ffconfig: 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 CentOS possible default full paths are:

/usr/bin/ffconfig - from package: fawkes-core

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