PIN the kernel to the current version in apt

create a new file under /etc/apt/preferences.d with the following content

Package: linux-server
Pin: version 3.2.0.23.25
Pin-Priority: 1001

Package: linux-image-server
Pin: version 3.2.0.23.25
Pin-Priority: 1001

Package: linux-headers-server
Pin: version 3.2.0.23.25
Pin-Priority: 1001

then run

apt-get update
apt-get dist-upgrade

you will find that you won’t get the kernel upgrade notice any more.

you can find you current kernel version with

dpkg -l|grep linux

reference: http://linux.die.net/man/5/apt_preferences