How to install the sources for the 2.6.27-15-server kernel?

After an internet outage I had to reboot my asterisk server. (Ubuntu 9.04)
However my dahdi channels (1 FXO and 1 FXS) aren’t coming up.

root@medion:/usr/src/dahdi-linux-complete-2.2.0.2+2.2.0# dahdi_cfg
Notice: Configuration file is /etc/dahdi/system.conf
line 0: Unable to open master device '/dev/dahdi/ctl'
1 error(s) detected

So I decided to recompile dahdi:
[ul]
root@medion:/usr/src/dahdi-linux-complete-2.2.0.2+2.2.0# make all
make -C linux all
make[1]: Entering directory /usr/src/dahdi-linux-complete-2.2.0.2+2.2.0/linux' make -C drivers/dahdi/firmware firmware-loaders make[2]: Entering directory/usr/src/dahdi-linux-complete-2.2.0.2+2.2.0/linux/drivers/dahdi/firmware’
make[2]: Leaving directory /usr/src/dahdi-linux-complete-2.2.0.2+2.2.0/linux/drivers/dahdi/firmware' [b]You do not appear to have the sources for the 2.6.27-15-server kernel installed.[/b] <-------- :unamused: make[1]: *** [modules] Error 1 make[1]: Leaving directory/usr/src/dahdi-linux-complete-2.2.0.2+2.2.0/linux’
make: *** [all] Error 2
[/ul]

Q: How do I install the sources for the 2.6.27-15-server kernel :question:

In the mean time I found the answer: :smile:

sudo apt-get install linux-headers-$(uname -r)