Web hosting Category

Generate htpasswd style passwords without installing apache utilities

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This guide applies to most of the Linux operating systems with installed openssl utilities (installed usually by default).

From the command line enter the following command to generate a new user and add the password hash to file .htpasswd in the current directory:

printf “User1:$(openssl passwd -apr1 Passwd56374b)\n” >> .htpasswd

Where User1 is the username, Passwd56374b is the password you prefer. This is it.… Read the rest of this entry »

Disabling IPv6 on Debian, Ubuntu, Centos, Fedora and Redhat Linux

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I have no idea why I am posting how-to disable IPv6 on your Linux workstation or server – IPv6 is the only future, but here it goes:


Add /etc/sysctl.conf file with the following new lines and execute “sysctl -p” from ROOT shell:

net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1



Execute the following command from ROOT shell, then reboot the server:

echo net.ipv6.conf.all.disable_ipv6=1 > /etc/sysctl.d/disableipv6.conf


Centos, Fedora and Redhat Linux:

Add the following lines to /etc/sysctl.conf, then execute “sysctl -p” from ROOT shell:

net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1

Or … Read the rest of this entry »

Firewall open ports for NFS

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For better NFS security you should use firewall, however many folks experience a lot of problems if they are running NFS behind the firewall. Below, we have compiled the required ports (default) that you need to open in your firewall to let NFS traffic pass:

You can check out “listening” ports with rpcinfo -p command:

   program vers proto   port
100000    2   tcp    111  portmapper
100000    2   udp    111  portmapper
100024    1   udp  14758  status
100024    1   tcp  29024  status
100021    1   udp  55776  nlockmgr
100021    3   udp  55776  nlockmgr
100021    4   udp  55776  nlockmgr
100021    1   tcp  11796  nlockmgr

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MySQL Cluster 7.3 supports foreign keys

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Finally, MySQL Cluster 7.3 (not production version thought) supports foreign keys and that’s the feature many folks requested for years. With 7.3 you can drop and add foreign keys in real time – mysql cluster will deliver read/write requests online.

Check out Mysql labs and download MySQL Cluster 7.3 to test out new features and remember that MySQL Cluster 7.3 is not production stable version yet.… Read the rest of this entry »

Knot DNS server installation problem configure: error: liburcu not found

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I wanted to test out high-performance Knot DNS server and had problem while installing it on Centos 6.2 64-bit platform. The installation died with the error:

configure: error: liburcu not found

After some minutes of research, I found userspace urcu packages available for downloads at:


Debian and Ubuntu Linux distributions does have these packages in their repositories.… Read the rest of this entry »

set_real_ip_from and real_ip_header settings for Nginx

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A few weeks ago we got a customer with multiple remote proxy servers accelerating customer’s web site for caching and performance issues. As always, I use Nginx as a front end and forwarding all dynamic queries (PHP) to back-end Apache/PHP for processing. And we hit the wall with getting the real client IP and pass it to the back-end Apache so that all posts and comments do show real client IP address. Hey, site admin requires blocking spamming IP blocks as well as flooders!

Front end proxy servers were already set-up to send X-Forwarded-For header with real client IP address.… Read the rest of this entry »

Memcached replication for data redundancy

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A lot of high performance web sites use memcached to speed up caching and serve content much faster to the web visitors. By default memcached doesn’t offer any data redundancy and no replication feature – memcached uses server RAM to store all data and if the server hardware fails or it is rebooted all data that’s stored in the memcached daemon will be lost. In order to increase memcached data redundancy and offer high availability you should check out RepCached (Web site: http://repcached.lab.klab.org/ ) – it offers multi-master and asynchronous replication for 1.2.x memcached versions.

You can use Layer-4 load … Read the rest of this entry »

Increase vBulletin and WordPress MySQL speed by using fast SSD drives

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I’ve been consulting owners of very large blogs for a few years now and the last client was a very popular tech blog owner who’s web site has over 3.000.000 monthly visitors.

The server hardware specification:
4 CPU Intel E5640 (16 cores in total)

This WordPress powered blog runs on LAMP platform with Nginx (my favorite!) front-end server, Apache and MySQL on one physical server. The problem was IO load – the IO time wait as reported by “iostat” utility was sometimes over 26%. The average server load was over 8 all the time, while … Read the rest of this entry »

Why LAMP servers are the best

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LAMP stands for Linux, Apache, MySQL and PHP. Over at least 5 years I’ve been using LAMP and LNAMP (Linux, Nginx, Apache, MySQL and PHP) powered web servers to serve high bandwidth sites on simple commodity servers you can rent starting just from $30 per month.

My first choice of Linux server OS is Centos – a white hat clone from Redhat :) It’s free, easy to administer, fast to configure and not complex to keep up running. OS patches are also released fast and combined together with packet filters and other security software it does provide adequate security as … Read the rest of this entry »

100Mbps uplink for web hosting. How much traffic can I push?

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A few years ago a fully-dedicated 100Mbps up-link for a dedicated server was a dream for many folks. Not anymore! The bandwidth pricing went down drastically, the internet connectivity speed has increased a lot.

Nowadays even a budget dedicated server has 100 Mbps up-link and the question is how much bandwidth you can push?

Let’s look at the typical scenario: a web server hosting a large web site or blog. Since we are interested in maximum bandwidth your server can push using 100Mbps up-link, we will skip the server CPU/RAM/IO load issues that usually is a quite big problem with … Read the rest of this entry »