i'm trying to install guest additions so that I can get full screen(Virtual box goes full screen but Guest OS stays centered)

I have an up to date kernel, development tools are installed. I got an error trying to install rpmforge(not sure if that's relevant).

I navigate to /media/VBOX... , run the file and get this error in my log file "unable to find the sources of your current kernel.

Specifiy KERN_DIR=<directory> and run make again.

not exactly sure how to do this. any help would be great.

PS I have latest edition of CentOS, I think its 6.3

Some additional questions:

Do you have the kernel headers installed on your computer? Did you ran the installation as root or via sudo?
What was the error you got trying to install rpmforge?

(some advice: first copy the guest additions to a directory on the guest before trying to install them.)

okay, sorry for long delay. I moved install files off "disc" and to a directory. still same error.

yum install kernel-devel kernel-headers tells me that I have the most up to date versions.

yum --enablerepo rpmforge install dkms tells me repository not found

all logged in as root.

Could you please check in: /etc/yum.repos.d/rpmforge.repo if rpmforge is present and enabled? (enabled=0 is off and enabled=1 is on).

extra info:
-----------
Virtualbox manual - Chapter 4 - Guest Additions
link:http://www.virtualbox.org/manual/ch04.html#idp12039536

rpmforge is enabled, the rpm extras was not, but i enabled it. dkms is now installed, and i've gotten a new error...

Uninstalling modules from DKMS
Attempting to install using DKMS

Creating symlink /var/lib/dkms/vboxguest/4.2.12/source ->
/usr/src/vboxguest-4.2.12

DKMS: add Completed.

Error! Your kernel headers for kernel 2.6.32-279.el6.x86_64 cannot be found at
/lib/modules/2.6.32-279.el6.x86_64/build or /lib/modules/2.6.32-279.el6.x86_64/source.
You can use the --kernelsourcedir option to tell DKMS where it's located.
Failed to install using DKMS, attempting to install without
/tmp/vbox.0/Makefile.include.header:97: *** Error: unable to find the sources of your current Linux kernel. Specify KERN_DIR=<directory> and run Make again. Stop.
Creating user for the Guest Additions.
Creating udev rule for the Guest Additions kernel module.

Sounds like you need the headers that match your installed kernel.

You can install it with this command: sudo yum install kernel-headers.

If that doesn't work we have to check what kernel is installed and go from there. To check you can use: uname -r in a terminal window.

Iceman81 did you solved the problem? Are things working now?
Hoping to hear from you.