socks5test: 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

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/socks5test - from package: dsbltesters

You may install the required package with command apt-get install {package}
Error in other languages:
socks5test: bevel nie gevind nie
socks5test: comandă negăsită
socks5test: comando não encontrado
socks5test: commande introuvable
socks5test: command not found
socks5test: käsku ei ole
socks5test: không tìm thấy lệnh
socks5test: komanda nerasta
socks5test: Kommando nicht gefunden.
socks5test: kommandot finns inte
socks5test: komut yok
socks5test: nie znaleziono polecenia
socks5test: níor aimsíodh an t-ordú
socks5test: no se encontró la orden
socks5test: no s'ha trobat l'ordre
socks5test: opdracht niet gevonden
socks5test: parancs nem található
socks5test: perintah tidak ditemukan
socks5test: príkaz nenájdený
socks5test: příkaz nenalezen
socks5test: команда не найдена
socks5test: командата не е открита
socks5test: 命令找不到
socks5test: コマンドが見つかりません