innobackupex version 2.3.5 based on MySQL server 5.6.24 Linux (x86_64) (revision id: 45cda89)

apt-key adv --keyserver keys.gnupg.net --recv-keys 1C4CBDCDCD2EFD2A

sudo pico /etc/apt/sources.list

then add the following two lines
    deb http://repo.percona.com/apt jessie main
    deb-src http://repo.percona.com/apt jessie main

apt-get update

apt-get install percona-xtrabackup