Tested Result (Hetzner - Asiatech )

[sinaspooler]

Hi,
I'm writing this because I believe it may help you with the proof of concept.
I tested test_pkt.py and received packets using tcpdump. It worked with a white IP address from Hetzner.
However, when I tried it with a black IP address, it just didn't work! So what does that mean? You said there's no way for them to listen to every SYN packet—so how on earth are they blocking packets?!
MY TEST:

• ASIATECH - HETZNER
  Thanks for your effort, and please keep up the great work. The people of Iran and China deeply appreciate it.

[GFW-knocker]

فیلترینگ ایپی قاعدتا در شبکه زیرساخت باید اتفاق بیافته و نباید مربوط به isp باشه
اینکه چرا برا شما جواب نداده ممکنه مربوط به NAT یا مودم شما باشه
اگر هرجای مسیر دیوایسی باشه که از raw packet پشتیبانی نکنه اون packet دراپ میشه
آیا شما دقیقا فایل lite experiment رو اجرا کردید برای ارسال پکت؟
و آیا دقیقا پکت TCP AP فرستادید بدون SYN و در سرور دریافت نشد؟
یعنی با دسترسی root admin اجرا کردید و در wireshark چک کردید؟

[GFW-knocker]

@sinaspooler

You said there's no way for them to listen to every SYN packet

what i said is :
they can separate every SYN , check ip & drop them all.
but they cant check all packets other than SYN because frequency of them is much much higher.

actually if SYN=1 then packet is checked & dropped for sure
we send packet with SYN=0 ACK=1 PUSH=1