poff: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/poff - from package: ppp

You may install the required package with command apt-get install {package}

Error in other languages:
poff: bevel nie gevind nie
poff: comandă negăsită
poff: comando não encontrado
poff: commande introuvable
poff: command not found
poff: käsku ei ole
poff: không tìm thấy lệnh
poff: komanda nerasta
poff: Kommando nicht gefunden.
poff: kommandot finns inte
poff: komut yok
poff: nie znaleziono polecenia
poff: níor aimsíodh an t-ordú
poff: no se encontró la orden
poff: no s'ha trobat l'ordre
poff: opdracht niet gevonden
poff: parancs nem található
poff: perintah tidak ditemukan
poff: príkaz nenájdený
poff: příkaz nenalezen
poff: команда не найдена
poff: командата не е открита
poff: 命令找不到
poff: コマンドが見つかりません