VNC is considered to be an insecure protocol. The password is sent using fairly weak encryption, and the rest of the session is not encrypted at all. For that reason, when using VNC over an untrusted network or internet, I recommend you tunnel it over SSH.

To forward VNC port 5900 on localhost to remote host port 5900

ssh -L 5900:localhost:5900 vncserver

If your ssh server is listening on other port like: 222

ssh -L 5900:localhost:5900 vncserver -p 222

The same procedure can be done on a window$ machine using putty Read the rest of this entry »

tar is a compression utility that allows you to compress files and backup up your system.
Here are some useful tar commands to backup and restore files.
if you want to backup the content of /home and /etc:

tar cvpf /mnt/backup/tarball_bakup /home /etc

Once you have a full backup of your system you could do incremental backups using the –newer option, which backs up everything that has changed since the specified date

tar cvpf /mnt/backup/tarball_backup --newer 19Aug09 /home /etc

when things go wrong and you want to restore the content of backup

tar xvpf /mnt/backup/tarball_backup home/user

Sometimes you accidentally deleted a file; therefore, you only need to restore a single file. Remember when restoring from a tar archive, there’s no absolute path, in other words, tar removes all the leading slash “/” so /home/user/file1 becomes home/user/file1. And you should be in the / “root” directory.

tar xvpf /mnt/backup/tarball_backup home/user/shell1.sh

What about if you don’t know the exact name of the file but only part of the file name

tar tvpf /mnt/backup/tarball_backup | grep shell*

or

tar tvpf /mnt/backup/tarball_backup | more

to page trhough the backup file.

Here’s a good shell script  that performs monthly, weekly, and daily backus to a tgz file. Read the rest of this entry »

These steps apply to both Linksys wireless access points (WAPs) and Linksys DD-WRT wireless routers. Of course, DD-WRT wireless routers have additional security precautions that need to be taken on the router and wireless side.

1-Change the password – With all Linksys routers and access points, it is extremely important to change the device’s default password. Login to your router and enter the default password. The version of the firmware or the router that you are using will determine where the Change Password button is located. Make sure you find it. This is the single most important step. Change the default password and choose a password that contains both numbers and letters. This will reduce the possibility of your password being guessed or hacked.
2-Change your SSID – The SSID is the shared network name that all devices run on a wireless network. The name is case sensitive and should be no longer than 32 characters. You can use any keyboard character you choose when renaming the SSID. The default SSID of the Linksys access point or wireless broadband router is set to Linksys. It is highly recommended that you change the SSID to a unique name other than the default. Read the rest of this entry »

Your PC can get to data in RAM hundreds of times faster than it can fetch something from the Hard-Drive. If you are like me and have open at least 10 different application at the same time, plus playing around with 2 or 3 virtual machine, which, by the way, consume lots of memory space; also, all the usual application running in the background, your memory will run out pretty fast, and your PC will start to drag pretty soon. So Vista has a little tool called “ReadyBoost” that pretty much lets you use a USB Flash Drive as additional memory. Well, You might be wondering; what happens if someone pulls out the drive and tries to snoop out your data; well, don’t worry Vista encrypts the data on the Flash Drive. Read the rest of this entry »

Disk time percentage and disk queue length

IT professionals think of hard disk corruption or inadequate disk space as the cause of most system performance problems, but disk time is an equally important performance factor. Disk time is represented as a percentage of time that the hard disk is in use. If the hard disk is running 80 percent of the time, for example, you can be sure that system performance is suffering.

Another factor to consider is the average disk queue length, which refers to the number of processes that are waiting to use the hard disk. Using the disk time percentage in conjunction with the disk queue length will tell you not only how much the hard disk is being used but also if the heavy usage is a problem. For example, if the disk time is 40 percent but the average disk queue length has a factor of two or less, then the hard disk is keeping up with the demand that’s being placed on it. Read the rest of this entry »

Well after moving on to Vista, there are a few features of Windows XP that I miss. One of them is the Backup Utility of XP. Although Vista has its own backup utility, it has some disadvantages over xp NTbackup utility. Lets say you want to create a backup of just one folder containing images and docuements that you just finished working on. How would you do this in Vista? Well you can’t. Vista will not allow you to create backup of individual files, and here is where the flexibility of XP Backup Utility comes in handy. Another reasone is the fact that you can’t backup EFS protected files in Vista. So here is a step by step article on how to restore your NTbackup utility from XP to Vista. Read the rest of this entry »

I’ve been meaning to do a tutorial on cracking WPA wireless for quite a while, but I found this video that explains the methodology really simple. Let me say that cracking WPA is not like cracking WEP, in WEP you’re exploiting a vulnerability in the way the encryption algorithm is implemented, but in WPA the only vulnerability will be in the strength of the user passphrase. Yes you’ve guessed it, when cracking WPA basically what you’re doing is brute-forcing the user password, in other words the success of your attack will depend on your dictionary or password list. If the user’s passphrase is not in your dictionary, you will never crack the WPA key. There are several types of WPA dictionary list out there, but I highly recommend using rainbow-tables which can be several Gigs in size. How to find them?… Google is your friend! Read the rest of this entry »