kill_ctnnetwork: 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/kill_ctnnetwork - from package: ctn

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

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