It’s not necessarily required for you to have internet to install softwares, but if you don’t have the dependencies of the software, internet is required for the software to download and install it. deb files are installed using the dpkg software. deb file from the server and installing it. While you click the 'Install' button on Ubuntu Software Center or on Synaptic Package Manger, what the system actually do is downloading the. With the file, you can install softwares on your system. Install Software With Dependencies Offlineĭebian Systems like Ubuntu and others’ software packages has the extension.