tunnelx: 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/tunnelx - from package: tunnelx

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

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