xvpn: 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/xvpn - from package: alliance

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

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