dummy_server: 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/dummy_server - from package: ipkungfu

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

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