Debian Jessie의 백포트에서 Certbot 설치

Debian Jessie에 Certbot을 설치하려고 할 때 다음을 따라야 합니다.certbot 설치 지침. 실패했습니다. 그럼 난 노력해데비안에 백보트 추가소스.목록문서. 또한 실패했습니다. 그렇다면 Jessie에 Certbot을 설치하는 방법은 무엇입니까? 백포트를 추가하는 방법도 알고 싶습니다.

내 시도는 다음과 같습니다.

root@deployer:~# apt-get install certbot
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package certbot
root@deployer:~# apt-get install certbot
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package certbot
root@deployer:~# 
root@deployer:~# cat /etc/*-release|grep VER
VERSION_ID="8"
VERSION="8 (jessie)"
root@deployer:~# echo deb http://ftp.debian.org/debian/dists/jessie-backports/ jessie-backports main > /etc/apt/sources.list
root@deployer:~# cat /etc/apt/sources.list
deb http://ftp.debian.org/debian/dists/jessie-backports/ jessie-backports main
root@deployer:~# apt-get update
Ign http://ftp.debian.org jessie-backports InRelease
Ign http://ftp.debian.org jessie-backports Release.gpg
Ign http://ftp.debian.org jessie-backports Release
Err http://ftp.debian.org jessie-backports/main amd64 Packages
  404  Not Found [IP: 130.89.148.12 80]
Ign http://ftp.debian.org jessie-backports/main Translation-en_US
Ign http://ftp.debian.org jessie-backports/main Translation-en
W: Failed to fetch http://ftp.debian.org/debian/dists/jessie-backports/dists/jessie-backports/main/binary-amd64/Packages  404  Not Found [IP: 130.89.148.12 80]

E: Some index files failed to download. They have been ignored, or old ones used instead.
root@deployer:~# apt-get install certbot
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package certbot
root@deployer:~#