guessnet: 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/sbin/guessnet - from package: guessnet

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

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