sntop: 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/sntop - from package: sntop

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

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