polarssl_dh_client: 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/bin/polarssl_dh_client - from package: libpolarssl-runtime

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

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