ns3.17-bench-simulator: 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/ns3.17-bench-simulator - from package: ns3

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

Error in other languages:
ns3.17-bench-simulator: bevel nie gevind nie
ns3.17-bench-simulator: comandă negăsită
ns3.17-bench-simulator: comando não encontrado
ns3.17-bench-simulator: commande introuvable
ns3.17-bench-simulator: command not found
ns3.17-bench-simulator: käsku ei ole
ns3.17-bench-simulator: không tìm thấy lệnh
ns3.17-bench-simulator: komanda nerasta
ns3.17-bench-simulator: Kommando nicht gefunden.
ns3.17-bench-simulator: kommandot finns inte
ns3.17-bench-simulator: komut yok
ns3.17-bench-simulator: nie znaleziono polecenia
ns3.17-bench-simulator: níor aimsíodh an t-ordú
ns3.17-bench-simulator: no se encontró la orden
ns3.17-bench-simulator: no s'ha trobat l'ordre
ns3.17-bench-simulator: opdracht niet gevonden
ns3.17-bench-simulator: parancs nem található
ns3.17-bench-simulator: perintah tidak ditemukan
ns3.17-bench-simulator: príkaz nenájdený
ns3.17-bench-simulator: příkaz nenalezen
ns3.17-bench-simulator: команда не найдена
ns3.17-bench-simulator: командата не е открита
ns3.17-bench-simulator: 命令找不到
ns3.17-bench-simulator: コマンドが見つかりません