rand_gen: 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:

/usr/lib/srtp/bin/rand_gen - from package: srtp-utils

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

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