wissam@wissam-laptop:~$ dpkg -l | grep linux-headers
ii  linux-headers-2.6.20-15                    2.6.20-15.27                           Header files related to Linux kernel version
ii  linux-headers-2.6.20-15-generic            2.6.20-15.27                           Linux kernel headers for version 2.6.20 on x
ii  linux-headers-generic                      2.6.20.15.14                           Generic Linux kernel headers