Thanks for your response,
I had been success running unixsim, and tested all of it's instructions.
Now my question is that if I can run my program go throgh default
ethernet
interface(like eth0) without passing tun/tap.
Or I can only communicate network interface by tun/tap.
Because I will port Lwip to a embedded system running uLinux.
Ahh, OK. This is not a simple task - you need to write or obtain
drivers for your hardware, then hook those into lwIP. This is more than
I can help you do as it would require detailed knowledge of what
hardware you're running. If you can tell use what hardware you're using
you may find there is someone on this list who can help though (and may
even have done the same thing).
Kieran