Here is a way how to include Debian/Ubuntu ISO image into your /etc/apt/sources.list file. This kind of hack can prove handy in terms of reducing package download during the installation or if you do not have CD/DVD drive available ( or is broken ) on your system.

Let's assume that we have a Debian ISO image downloaded at the location: /mnt/storage/iSO/debian-i386-DVD-1.iso. As a first step we need to create a mount point to where this ISO image will be mounted to:

mkdir /mnt/debian-dvd

Now we need to add a /etc/fstab entry so the ISO image will be mounted every time we boot the system. Open up /etc/fstab and add a following line:

/mnt/storage/iSO/debian-i386-DVD-1.iso /mnt/debian-dvd/ udf,iso9660 loop 0 0

Once done we can include this local repository into /etc/apt/sources.list. Open up /etc/apt/sources.list file and add:

NOTE: change wheezy with your version.

deb file:/mnt/debian-dvd/ wheezy main contrib

All done. What remains is to mount the actual image:

# mount /mnt/debian-dvd/

and update apt's depository:

# apt-get update