Access your server from the outside world with a dynamic IP-addres

Posted in Debian, English tutorials, Latest news on March 8th, 2011 by yokke

Difference between a static and a dynamic IP

An IP address is used to communicate between computers. When a server has a static IP this will never change unless someone decides to. This IP is manually entered in the computer or server.An example of who uses a static IP is a web server. Every domain name has a web server, every public web server has an static IP.  For example www.google.com has the static IP  74.125.230.112 this IP will never change unless Google decides to move the web server to an other location. Because it isn’t possible to learn every IP-address on the internet we invented DNS (Domain Name System). How DNS works I’ll explain in one of my following tutorials for now just remember that DNS will resolve a domain name to the IP of the server.

What are the advantages and disadvantages of a static IP distribution

Advantages:

  • You can learn the IP
  • You can host a web server

Disadvantages

  • You need to configure an IP on each computer
  • You need to remember which IP-addresses are already used in your network

What are the advantages and disadvantages of Dynamic IP distribution

90% of the computers use a dynamic IP. This IP is distributed by a DHCP server.

Advantages

  • You don’t have to configure an IP manually
  • You can use Dynamic Domain Named Services to find your computer

Disadvantages

  • You need an DHCP server
  • You need to configure reserved addresses for printers etc
  • You don’t now which IP belongs to which computer unless you use DNS

So how do I solve my problem when my ISP gives me a dynamic IP and I want to contact my personal server from the world wide web?

Well, I’m going to explain this for my own ISP (also the router settings, this can be different on your router).

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Easy backup method for a Linux server

Posted in Debian, English tutorials, Latest news on February 20th, 2011 by yokke

Do I need backup?

Off course you need to backup your data! If you don’t have backups, you don’t have data security!

Depending on the value of your data you will need to make more backups or keep them longer or whatever. You should always ask yourself the question what if I lose all my data? Which data is extremely important.

You can make a backup of various data, for example:

  • The operating system
  • The storage server (RAID 5 = NO BACKUP!)
  • Mail server
  • SQL server
  • Web server

When you lose a server or its data you should be able to restore your data in a few hours. You can’t make it to lose all your data. When you are working in a professional environment you will notice that there is a backup plan (if not create one!). This plan indicates how often backups should be made and where they are stored.

When you make a backup never save this on the same disk as the original disk. If you do this, in case of a disk failure you will lose all your data + all your backup data. Therefor its important to have a backup disk or a backup server.

Backup is very important but whats even more important is the restore procedure. In case of a failure you will rely on your backups and you need to restore everything.

You should test if your backups work, test if they still work after you restored them. At least once each year you should test if your backup & recovery plan is working. By testing it, you will be familiar with the procedure and its problems. You can also indicate the time it takes to be up & running again. (Your management will demand answers when things go wrong, be prepared!)

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Server network statistics

Posted in Debian, English tutorials, Latest news on February 15th, 2011 by yokke

When you build a network, over time this network will grow. This is why it’s important to keep statistics. So you can expand before you run out of space or bandwidth.

Under Linux there are a few ways to do this. One of them I’m going to explain today.

The program I’ve found on the internet doesn’t do anything more than monitor your network traffic. The program runs under every Linux distribution.

At the beginning of this tutorial I would like to say that this is just a basic tool. Later on I will provide a detailed tool that uses snmp to make statistics.

In this tutorial I’m going to demonstrate how you can install vnStat under Debian 6.0.

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Will Btrfs be the new filesystem?

Posted in Debian, Latest news on February 14th, 2011 by yokke

Will Btrfs be the new file system?

We all know that an operating system need a file system to provide access to the disks. So what is a file system? A file system (often also written as filesystem) is a method of storing and organizing computer files and the data they contain to make it easy to find and access them. The most known examples are:

  • FAT
  • FAT 32
  • NTFS
  • EXT
  • EXT2
  • EXT3
  • EXT4
  • ZFS (Oracle)

Btrfs (“B-tree file system,” pronounced “Butter F S”) is a GPL-licensed copy-on-write file system for Linux announced by Oracle in 2007. This filesystem is still under heavenly development and is NOT ready to be used in an production environment. Btrfs is licensed under the GPL and open for contribution from anyone. Btrfs can do raid0, raid1, raid10. When blocks are read in, checksums are verified and if there are any errors, Btrfs tries to read from an alternate copy.

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Debian 6.0

Posted in Debian, Latest news on February 7th, 2011 by yokke

Debian 6.0

Debian 6.0 is released! I could not wait to download this distribution and test it. With the release of this version Debian has also decided to release a new website. The previous website was 13 years old so it was time for an update.
In my opinion the new website is beautiful.

Debian 6.0 uses a complete free kernel. If you want to use the non-free software you will need to add the non-free archive
Debian 6.0 functionality,

  • KDE 4.4
  • Gnome 2.30
  • Xfce 4.6

The boot manager of Debian 6.0 is the grub 2.0. Due the use of grub 2.0 it is possible to make your entire system EXT4.

The new Debian profiles itself as stable for servers but also usable for netbooks due the decrease of the boot time. They decreased boot time with starting some scripts simultaneously. There is a new file system which is called BTRFS we will do some research and write a full report about it.

So keep checking our site, we expect this report to be ready in a few weeks.

Official site: http://www.debian.org

Official wiki of btrfs: https://btrfs.wiki.kernel.org/index.php/Main_Page

Linux softwarematige RAID installatie met MDADM

Posted in Debian, Dutch tutorials, Latest news on August 9th, 2010 by yokke

UPDATE

Deze tutorial is geschreven met een debian 5.0 installatie. Debian 6.0 werkt ongeveer het zelfde dus deze tutorial is nog steeds bruikbaar maar de screenshots komen misschien niet meer overeen zoals verwacht!

Wat is een RAID installatie?

Door gebruik te maken van RAID zorg je ervoor date de up-time van een server verhoogt tegelijkertijd staat de data ook veiliger. Er zijn verschillende vormen van RAID.

  1. RAID 0: De data word over 1 of meerdere schijven verdeeld, hierdoor gaat zowel de lees als de schrijf snelheid naar boven. Als een van de schijven faalt is alle data verloren. Maar de server kan hierdoor wel dubbel zo snel naar zijn schijven schrijven en lezen.
  2. RAID 1: De schijven zijn een duplicaat van elkaar. Deze vorm van RAID is zeer duur maar wel de veiligste. De schrijf snelheid gaat niet naar boven omdat elke schijf de data moet schrijven. De leessnelheid gaat echter wel naar boven.
  3. RAID 5: Deze vorm van RAID is zowel veilig als goedkoop. Je hebt er wel minstens 3 schijven voor nodig. Als een van de schijven faalt, kan aan de hand van de 2 overige schijven alle data terug gezet worden. Indien er 2 of meerdere schijven tegelijk falen is er geen hoop meer voor de data.

Waar gaat deze tutorial over?

In deze tutorial ga ik een server installeren met RAID 1, ook ga ik uitleggen hoe we de boot record zodanig kunnen aanpassen dat de servers gewoon kunnen herstarten zonder problemen zelfs indien er een van de 2 schijven zou crashen.

Wat hebben we nodig?

dit hangt er vanaf of je een live systeem hebt of niet. Als je een fysieke server hebt, hebben we gewoon 2 harde schijven nodig in deze server. Anders gaan we gebruik maken van een virtuele machine. Dit kan je doen door gebruik te maken van bijvoorbeeld virtualbox

Het installeren van de Debian server in RAID 1

Zoals eerder uitgelegd is RAID 1 de veiligste oplossing voor belangrijke data. De RAID zoals wij hem hier gaan installeren noemt een softwarematige RAID, doordat we geen RAID controller gebruiken maar dit wel met software MDADM gaan nabootsen. Let wel op, dit kan soms lang duren. Voor 1 TB moet je toch algauw rekenen op 24 uur, daardoor raad ik je aan om voor deze eerste installatie kleinere schijven te gebruiken of alleszins kleinere partities.

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