iptables-xml: 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/iptables-xml - from package: iptables

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

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