ssmpingd: 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/ssmpingd - from package: ssmping

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