Installing Certbot on Debian 8

root@server:~# cat /etc/apt/sources.list

deb http://ftp.de.debian.org/debian/ jessie main
deb-src http://ftp.de.debian.org/debian/ jessie main

deb http://security.debian.org/ jessie/updates main
deb-src http://security.debian.org/ jessie/updates main

deb http://ftp.de.debian.org/debian/ jessie-updates main
deb-src http://ftp.de.debian.org/debian/ jessie-updates main

deb http://ftp.debian.org/debian jessie-backports main

Now updating apt

root@server:~# apt update
Hit http://security.debian.org jessie/updates InRelease
Ign http://ftp.de.debian.org jessie InRelease 
Hit http://ftp.debian.org jessie-backports InRelease 
Hit http://ftp.de.debian.org jessie-updates InRelease 
Hit http://ftp.de.debian.org jessie Release.gpg 
Hit http://ftp.de.debian.org jessie Release 
Hit http://security.debian.org jessie/updates/main Sources 
Hit http://security.debian.org jessie/updates/main amd64 Packages 
Get:1 http://ftp.debian.org jessie-backports/main amd64 Packages/DiffIndex [27.8 kB] 
Hit http://security.debian.org jessie/updates/main Translation-en 
Get:2 http://ftp.debian.org jessie-backports/main Translation-en/DiffIndex [27.8 kB] 
Hit http://ftp.de.debian.org jessie-updates/main Sources 
Get:3 http://ftp.de.debian.org jessie-updates/main amd64 Packages/DiffIndex [7,408 B]
Get:4 http://ftp.de.debian.org jessie-updates/main Translation-en/DiffIndex [2,704 B]
Hit http://ftp.de.debian.org jessie/main Sources
Hit http://ftp.de.debian.org jessie/main amd64 Packages
Hit http://ftp.de.debian.org jessie/main Translation-en
Hit http://ftp.de.debian.org jessie/main Translation-de
Fetched 65.7 kB in 2s (25.7 kB/s) 
Reading package lists... Done
Building dependency tree 
Reading state information... Done
All packages are up to date.

Now installing from backports

root@server:~# sudo apt-get install certbot -t jessie-backports -f

Reading package lists... Done
Building dependency tree 
Reading state information... Done