hts: 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/hts - from package: httptunnel

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

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