If you have Apache directories that you want only certain IP to be able to access.  Say you have a management interface that you only want employees to have access to.

Once you have properly put the fowling code into
/etc/apache2/sites-available/default

and you are not comming from one of the allowed IP you will be greated with a page that says.

Forbidden

You don’t have permission to access /directory/onwebserver/index.php on this server.

Otherwise the normal web page will show up.

<Directory /var/www/super/secret/>
order deny,allow
deny from all
allow from 10.10.0.100 192.168.77.44
</Directory>

In this example I will how you how to force dhcpd to bind to a individual interface, or multiple interfaces.  I am using Debian 5 in this example.

From /etc/init.d/dhcp3-server

You will notice this variable $INTERFACES is refrenced but never used anwhere else.  It is there for you to tell dhcpd which interface to listen on.  You can also add in multiple interfaces there, separated by a space.

INTERFACES=”eth1″

I just want to share this simple command to show you how to list out all installed packages on a system.  It is often useful when you need to compare two system, or easily check to see if you installed a package already.

dpkg –get-selections

server:/var/log/openvpn# dpkg –get-selections
acpi-support-base                               install
acpid                                           install
adduser                                         install
apache2                                         install
apache2-mpm-prefork                             install
apache2-utils                                   install
apache2.2-common                                install
apt                                             install
… and losts more

This also works on Debian like operating systems like Ubuntu.  Below is a example from my Debian desktop.

user@server:~$ dpkg –get-selections|grep xserver
x11-xserver-utils                               install
xserver-common                                  install
xserver-xorg                                    install
xserver-xorg-core                               install
xserver-xorg-input-all                          install
xserver-xorg-input-evdev                        install
xserver-xorg-input-mouse                        install
xserver-xorg-input-synaptics                    install
xserver-xorg-input-vmmouse                      install
xserver-xorg-input-wacom                        install
xserver-xorg-video-all                          install
xserver-xorg-video-apm                          install
xserver-xorg-video-ark                          install
xserver-xorg-video-ati                          install
xserver-xorg-video-chips                        install
xserver-xorg-video-cirrus                       install
xserver-xorg-video-fbdev                        install
xserver-xorg-video-geode                        install
xserver-xorg-video-i128                         install
xserver-xorg-video-i740                         install
xserver-xorg-video-intel                        install
xserver-xorg-video-mach64                       install
xserver-xorg-video-mga                          install
xserver-xorg-video-neomagic                     install
xserver-xorg-video-nv                           install
xserver-xorg-video-openchrome                   install
xserver-xorg-video-r128                         install
xserver-xorg-video-radeon                       install
xserver-xorg-video-rendition                    install
xserver-xorg-video-s3                           install
xserver-xorg-video-s3virge                      install
xserver-xorg-video-savage                       install
xserver-xorg-video-siliconmotion                install
xserver-xorg-video-sis                          install
xserver-xorg-video-sisusb                       install
xserver-xorg-video-tdfx                         install
xserver-xorg-video-trident                      install
xserver-xorg-video-tseng                        install
xserver-xorg-video-v4l                          install
xserver-xorg-video-vesa                         install
xserver-xorg-video-vmware                       install
xserver-xorg-video-voodoo                       install