filesnarf: 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/sbin/filesnarf - from package: dsniff

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

On Debian possible default full paths are:

/usr/sbin/filesnarf - from package: dsniff

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

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