CentOS5.5中安装VirtualBOX增强工具

#sudo sh ./VBoxLinuxAdditions.run 

提示失败 

Building the VirtualBox Guest Additions kernel modules [FAILED] 
Your system does not seem to be set up to build kernel modules. 
Look at /var/log/vboxadd-install.log to find out what went wrong. 
Once you have corrected it, you can run /etc/init.d/vboxadd setup to build them. 

#gedit /var/log/vboxadd-install.log 内容 

Makefile:23: *** 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. 

安装GCC 

#yum install gcc 

# yum install gcc kernel-devel kernel-headers 

重启。 

再次安装VBoxLinuxAdditions，OK