Why can't download flash plugin for Debian?

Environment:debian8+firefox esr 45.8 I want to install flash plugin for my firefox. Firefox doesn't know how to open this address, because one of the following protocols (apt) isn't associated with any program or is not allowed in this context. There is a material about apturl problem apturl for firefox Do as the webpage say. sudo apt-get install apturl E: Package 'apturl' has no installation candidate sudo aptitude search apturl get nothing And it is no use to set network.protocol-handler.app.apt in character chain with /usr/bin/apturl as value. How to install flash plugin is another problem which can be solved this way. 1.add proper source into sources.list echo "deb http://http.debian.net/debian/ jessie main contrib non-free" >> /etc/apt/sources.list 2.sudo aptitude search flash p browser-plugin-freshplayer-pepperflash - PPAPI-host NPAPI-plugin adapter for pepperflash p flashbake - automated snapshots with git p flashbench - identify flash storage properties v flashblock - p flashcache-dkms - write-back block device cache for Linux (DKMS version) p flashcache-utils - write-back block device cache for Linux (user space utilities) v flashgot - p flashplayer-chromium - Flash Player for Chromium (Pepper) p flashplayer-mozilla - Adobe Flash Player i flashplugin-nonfree - Adobe Flash Player - browser plugin p flashplugin-nonfree-extrasound - Adobe Flash Player platform support library for Esound and OSS 3. apt-get update 4. apt-get install flashplayer-mozilla The problem why **apt:adobe-flashplugin?channel=$distro-partner** can't be opened by firefox still remain.