Tag Archives: Amazon EC2

Stopping and investigating a WordPress xmlrpc.php attack

One of my Servers got heavily attacked for several days. I describe here the steps I took to stop this.

The attack consisted in several connections per second to the Server, to path /xmlrpc.php.

This is a WordPress file to control the pingback, when someone links to you.

My Server it is a small Amazon instance, a m1.small with only one core and 1,6 GB RAM, magnetic disks and that scores a discrete 203 CMIPS (my slow laptop scores 460 CMIPS).

Those massive connections caused the server to use more and more RAM, and while the xmlrpc requests were taking many seconds to reply, so more and more processes of Apache were spawned. That lead to more memory consumption, and to use all the available RAM and start using swap, with a heavy performance impact until all the memory was exhausted and the mysql processes stopped.

I saw that I was suffering an attack after the shutdown of MySql. I checked the CloudWatch Statistics from Amazon AWS and it was clear that I was receiving many -out of normal- requests. The I/O was really high too.

This statistics are from today to three days ago, look at the spikes when the attack was hitting hard and how relaxed the Server is now (plain line).

blog-carlesmateo-com-statistics-use-last-3-days

First I decided to simply rename the xmlrpc.php file as a quick solution to stop the attack but the number of http connections kept growing and then I saw very suspicious queries to the database.

blog-carlesmateo-suspicious-queries-2014-08-30-00-11-59Those queries, in addition to what I’ve seen in the Apache’s error log suggested me that may be the Server was hacked by a WordPress/plugin bug and that now they were trying to hide from the database’s logs. (Specially the DELETE FROM wp_useronline WHERE user_ip = the Ip of the attacker)

[Tue Aug 26 11:47:08 2014] [error] [client 94.102.49.179] Error in WordPress Database Lost connection to MySQL server during query a la consulta SELECT option_value FROM wp_options WHERE option_name = 'uninstall_plugins' LIMIT 1 feta per include('wp-load.php'), require_once('wp-config.php'), require_once('wp-settings.php'), include_once('/plugins/captcha/captcha.php'), register_uninstall_hook, get_option
[Tue Aug 26 11:47:09 2014] [error] [client 94.102.49.179] Error in WordPress Database Lost connection to MySQL server during query a la consulta SELECT option_value FROM wp_options WHERE option_name = 'uninstall_plugins' LIMIT 1 feta per include('wp-load.php'), require_once('wp-config.php'), require_once('wp-settings.php'), include_once('/plugins/captcha/captcha.php'), register_uninstall_hook, get_option
[Tue Aug 26 11:47:10 2014] [error] [client 94.102.49.179] Error in WordPress Database Lost connection to MySQL server during query a la consulta SELECT option_value FROM wp_options WHERE option_name = 'widget_wppp' LIMIT 1 feta per include('wp-load.php'), require_once('wp-config.php'), require_once('wp-settings.php'), do_action('plugins_loaded'), call_user_func_array, wppp_check_upgrade, get_option

The error log was very ugly.

The access log was not reassuring, as it shown many attacks like that:

94.102.49.179 - - [26/Aug/2014:10:34:58 +0000] "POST /xmlrpc.php HTTP/1.0" 200 598 "-" "Mozilla/4.0 (compatible: MSIE 7.0; Windows NT 6.0)"
94.102.49.179 - - [26/Aug/2014:10:34:59 +0000] "POST /xmlrpc.php HTTP/1.0" 200 598 "-" "Mozilla/4.0 (compatible: MSIE 7.0; Windows NT 6.0)"
127.0.0.1 - - [26/Aug/2014:10:35:09 +0000] "OPTIONS * HTTP/1.0" 200 126 "-" "Apache/2.2.22 (Ubuntu) (internal dummy connection)"
94.102.49.179 - - [26/Aug/2014:10:34:59 +0000] "POST /xmlrpc.php HTTP/1.0" 200 598 "-" "Mozilla/4.0 (compatible: MSIE 7.0; Windows NT 6.0)"
94.102.49.179 - - [26/Aug/2014:10:34:59 +0000] "POST /xmlrpc.php HTTP/1.0" 200 598 "-" "Mozilla/4.0 (compatible: MSIE 7.0; Windows NT 6.0)"
94.102.49.179 - - [26/Aug/2014:10:35:00 +0000] "POST /xmlrpc.php HTTP/1.0" 200 598 "-" "Mozilla/4.0 (compatible: MSIE 7.0; Windows NT 6.0)"
94.102.49.179 - - [26/Aug/2014:10:34:59 +0000] "POST /xmlrpc.php HTTP/1.0" 200 598 "-" "Mozilla/4.0 (compatible: MSIE 7.0; Windows NT 6.0)"

Was difficult to determine if the Server was receiving SQL injections so I wanted to be sure.

Note: The connection from 127.0.0.1 with OPTIONS is created by Apache when spawns another Apache.

As I had super fresh backups in another Server I was not afraid of the attack dropping the database.

I was a bit suspicious also because the /readme.html file mentioned that the version of WordPress is 3.6. In other installations it tells correctly that the version is the 3.9.2 and this file is updated with the auto-update. I was thinking about a possible very sophisticated trojan attack able to modify wp-includes/version.php and set fake $wp_version = ‘3.9.2’;
Later I realized that this blog had WordPress in Catalan, my native language, and discovered that the guys that do the translations forgot to update this file (in new installations it comes not updated, and so showing 3.6). I have alerted them.

In fact later I did a diff of all the files of my WordPress installation against the official WordPress 3.9.2-ca and later a did a diff between the WordPress 3.9.2-ca and the WordPress 3.9.2 (English – default), and found no differences. My Server was Ok. But at this point, at the beginning of the investigation I didn’t know that yet.

With the info I had (queries, times, attack, readme telling v. 3.6…) I balanced the possibility to be in front of something and I decided that I had an unique opportunity to discover how they do to inject those Sql, or discover if my Server was compromised and how. The bad point is that it was the same Amazon’s Server where this blog resides, and I wanted the attack to continue so I could get more information, so during two days I was recording logs and doing some investigations, so sorry if you visited my blog and database was down, or the Server was going extremely slow. I needed that info. It was worth it.

First I changed the Apache config so the massive connections impacted a bit less the Server and so I could work on it while the attack was going on.

I informed my group of Senior friends on what’s going on and two SysAdmins gave me some good suggestions on other logs to watch and on how to stop the attack, and later a Developer joined me to look at the logs and pointed possible solutions to stop the attack. But basically all of them suggested on how to block the incoming connections with iptables and to do things like reinstalling WordPress, disabling xmlrpc.php in .htaccess, changing passwords or moving wp-admin/ to another place, but the point is that I wanted to understand exactly what was going on and how.

I checked the logs, certificates, etc… and no one other than me was accessing the Server. I also double-checked the Amazon’s Firewall to be sure that no unnecessary ports were left open. Everything was Ok.

I took a look at the Apache logs for the site and all the attacks were coming from the same Ip:

94.102.49.179

It is an Ip from a dedicated Servers company called ecatel.net. I reported them the abuse to the abuse address indicated in the ripe.net database for the range.

I found that many people have complains about this provider and reports of them ignoring the requests to stop the spam use from their servers, so I decided that after my tests I will block their entire network from being able to access my sites.

All the requests shown in the access.log pointed to requests to /xmlrpc.php. It was the only path requested by the attacker so that Ip did nothing more apparently.

I added some logging to WordPress xmlrpc.php file:

if ($_SERVER['REMOTE_ADDR'] == '94.102.49.179') {
    error_log('XML POST: '.serialize($_POST));
    error_log('XML GET: '.serialize($_GET));
    error_log('XML REQUEST: '.serialize($_REQUEST));
    error_log('XML SERVER: '.serialize($_SERVER));
    error_log('XML FILES: '.serialize($_FILES));
    error_log('XML ENV: '.serialize($_ENV));
    error_log('XML RAW: '.$HTTP_RAW_POST_DATA);
    error_log('XML ALL_HEADERS: '.serialize(getallheaders()));
}

This was the result, it is always the same:

[Fri Aug 29 19:02:54 2014] [error] [client 94.102.49.179] XML POST: a:0:{}
[Fri Aug 29 19:02:54 2014] [error] [client 94.102.49.179] XML GET: a:0:{}
[Fri Aug 29 19:02:54 2014] [error] [client 94.102.49.179] XML REQUEST: a:0:{}
[Fri Aug 29 19:02:54 2014] [error] [client 94.102.49.179] XML SERVER: a:24:{s:9:"HTTP_HOST";s:24:"barcelona.afterstart.com";s:12:"CONTENT_TYPE";s:8:"text/xml";s:14:"CONTENT_LENGTH";s:3:"287";s:15:"HTTP_USER_AGENT";s:50:"Mozilla/4.0 (compatible: MSIE 7.0; Windows NT 6.0)";s:15:"HTTP_CONNECTION";s:5:"close";s:4:"PATH";s:28:"/usr/local/bin:/usr/bin:/bin";s:16:"SERVER_SIGNATURE";s:85:"<address>Apache/2.2.22 (Ubuntu) Server at barcelona.afterstart.com Port 80</address>\n";s:15:"SERVER_SOFTWARE";s:22:"Apache/2.2.22 (Ubuntu)";s:11:"SERVER_NAME";s:24:"barcelona.afterstart.com";s:11:"SERVER_ADDR";s:14:"[this-is-removed]";s:11:"SERVER_PORT";s:2:"80";s:11:"REMOTE_ADDR";s:13:"94.102.49.179";s:13:"DOCUMENT_ROOT";s:29:"/var/www/barcelona.afterstart.com";s:12:"SERVER_ADMIN";s:19:"webmaster@localhost";s:15:"SCRIPT_FILENAME";s:40:"/var/www/barcelona.afterstart.com/xmlrpc.php";s:11:"REMOTE_PORT";s:5:"40225";s:17:"GATEWAY_INTERFACE";s:7:"CGI/1.1";s:15:"SERVER_PROTOCOL";s:8:"HTTP/1.0";s:14:"REQUEST_METHOD";s:4:"POST";s:12:"QUERY_STRING";s:0:"";s:11:"REQUEST_URI";s:11:"/xmlrpc.php";s:11:"SCRIPT_NAME";s:11:"/xmlrpc.php";s:8:"PHP_SELF";s:11:"/xmlrpc.php";s:12:"REQUEST_TIME";i:1409338974;}
[Fri Aug 29 19:02:54 2014] [error] [client 94.102.49.179] XML FILES: a:0:{}
[Fri Aug 29 19:02:54 2014] [error] [client 94.102.49.179] XML ENV: a:0:{}
[Fri Aug 29 19:02:54 2014] [error] [client 94.102.49.179] XML RAW: <?xmlversion="1.0"?><methodCall><methodName>pingback.ping</methodName><params><param><value><string>http://seretil.me/</string></value></param><param><value><string>http://barcelona.afterstart.com/2013/09/27/afterstart-barcelona-2013-09-26/</string></value></param></params></methodCall>
[Fri Aug 29 19:02:54 2014] [error] [client 94.102.49.179] XML ALL_HEADERS: a:5:{s:4:"Host";s:24:"barcelona.afterstart.com";s:12:"Content-type";s:8:"text/xml";s:14:"Content-length";s:3:"287";s:10:"User-agent";s:50:"Mozilla/4.0 (compatible: MSIE 7.0; Windows NT 6.0)";s:10:"Connection";s:5:"close";}

So nothing in $_POST, nothing in $_GET, nothing in $_REQUEST, nothing in $_SERVER, no files submitted, but a text/xml Posted (that was logged by storing: $HTTP_RAW_POST_DATA):

<?xmlversion="1.0"?><methodCall><methodName>pingback.ping</methodName><params><param><value><string>http://seretil.me/</string></value></param><param><value><string>http://barcelona.afterstart.com/2013/09/27/afterstart-barcelona-2013-09-26/</string></value></param></params></methodCall>

I show you in a nicer formatted aspect:blog-carlesmateo-com-xml-xmlrpc-requestSo basically they were trying to register a link to seretil dot me.

I tried and this page, hosted in CloudFare, is not working.

accessing-seretil-withoud-id

The problem is that responding to this spam xmlrpc request took around 16 seconds to the Server. And I was receiving several each second.

I granted access to my Ip only on the port 80 in the Firewall, restarted Apache, restarted MySql and submitted the same malicious request to the Server, and it even took 16 seconds in all my tests:

cat http_post.txt | nc barcelona.afterstart.com 80

blog-carlesmateo-com-response-from-the-server-to-xmlrpc-attackI checked and confirmed that the logs from the attacker were showing the same Content-Length and http code.

Other guys tried xml request as well but did one time or two and leaved.

The problem was that this robot was, and still sending many requests per second for days.

May be the idea was to knock down my Server, but I doubted it as the address selected is the blog of one Social Event for Senior Internet Talents that I organize: afterstart.com. It has not special interest, I do not see a political, hateful or other motivation to attack the blog from this project.

Ok, at this point it was clear that the Ip address was a robot, probably running from an infected or hacked Server, and was trying to publish a Spam link to a site (that was down). I had to clarify those strange queries in the logs.

I reviewed the WPUsersOnline plugin and I saw that the strange queries (and inefficient) that I saw belonged to WPUsersOnline plugin.

blog-carlesmateo-com-grep-r-delete-from-wp-useronline-2014-08-30-21-11-21-cut

The thing was that when I renamed the xmlrpc.php the spamrobot was still posting to that file. According to WordPress .htaccess file any file that is not found on the filesystem is redirected to index.php.

So what was happening is that all the massive requests sent to xmlrpc.php were being attended by index.php, then showing an error message that page not found, but the WPUsersOnline plugin was deleting those connections. And was doing it many times, overloading also the Database.

Also I was able to reproduce the behaviour by myself, isolating by firewalling the WebServer from other Ips other than mine and doing the same post by myself many times per second.

I checked against a friend’s blog but in his Server xmlrpc.php responds in 1,5 seconds. My friend’s Server is a Digital Ocean Virtual Server with 2 cores and SSD Disks. My magnetic disks on Amazon only bring around 40 MB/second. I’ve to check in detail why my friend’s Server responds so much faster.

Checked the integrity of my databases, just in case, and were perfect. Nothing estrange with collations and the only errors in the /var/log/mysql/error.log was due to MySql crashing when the Server ran out of memory.

Rechecked in my Server, now it takes 12 seconds.

I disabled 80% of the plugins but the times were the same. The Statistics show how the things changed -see the spikes before I definitively patched the Server to block request from that Spam-robot ip, to the left-.

I checked against another WordPress that I have in the same Server and it only takes 1,5 seconds to reply. So I decided to continue investigating why this WordPress took so long to reply.

blog-carlesmateo-com-statistics-use-last-24-hours

As I said before I checked that the files from my WordPress installation were the same as the original distribution, and they were. Having discarded different files the thing had to be in the database.

Even when I checked the MySql it told me that all the tables were OK, having seen that the WPUserOnline deletes all the registers older than 5 minutes, I guessed that this could lead to fragmentation, so I decided to do OPTIMIZE TABLE on all the tables of the database for the WordPress failing, with InnoDb it is basically recreating the Tables and the Indexes.

I tried then the call via RPC and my Server replied in three seconds. Much better.

Looking with htop, when I call the xmlrpc.php the CPU uses between 50% and 100%.

I checked the logs and the robot was gone. He leaved or the provider finally blocked the Server. I don’t know.

Everything became clear, it was nothing more than a sort of coincidences together. Deactivating the plugin the DELETE queries disappeared, even under heavy load of the Server.

It only was remain to clarify why when I send a call to xmlrpc to this blog, it replies in 1,5 seconds, and when I request to the Barcelona.afterstart.com it takes 3 seconds.

I activated the log of queries in mysql. To do that edit /etc/mysql/my.cnf and uncomment:

general_log_file        = /var/log/mysql/mysql.log
general_log             = 1

Then I checked the queries, and in the case of my blog it performs many less queries, as I was requesting to pingback to an url that was not existing, and WordPress does this query:

SELECT   wp_posts.* FROM wp_posts  WHERE 1=1  AND ( ( YEAR( post_date ) = 2013 AND MONTH( post_date ) = 9 AND DAYOFMONTH( post_date ) = 27 ) ) AND wp_posts.post_name = 'afterstart-barcelona-2013-09-26-meet' AND wp_posts.post_type = 'post'  ORDER BY wp_posts.post_date DESC

As the url afterstart-barcelona-2013-09-26-meet with the dates indicated does not exist in my other blog, the execution ends there and does not perform the rest of the queries, that in the case of Afterstart blog were:

40 Query     SELECT post_id, meta_key, meta_value FROM wp_postmeta WHERE post_id IN (81) ORDER BY meta_id ASC
40 Query     SELECT ID, post_name, post_parent, post_type
FROM wp_posts
WHERE post_name IN ('http%3a','','seretil-me')
AND post_type IN ('page','attachment')
40 Query     SELECT   wp_posts.* FROM wp_posts  WHERE 1=1  AND (wp_posts.ID = '0') AND wp_posts.post_type = 'page'  ORDER BY wp_posts.post_date DESC
40 Query     SELECT * FROM wp_comments WHERE comment_post_ID = 81 AND comment_author_url = 'http://seretil.me/'

To confirm my theory I tried the request to my blog, with a valid url, and it lasted for 3-4 seconds, the same than Afterstart’s blog. Finally I double-checked with the blog of my friend and was slower than before. I got between 1,5 and 6 seconds, with a lot of 2 seconds response. (he has PHP 5.5 and OpCache that improves a bit, but the problem is in the queries to the database)

Honestly, the guys creating WordPress should cache this queries instead of performing 20 live queries, that are always the same, before returning the error message. Using Cache Lite or Stash, or creating an InMemory table for using as Cache, or of course allowing the use of Memcached would eradicate the DoS component of this kind of attacks. As the xmlrpc pingback feature hits the database with a lot of queries to end not allowing the publishing.

While I was finishing those tests (remember that the attacker ip has gone) another attacker from the same network tried, but I had patched the Server to ignore it:

94.102.52.157 - - [31/Aug/2014:02:06:16 +0000] "POST /xmlrpc.php HTTP/1.0" 200 189 "-" "Mozilla/4.0 (compatible: MSIE 7.0; Windows NT 6.0)"

This was trying to get a link published to a domain called socksland dot net that is a domain registered in Russia and which page is not working.

As I had all the information I wanted I finally blocked the network from the provider to access my Server ever again.

Unfortunatelly Amazon’s Firewall does not allow to block a certain Ip or range.
So you can block at Iptables level or in .htaccess file or in the code.
I do not recommend blocking at code level because sadly WordPress has many files accessible from outside so you would have to add your code at the beginning of all the files and because when there is a WordPress version update you’ll loss all your customizations.
But I recommend proceeding to patch your code to avoid certain Ip’s if you use a CDN. As the POST will be sent directly to your Server, and the Ip’s are Ip’s from the CDN -and you can’t block them-. You have to look at the Header: X-Forwarded-For that indicates the Ip’s the proxies have passed by, and also the Client’s Ip.

I designed a program that is able to patch any PHP project to check for blacklisted Ip’s (even though a proxy) with minimal performance impact. It works with WordPress, drupal, joomla, ezpublish and Framework like Zend, Symfony, Catalonia… and I patched my code to block those unwanted robot’s requests.

A solution that will work for you probably is to disable the pingback functionality, there are several plugins that do that. Disabling completely xmlrpc is not recommended as WordPress uses it for several things (JetPack, mobile, validation…)

The same effect as adding the plugin that disables the xmlrpc pingback can be achieved by editing the functions.php from your Theme and adding:

add_filter( 'xmlrpc_methods', 'remove_xmlrpc_pingback_ping' );
function remove_xmlrpc_pingback_ping( $methods ) {
    unset( $methods['pingback.ping'] );
    
    return $methods;
}

Update: 2016-02-24 14:40 CEST
I got also a heavy dictionary attack against wp-login.php .Despite having a Captcha plugin, that makes it hard to hack, it was generating some load on the system.
What I did was to rename the wp-login.php to another name, like wp-login-carles.php and in wp-login.php having a simply exit();

<?php
exit();

The Cloud is for Scaling

dell-blades-m4110The Cloud is for Startups, and for Scaling. Nothing more.

In the future will be used by phone operators, to re-dimension their infrastructure and bandwidth in real time according to demand, but nowadays the Cloud is for Startups.

Examine the prices in my post in cmips, take a look, examine the performance also of the different CPU. You see that according to CMIPS v.1.03 a Desktop Processor Intel i7-4770S, worth USD $300, performs better than an Amazon M2 High Memory Quadruple Extra Large and than a Rackspace First gen. 30 GB RAM 8 Cores?.

Today the public cost of an Amazon M2 High Memory Quadruple Extra Large running for a month is USD $1,180.80 so USD $1.64 per hour and the Rackspace First Generation 30 GB RAM 8 Cores 1200 GB of disk costs is USD $1,425.60 so USD $1.98 per hour running.

And that’s the key, the cost per hour.

Because the greatness, the majesty of the Cloud is that you pay per hour, you pay as you need, or as you go. No attaching contracts. All on demand.

I had my company at a time where the hosting companies and the Data Centers were forcing customers to sign yearly contracts. What if a company only needs to host their Servers for three months? What if they have to close?. No options. You take it or you leave it.

Even renting a dedicated hosting was for at least a month or more, and what if the latency was not good? What if the bandwidth of the provider was not enough?.

Amazon irrupted in the market with strength. I really like that company because they grew the best eCommerce company for buying books, they did a system that really worked, and was able to recommend very useful computer books, and the delivery, logistics was so good, also post-sales service. They simply started to rent the same infrastructure they were using to attend their millions of customers and was a total success.

And for a while few people knew about Amazon deep technologies and functionalities, but later became a fashion.

Now people is using Amazon or whatever provider/Service that contains the word “Cloud” because the Cloud is in the mouth of everyone. Magazines and newspapers speak about the Cloud, so many many companies use it simply because everyone is talking about the Cloud. And those ISP that didn’t had a Cloud have invested heavily to create a Cloud, just because they didn’t want to be the ones without a Cloud, since everyone was asking for it and all the ISP companies were offering their “Clouds”.

Every company claims to have “Cloud” where the only many of them have is Vmware servers, Xen servers, Open Stack… running the tenants or instances of the customers always on the same host servers. No real Cloud, professional Cloud, abstract layered in a Professional way like Amazon, only the traditional “shared hosting” with another name, sharing CPU and RAM and Disk storage using virtual machines called instances.

So, Cloud fashion has become a confusing craziness where no one knows why they are in the Cloud but they believe they have to be in.

But do companies need the Cloud?. Cloud instances?

It depends. The best would be to ask that companies Why you choose the Cloud?.

If you compare the cost of having an instance in the Cloud, is much much more expensive than having a dedicated server. And for that high cost you don’t get more performance.

Virtualization is always slower and disk speed is always an issue in Cloud providers, where all the data travels via network from the disk cabins NAS to the Host servers running the guest instances. Data cannot be at local disks, since every time you start an instance, the resources like CPU and RAM are provisioned, and your instance run in totally different hardware. Only your data remain in the NAS (Network Attached Storage).

So unless you run your in-the-Cloud instance in a special provider that offers local disks, like DigitalOcean that offers SSD but monthly paying, (and so you pay the price by losing the hardware abstraction capability because you’re attached to the CPU that has the disk connected, and also you loss the flexibility of paying per hour of use, as you go), then you’ll face a bottleneck that is the hard disk performance (that for real takes all the data from NAS, where is stored, through the local network).

So what are the motivations to use the Cloud?. I try to put some examples, out of these it has no much sense, I think. You can send me your happy-in-Cloud scenarios if you found other good uses.

Example A) Saving initial costs, avoid contract attachment and grow easily own-made

Imagine a Developer that start its own project. May be it works, may be not, but instead of having a monthly contract for a dedicated server, he starts with an Amazon Free Tier (better not, use Small instance at least) and runs a web. If it does not work, simply stop the instance and pay no more. If the project works and has more and more users he can re-dimension the server with a click. Just stop the instance, change the type of instance, start it again with more RAM and more CPU power. Fast.

Hiring a dedicated server implies at least monthly contracts, average of USD $100 per month, and is not easy to move to a bigger server, not fast and is expensive as it requires the ISP tech guys to move the data, to migrate from a Server to another.

Also the available bandwidth is to be taken in consideration. Bandwidth is expensive and Amazon can offer 150 Mbit to smaller machines. Not all the Internet Service Providers can offer that bandwidth even with most advanced packets.

If the project still grows, with a click, in seconds, 20 instances with a lot of bandwidth can be deployed and serving traffic to your customers very quick.

You save the init costs of buying Servers, and the time to deal with hardware, bandwidth limitations and avoid contracts, but you pay an hourly rate a lot more expensive. So in the long run is much much expensive using Amazon and less powerful than having dedicated servers. That happened to Zynga, that was paying $63M annually to Amazon and decided to step back from Amazon to their own Data Centers again. (another fortune tech link)

The limited CPU power was also a deal breaker for many companies that needed really powerful CPU and gigs of RAM for their Database Servers. Now this situation is much better with the introduction of the new Servers.

This developer can benefit from doing bacups with a click, cloning, starting instances from an image, having more static ip’s with a click, deploying built-in (from the Cloud provider) load balancers, using monitoring services like CloudWatch, creating Volumes and attaching to the servers for additional space…

Example B) An Startup with fluctuating number of users and hopes of growing

Imagine an Startup with a wonderful Facebook Application.

During 80% of the day has few visits, may be only need 3 Servers, but during 20% of the hours of the day from 10:00 to 15:00 users connect like hell, so they need 20 servers to attend this traffic and workload, and may be tomorrow needs 30 servers.

With the Cloud they pay for 3 servers 24 hours per day and for the other 17 servers only pay the hours they are on, that’s 5 hours per day. Doing that they save money and they have an unlimited * amount of power. (* There are limits for real, you have to specially request authorisation to run more than default max. servers for the zone, that is normally 20 instances for Amazon. Also it can happen theoretically that when you request new instances the Zone has no instances available).

So well, for an Startup growing, avoiding hiring 20 dedicated servers and instead running into the Cloud as many as they need, for just the time they need, Auto-Scaling up and down, and can use the servers NOW and pay the next month with Visa card, all of that can make a difference for a growing Startup.

If the servers chosen are not powerful enough that is solved with a click, changing instance type. So fast. A minute.

It’s only a matter of money.

Example C) e-Learning companies and online universities

e-Learning platforms also get benefits from the Auto-Scaling for the full occupation hours.

The built-in functionalities of the Cloud to clone instances is very useful to deploy new web servers, or new environments for students doing practices, in the case of teaching Information Technology subjects, where the users need to practice against a real server (Linux or windows).

Those servers can be created and destroyed, cloned from the main -ready to go- template. And also servers can be scheduled to stop at a certain hour and to start also, so saving the money from the hours not needed.

Example D) Digital agencies, sports and other events

When there is an Special event, like motorcycle running, when a Football Team scores, when there is an spot in tv announcing a product…

At those moments the traffic to the site can multiply, so more servers and more bandwidth have to be deployed instantly. That cannot be done with physical servers, hardware, but is very easy to provision instances from the Cloud.

Mass mailing email campaigns can also benefit from creating new Servers when needed.

Example E) Proximity and SEO

Cloud providers have Data Centres everywhere. If you want to have servers in Asia, or static content to be deployed faster, or in South-America, or in Europe… the Cloud providers have plenty of Data Centers all over the world.

Example F) Game aficionado and friends sharing contents

People that loves cooperative games can find the needed hungry bandwidth and at a moderate price. If they run their private server few hours, at night, from 22:00 to 01:00 as example, they will benefit from a great bandwidth from the big Cloud provider and pay only 3 hours per day (the exceed of traffic uses to be paid in most providers, but price of additional GB uses to be really really competitive).

Friends sharing contents in an Ftp also, can benefit from this Cloud servers, but probably they will find more easy to use services like Dropbox.

Example G) Startup serving contents

An Startup serving videos, images, or books, can benefit not only from the great bandwidth of big Cloud providers (this has been covered before), but for a very cheap price for exceeding Gigabyte transferred.

Local ISP can’t offer 150 Mbit for an instance of USD $20 and USD $0.12 per additional GB transferred.

Many Cloud providers also allow unlimited incoming traffic from the Internet, and from Server to Server through private ip’s.

Other cases

For other cases Dedicated Servers are much more Powerful, faster and cheaper, at the price of being “static” in the sense of attached, not layer abstracted, but all the aspects of your Project have to be taken in count before deciding stepping into or out of the Cloud.

In general terms I would say that the Cloud is for Scaling.

NAS and Gigabit

I’ve found this problem in several companies, and I’ve had to show their error and convince experienced SysAdmins, CTOs and CEO about the erroneous approach. Many of them made heavy investments in NAS, that they are really wasting, and offering very poor performance.

Normally the rack servers have their local disks, but for professional solutions, like virtual machines, blade servers, and hundreds of servers the local disk are not used.

NAS – Network Attached Storage- Servers are used instead.

This NAS Servers, when are powerful (and expensive) offer very interesting features like hot backups, hot backups that do not slow the system (the most advanced), hot disk replacement, hot increase of total available space, the Enterprise solutions can replicate and copy data from different NAS in different countries, etc…

Smaller NAS are also used in configurations like Webservers’ Webfarms, were all the nodes has to have the same information replicated, and when a used uploads a new profile image, has to be available to all the webservers for example.

In this configurations servers save and retrieve the needed data from the NAS Servers, through LAN (Local Area Network).

The main error I have seen is that no one ever considers the pipe where all the data is travelling, so most configurations are simply Gigabit, and so are bottleneck.

dell-blade-servers-enclosureImagine a Dell blade server, like this in the image on the left.

This enclosure hosts 16 servers, hot plugable, with up to two CPU’s each blade, we also call those blade servers “pizza” (like we call before to rack servers).

A common use is to use those servers to have Vmware, OpenStack, Xen or other virtualization software, so the servers run instances of customers. In this scenario the virtual disks (the hard disk of the virtual machines) are stored in the NAS Server.

So if a customer shutdown his virtual server, and start it later, the physical server where its virtual machine is running will be another, but the data (the disk of the virtual server) is stored in the NAS and all the data is saved and retrieved from the NAS.

The enclosure is connected to the NAS through a Gigabit connection, as 10 Gigabit connections are still too expensive and not yet supported in many servers.

Once we have explained that, imagine, those 16 servers, each with 4 or 5 virtual machines, accessing to their disks through a Gigabit connection.

If only one of these 80 virtual machines is accessing to disk, the will be no problem, but if more than one is accessing the Gigabit connection, that’s a maximum of 125 MB (Megabytes) per second, will be shared among all the virtual machines.

So imagine, 70 virtual machines are accessing NAS to serve web pages, with not much traffic, OK, but the other 10 virtual machines are doing heavy data transmission: for example one is serving data through FTP server, the other is broadcasting video, the other is copying heavy log files, and so… Imagine that scenario.

The 125 MB per second is divided between the 80 servers, so those 10 servers using extensively the disk will monopolize the bandwidth, but even those 10 servers will have around 12,5 MB each, that is 100 Mbit each and is very slow.

Imagine one of the virtual machines broadcast video. To broadcast video, first it has to get it from the NAS (the chunks of data), so this node serving video will be able to serve different videos to few customers, as the network will not provide more than 12,5 MB under the circumstances provided.

This is a simplified scenario, as many other things has to be taken in count, like the SATA, SCSI and SAS disks do not provide sustained speeds, speed depends on locating the info, fragmentation, etc… also has to be considered that NAS use protocol iSCSI, a sort of SCSI commands sent through the Ethernet. And Tcp/Ip uses verifications in their protocol, and protocol headers. That is also an overhead. I’ve considered only traffic in one direction, so the servers downloading from the NAS, as assuming Gigabit full duplex, so Gigabit for sending and Gigabit for receiving.

So instead of 125 MB per second we have available around 100 MB per second with a Gigabit or even less.

Also the virtualization servers try to handle a bit better the disk access, by keeping a cache in memory, and not writing immediately to disk.

So you can’t do dd tests in virtual machines like you would do in any Linux with local disks, and if you do go for big files, like 10 GB with random data (not just 0, they have optimizations for that).

Let’s recalculate it now:

70 virtual machines using as low as 0.10 MB/second each, that’s 7 MB/second. That’s really optimist as most webservers running PHP read many big files for attending a simple request and webservers server a lot of big images.

10 virtual machines using extensively the NAS, so sharing 100 MB – 7 MB = 93 MB. That is 9.3 MB each.

So under these circumstances for a virtual machine trying to read from disk a file of 1 GB (1000 MB), this operation will take 107 seconds, so 1:47 minutes.

So with this considerations in mind, you can imagine that the performance of the virtual machines under those configurations are leaved to the luck. The luck that nobody else of the other guests in the servers are abusing the disk I/O.

I’ve explained you in a theoretical plan. Sadly reality is worst. A lot worst. Those 70 web virtual machines with webservers will be so slow that they will leave your company very disappointed, and the other 10 will not even be happier.

One of the principal problems of Amazon EC2 has been always disk performance. Few months ago they released IOPS, high performance disks, that are more expensive, but faster.

It has to be recognized that in Amazon they are always improving.

They have also connection between your servers at 10 Gbit/second.

Returning to the Blades and NAS, an easy improvement is to aggregate two Gigabits, so creating a connection of 2 Gbit. This helps a bit. Is not the solution, but helps.

Probably different physical servers with few virtual machines and a dedicated 1 Gbit connection (or 2 Gbit by 1+1 aggregated if possible) to the NAS, and using local disks as much as possible would be much better (harder to maintain at big scale, but much much better performance).

But if you provide infrastructure as a Service (IaS) go with 2 x 10 Gbit Fibre aggregated, so 20 Gigabit, or better aggregate 2 x 20 Gbit Fibre. It’s expensive, but crucial.

Now compare the 9.3 MB per second, or even the 125 MB theoretical of Gigabit of the average real sequential read of 50 MB/second that a SATA disk can offer when connected on local, or nearly the double for modern SAS 15.000 rpm disks… (writing is always slower)

… and the 550 MB/s for reading and 550 MB/s for writing that some SSD disks offer when connected locally. (I own two OSZ SSD disks that performs 550 MB).

I’ve seen also better configuration for local disks, like a good disk controller with Raid 5 and disks SSD. With my dd tests I got more than 900 MB per second for writing!.

So if you are going to spend 30.000 € in your NAS with SATA disks (really bad solution as SATA is domestic technology not aimed to work 24×7 and not even fast) or SAS disks, and 30.000 € more in your blade servers, think very well what you need and what configuration you will use. Contact experts, but real experts, not supposedly real experts.

Otherwise you’ll waste your money and your customers will have very very poor performance on these times where applications on the Internet demand more and more performance.

Why Cloud is not optional

data-center-companyIf you’re a Developer or an Entrepreneur to avoid Cloud is not an option.

It is a must to use the Cloud.

Why?.

Because if your project is a success, you’ll need to scale very fast from a single server to many, just to attend the increasing number of users.

And if you have a lot of users, you’ll need a lot of bandwidth.

Even if you have a single server, but want to serve video, will need a lot of bandwidth to serve data fast.

Here is where Cloud is not an option. It’s a must.

If you use a big server with a lot of RAM or CPUs, or several servers, Amazon EC2 is very expensive.

But to start with the needed power, and to be able to grow really fast, and to pay as you go there is no other option.

The smaller instance from Amazon, is able to serve 150 Mbit per second.

If you need to serve video, where would you be able to deliver it at 150 Mbit/sec rates at 17 € / 14.67 £ / US $23 per month?.

Nowhere else.

It’s not a matter of something fashion, there’s not alternative.

With the privative price of dedicated bandwidth in the data centres, no one else can offer something similar even for then times this price.

So if you need to be able to pass from a server to 20 or 100 with a click and within a minute, and you need to deliver contents very fast there is no other option.

With Amazon Cloud since you pay per hour, you can create 20 instances to face a rise of visitors, due to a campaign or because you have top visitors window of time, you can create instances as you need and destroy them when you don’t need them and pay only for the hours used.

So when your Start up is growing and low on money/resources, you save the costs of buying several physical server ($2,000 each), the time of installing, of replacing if a motherboard or disk crashes, and simply creating new instances in the Amazon Cloud as you need, and paying only for the time you use them.

So you can save the costs and grow as you need.

There are other benefits like you can use Amazon data centres in all-over the world, where the infrastructure is closer to your customers (reducing the latency and increasing the speed of servicing pages), the CDN service, load balancers…

The cost of the transferred Gigabyte is another reason.

One month I transferred 287 GB and paid only $50.

An small ISP can’t beat this nor even compete with this price and speed.