Is there any way to make the installation of Debian unattended, I need to install on multiple machines with similar hardware.
Basically I need to install Debian system without human interaction, with predefined parameters such as users and passwords.
yes you can do that using Debian's "preseeding" system which is based on the deb-conf engine.
read here: https://www.debian.org/releases/wheezy/i386/apbs02.html.en
Basically you create a preseed file that the install system retrieves at boot time reading a series of parameters/variables that correspond to the inputs required by the Debian interactive install system (deb-conf). If the preseed file has a particular variable in it the corresponding interactive parameter request is just skipped taking the value from the pressed file. You can define "all" the install required parameters then you get a Debian fully unattended install.
You can go the route of FAI, "Fully Automated Installation" which is specifically designed for multiple repetitive installs. See the website for details.
Google for "Debian preseeding". It usually involves setting up a DHCP/DNS/TFTP/HTTP server combination, serving addresses, names, basic boot files and preseed files. You can skip all but the last with a bootable usb stick with mini iso but with a local preseed file.
