Usage of ./vtun:
-k string
Encrypt key (default "6da62287-979a-4eb4-a5ab-8b3d89da134b")
-l string
Local tun interface IP/MASK like 172.16.0.1/24 (default "172.16.0.1/24")
-p int
UDP port (default 2001)
-r string
Remote server external IP like 172.16.0.2 (default "172.16.0.2")