Making a router with NAT from Windows XP without enabling ICS

I've always wanted to know how to enable routing and NAT on XP box without enabling ICS (Internet Connection Sharing). Today it's time to write some lines about it. Let's begin.
1. We should enable service "Routing and Remote Access"
2. Open registry editor and navigate to "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters" and set IPEnableRouter to "1"

Then, open a command prompt and type the following commands:
3. netsh routing ip nat install
4. netsh routing ip nat add interface "WAN Interface Name" full
5. netsh routing ip nat add interface "LAN Interface Name" private

I'm not sure whether computer has to be restarted after this setup, but the answer is probably "yes".
Anyway, if something doesn't agree to work - just restart the computer before panic :D

P.S. One more thing to add:  
To check configured interfaces type netsh routing ip nat show interface

Cloning Virtual Machine from snapshot in virtualbox

Today I've faced an interesting task to make a new virtual machine from a snapshot of existing one in virtual box. After a little research, I've found nice guide how to do it:

To clonehd the Current State of a disk:

• Open the Virtual Media Manager (Menu: File>Virtual Media Manager).
• Navigate to the hard disk you want to clone and fully expand the tree (use * key on numeric keypad).
• Find the {hexUUID}.vdi file that is attached to the VM you want to clone the Current State of.
• Click the filename to the right of the 'Location:' displayed at the bottom of the window.
• Ctrl+C / Copy to copy the text to the clipboard, which will be something like:
  (path){b6441469-5ccb-418c-8fdd-73c5e1a17314}.vdi
• Ctrl+V / Paste and extract the hexUUID value (removing the {} brackets) and run clonehd to clone it!
  

  C:> VBoxManage clonehd b6441469-5ccb-418c-8fdd-73c5e1a17314 CloneDisk.vdi

To clonehd a snapshot of a disk:

• Open the Virtual Media Manager (Menu: File>Virtual Media Manager).
• Navigate to the hard disk you want to clone and fully expand the tree (use * key on numeric keypad).
• Find the {hexUUID}.vdi file that is attached to the VM (and Snapshot) you want to clone.
• Click the filename to the right of the 'Location:' displayed at the bottom of the window.
• Ctrl+C / Copy to copy the text to the clipboard, which will be something like:
  (path){75bd6ab1-ce25-4b56-aa39-7826c9ebcc93}.vdi
• Ctrl+V / Paste and extract the hexUUID value (removing the {} brackets) and run clonehd to clone it!
  

  C:> VBoxManage clonehd 75bd6ab1-ce25-4b56-aa39-7826c9ebcc93 CloneDisk.vdi

There is no GUI at the moment, but it could be easily done in command line.

Swap in Ubuntu

Swap can a dedicated partition or just a file on your hard disk, mounted as a swap partition. I don't think, that anyone could have a problem marking partition as a swap, but creating swap as a file could be more interesting task to do.
Here is quotations from official Ubuntu documentation:
"

For Adding a 512 MB swap

• Creating a file for 512 MB size you want:

We will create a /mnt/512Mb.swap swap file.

sudo dd if=/dev/zero of=/mnt/512Mb.swap bs=1M count=512

Here count=512, means we want our file to contain 512 blocks of bs=1M, which means block size = 1 mebibyte (1 048 576 bytes). Be careful *not* to do this dd of=/mnt/512Mb.swap bs=1M seek=512 count=0 Though the file grows to 512Mb immediately, it will have holes that makes it unusable.

• Formatting that file to create a swapping device:

sudo mkswap /mnt/512Mb.swap

• Adding the swap to the running system:

sudo swapon /mnt/512Mb.swap

The additional swap is now available and can be seen by "cat /proc/meminfo"

• Making the change permanent:

Edit the /etc/fstab: 

gksudo gedit /etc/fstab

Add this line at the end of the file:

/mnt/512Mb.swap  none  swap  sw  0 0

Save. After the next reboot the swap will be used automatically.
Here we go! 

What is swappiness and how do I change it?

The swappiness parameter controls the tendency of the kernel to move processes out of physical memory and onto the swap disk. Because disks are much slower than RAM, this can lead to slower response times for system and applications if processes are too aggressively moved out of memory.

• swappiness can have a value of between 0 and 100
• swappiness=0 tells the kernel to avoid swapping processes out of physical memory for as long as possible
• swappiness=100 tells the kernel to aggressively swap processes out of physical memory and move them to swap cache

The default setting in Ubuntu is swappiness=60. Reducing the default value of swappiness will probably improve overall performance for a typical Ubuntu desktop installation. A value of swappiness=10 is recommended, but feel free to experiment. Note: Ubuntu server installations have different performance requirements to desktop systems, and the default value of 60 is likely more suitable.

To check the swappiness value

cat /proc/sys/vm/swappiness

To change the swappiness value A temporary change (lost on reboot) with a swappiness value of 10 can be made with

sudo sysctl vm.swappiness=10

To make a change permanent, edit the configuration file with your favorite editor:

gksudo gedit /etc/sysctl.conf

Search for vm.swappiness and change its value as desired. If vm.swappiness does not exist, add it to the end of the file like so:

vm.swappiness=10

Save the file and reboot.

We can check swap with the following commands:

• sudo fdisk -l

• cat /proc/swaps