ndisasm: 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 CentOS possible default full paths are:

/usr/bin/ndisasm - from package: nasm

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/ndisasm - from package: nasm

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

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