fwb_ipfw: command not found

Have You tried accessing the binary with the full path?

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/fwb_ipfw - from package: fwbuilder

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