shorewall: 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:

/sbin/shorewall - from package: shorewall

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

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