUT, OUTPUT and FORWARD) that are checked against any network traffic (IP packets) relevant to those chains and a decision is made about what to do with each packet based upon the outcome of those rules, i.e. accepting or dropping the packet. These actions are referred to as targets, of which the two most common predefined targets are DROP to drop a packet or ACCEPT to accept a packet.
Chains
These are 3 predefined chains in the filter table to which we can add rules for processing IP packets passing through those chains. These chains are:
INPUT - All packets destined for the host computer.
OUTPUT - All packets originating from the host computer.
FORWARD - All packets neither destined for nor originating from the host computer, but passing through (routed by) the host computer. This chain is used if you are using your computer as a router.
For the most part, we are going to be dealing with the INPUT chain to filter packets entering our machine - that is, keeping the bad guys out.
Rules are added in a list to each chain. A packet is checked against each rule in turn, starting at the top, and if it matches that rule, then an action is taken such as accepting (ACCEPT) or dropping (DROP) the packet. Once a rule has been matched and an action taken, then the packet is processed according to the outcome of that rule and isn't processed by further rules in the chain. If a packet passes down through all the rules in the chain and reaches the bottom without being matched against any rule, then the default action for that chain is taken. This is referred to as the default policy and may be set to either ACCEPT or DROP the packet.
The concept of default policies within chains raises two fundamental possibilities that we must first consider before we decide how we are going to organize our firewall.
1. We can set a default policy to DROP all packets and then add rules to specifically allow (ACCEPT) packets that may be from trusted IP addresses, or for certain ports on which we have services running such as bittorrent, FTP server, Web Server, Samba file server etc.
or alternatively,
2. We can set a default policy to ACCEPT all packets and then add rules to specifically block (DROP) packets that may be from specific nuisance IP addresses or ranges, or for certain ports on which we have private services or no services running.
Generally, option 1 above is used for the INPUT chain where we want to control what is allowed to access our machine and option 2 would be used for the OUTPUT chain where we generally trust the traffic that is leaving (originating from) our machine.
We will use an example based approach to examine the various iptables commands. In this first example, we will create a very simple set of rules to set up a Stateful Packet Inspection (SPI) firewall that will allow all outgoing connections but block all unwanted incoming connections:
# iptables -P INPUT ACCEPT
# iptables -F
# iptables -A INPUT -i lo -j ACCEPT
# iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
# iptables -A INPUT -p tcp --dport 22 -j ACCEPT
# iptables -P INPUT DROP
# iptables -P FORWARD DROP
# iptables -P OUTPUT ACCEPT
# iptables -L -v
which should give the following output:
Chain INPUT (policy DROP 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 ACCEPT all -- lo any anywhere anywhere
0 0 ACCEPT all -- any any anywhere anywhere state RELATED,ESTABLISHED
0 0 ACCEPT tcp -- any any anywhere anywhere tcp dpt:ssh
Chain FORWARD (policy DROP 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Now lets look at each of the 8 commands above in turn and understand exactly what we've just done:
iptables -P INPUT ACCEPT
If connecting remotely we must first temporarily set the default policy on the INPUT chain to ACCEPT otherwise once we flush the current rules we will be locked out of our server.
iptables -F
We used the -F switch to flush all existing rules so we start with a clean state from which to add new rules.
iptables -A INPUT -i lo -j ACCEPT
Now it's time to start adding some rules. We use the -A switch to append (or add) a rule to a specific chain, the INPUT chain in this instance. Then we use the -i switch (for interface) to specify packets matching or destined for the lo (localhost, 127.0.0.1) interface and finally -j (jump) to the target action for packets matching the rule - in this case ACCEPT. So this rule will allow all incoming packets destined for the localhost interface to be accepted. This is generally required as many software applications expect to be able to communicate with the localhost adaptor.
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
This is the rule that does most of the work, and again we are adding (-A) it to the INPUT chain. Here we're using the -m switch to load a module (state). The state module is able to examine the state of a packet and determine if it is NEW, ESTABLISHED or RELATED. NEW refers to incoming packets that are new incoming connections that weren't initiated by the host system. ESTABLISHED and RELATED refers to incoming packets that are part of an already established connection or related to and already established connection.
iptables -A INPUT -p tcp --dport 22 -j ACCEPT
Here we add a rule allowing SSH connections over tcp port 22. This is to prevent accidental lockouts when working on remote systems over an SSH connection. We will explain this rule in more detail later.
iptables -P INPUT DROP
The -P switch sets the default policy on the specified chain. So now we can set the default policy on the INPUT chain to DROP. This means that if an incoming packet does not match one of the following rules it will be dropped. If we were connecting remotely via SSH and had not added the rule above, we would have just locked ourself out of the system at this point.
iptables -P FORWARD DROP Similarly, here we've set the default policy on the FORWARD chain to DROP as we're not using our computer as a router so there should not be any packets passing through our computer.
iptables -P OUTPUT ACCEPT
and finally, we've set the default policy on the OUTPUT chain to ACCEPT as we want to allow all outgoing traffic (as we trust our users).
iptables -L -v Finally, we can list (-L) the rules we've just added to check they've been loaded correctly.
Finally, the last thing we need to do is save our rules so that next time we reboot our computer our rules are automatically reloaded:
# /sbin/service iptables save
==================================================
See: http://wiki.centos.org/HowTos/Network/IPTables
See ip6tables command.
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