sorted by: recent | see : popular

Content Tagged with to + linux

su is run a shell with substitute user and group IDs. su is used to become another user during a login session. Invoked without a username, su defaults to becoming the super user. The optional argument - may be used to provide an environment similar to what the user would expect had the user logged in directly.

Restricting su command to root superuser only is simple.

First, determining the path location of the binary is required using the following command

# which su

returns
~~~~~~~~~~~~~~~
/bin/su
~~~~~~~~~~~~~~~

Remember the current file mode bits and restrictions for su binary

# ls -la /bin/su

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-rwxr-xr-x 1 root root 24284 Apr 28 2007 /bin/su
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Noticed that su binary is world executable and world readable. This basically means anybody can call and execute the su binary and gain access to perhaps stolen password with bash-enabled user accounts. If you wish to change this, you can issue the following command as follows

# chmod 700 /bin/su

So, only root and root alone can call su binary command.

Note that, it is not advisable to do this if your su binary is set to suid root, that has similar attributes like below:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-rwsr-xr-x 1 root root 27052 2007-08-02 18:33 /bin/su
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

as it could affect some apps and package that links to suid root-ted su binary.

Ubuntu 7.04 is the current stable version of the Ubuntu operating system. The common name given to this release from the time of its early development was “Feisty Fawn”.

Before Upgrading You need to remember the following point

Take comple backup of your system before upgrading
Now you need to upgraded my Ubuntu Edgy Machine to Ubuntu Feisty.

We can Use Two methods to upgrade Ubuntu Edgy to Ubuntu Feisty

1) Using GUI

2) Using apt-get

Upgrading Ubuntu Edgy to Ubuntu Feisty

Method 1 - Using GUI

If you want to upgrade using GUI use the following command

gksu “update-manager -c ”

“-c” switch tells it to look for upgrades at all.

You should see the following screen here Now you can see 7.04 is available for upgrade click on upgrade

Now you should see the release notes as follows here you need to click on upgrade

Once you click on upgrade you might get the error “Authentication failed”

You need to fix the above error for this open the terminal and type the “gpg” and press enter once you see the following message

gpg:Go ahead and type your message …

Press Ctrl+C and then start the install process again.

Now you should see the following screen downloading upgrade tool

You need to enter root password and click ok

Preparing the upgrade in progress

You need to confirm the upgrade process by clicking “Start Upgrade”

Download in progress for all the required packages for Upgrade

Installation in progress

If you click on Terminal to see detailed installation in progress

Cleaning Up is in Progress

You need to restart the system to complete the Upgrade by clicking “Restart Now”

Method 2 - Using apt-get

Edit your /etc/apt/sources.list as root. Change every occurrence of edgy to feisty.

Use any prefered editor. If you have a CD-ROM line in your file, then remove it.

sudo vi /etc/apt/sources.list

or

use the following Simple command

sudo sed -e ’s/\edgy/ feisty/g’ -i /etc/apt/sources.list

Now you need to update the source list using the following command

sudo apt-get update

Upgrade using the following command

sudo apt-get dist-upgrade

Double check your process was finished properly using the following commd

sudo apt-get -f install

sudo dpkg --configure -a

Now you need to Reboot your machine to take your new ubuntu 7.04 installation to effect all changes.

Testing Your Upgrade

You can check the ubuntu version installed using the following command

sudo lsb_release -a

Output Looks like below

Distributor ID: Ubuntu
Description: Ubuntu feisty (development branch)
Release: 7.04
Codename: feisty

or

Just type the following command in your terminal

cat /etc/issue

Output Lokks like below

Ubuntu feisty (development branch) \n \l