filan: 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/bin/filan - from package: socat

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

On Debian possible default full paths are:

/usr/bin/filan - from package: socat

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

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