arptables: 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:

/sbin/arptables - from package: arptables_jf

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

On Debian possible default full paths are:

/sbin/arptables - from package: arptables

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

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