NPtcp: 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/NPtcp - from package: netpipe-tcp

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

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