Thursday, December 17, 2009

Upgrade Fedora 7 to Fedora 8

Before upgrading your OS version we must take the backup of our system firstly. For upgrading to Fedora 8 from Fedora 7 follow the given below commands:

Update your packages:

yum update

Run following command to clear the yum cache:

yum clean all

Then run following command to install fedora 8 release packages:

rpm -Uvh

rpm -Uvh

Now this is the time to run upgrade over the machine:

yum upgrade

If it stops with an error like this one:
---> Package orca.i386 0: set to be updated
--> Finished Dependency Resolution

Error: Missing Dependency: gecko-libs = is needed by package yelp

simply uninstall the package that is causing the problem (in this case yelp) (I only had to do this with the yelp package which doesn't seem to be overly important)...

yum remove yelp

Ref. :

For upgrade from Fedora8 to Fedora 9, use below given release RPMs and other are same as above

rpm -Uhv

Upgrading from Fedora 9 to Fedora 10, follow below given URL:

Monday, December 7, 2009

Linux Security

----->   Enable Authentication for Single-User Mode

Single-User Mode is used for a system recovery. However, by default, no authentication is used if single-user mode is selected. This can be used to bypassing security on the server and gaining root access. To enable authentication for single-user mode, open the /etc/inittab, file:

# vi /etc/inittab

Add the following line to the file:



-----> Disable Interactive Hotkey Startup at Boot

A few Linux distribution like Fedora, CentOS or RHEL allows the console user to perform an interactive system startup by pressing [I] key. Using interactive boot, attacker can disable the firewall and other system services. Open /etc/sysconfig/init file:

# vi /etc/sysconfig/init

Modify the setting as follows:


-----> Setup Time-out for Login Shells

 Go into the user's home director:

# vi .bash_profile

readonly TMOUT
export TMOUT
In case of dealing with SSH, we need to define/enter the following:
To set an idle timeout interval, after this interval has passed, the idle user will be automatically logged out. Open /etc/ssh/sshd_config file, enter:

vi /etc/ssh/sshd_config

Find ClientAliveInterval and set to 300 (5 minutes) as follows:

ClientAliveInterval 300
ClientAliveCountMax 0

Save and close the file. Restart sshd:
# service sshd restart