From LQWiki

To make an ISO from an existing CDROM is very easy. You can use the dd command:

  $ dd if=/dev/hdc of=/tmp/NameOfISOFile

/dev/hdc is the location of your CDROM drive (secondary master in IDE tree). You should change this if you have your CDROM drive in another location. Since /dev/cdrom is usually a symlink to the CDROM drive, it may be easier to use:

  $ dd if=/dev/cdrom of=/tmp/NameOfISOFile

The image of the CDROM is now in file specificied in of=

You could now mount it or burn it.