変更前
deb http://ftp.jaist.ac.jp/debian/ jessie main deb-src http://ftp.jaist.ac.jp/debian/ jessie main deb http://security.debian.org/ jessie/updates main deb-src http://security.debian.org/ jessie/updates main deb http://ftp.jaist.ac.jp/debian/ jessie-updates main deb-src http://ftp.jaist.ac.jp/debian/ jessie-updates main
変更後
deb http://archive.debian.org/debian jessie main deb-src http://archive.debian.org/debian jessie main deb http://archive.debian.org/debian-security jessie/updates main deb-src http://archive.debian.org/debian-security jessie/updates main
