jftp: 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/jftp - from package: jftp

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