在Python中获取传入UDP数据包的TTL
我正在使用 Python 中的套接字模块进行一些基本的 UDP 客户端-服务器通信。我需要做的非常简单：客户端向服务器发送一个数据包，服务器用客户端的公共 IP 地址、端口和代表 UDP 数据包到达服务器时的 TTL 的数字进行应答。这是我的主要问题：有什么方法可以使用recvfrom() 等接收数据包，并读取它到达我的服务器时的 TTL 值吗？
非常感谢！
马泰奥·蒙蒂
I'm using the socket module in Python to do some basic UDP client-server communication. What I would need to do is quite simple: client sends server a packet, server answers with client's public ip address, port and a number representing the TTL the UDP packet had when it got to the server. This is my main problem: is there any way to recieve a packet with recvfrom() or so, and read the TTL value it had when it reached my server?
Thank you very much!
Matteo Monti
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我想你想setsockopt(IP_RECVTTL)然后使用recvmsg()。但是Python的标准库中似乎没有recvmsg（参见http://bugs.python.org/issue6560< /a>）。因此，您可能需要编写一个小型 C 或 C++ 共享库，该库可由 Python 导入并执行您想要的操作。或者尝试使用我链接的页面中的补丁。
I think you want to setsockopt(IP_RECVTTL) and then use recvmsg(). But Python doesn't seem to have recvmsg in its standard libraries (see http://bugs.python.org/issue6560). So probably you will need to write a small C or C++ shared library which is importable by Python and which does what you want. Or maybe try using the patches from page I linked.
Python 3.51 支持 IP_RECVTTL 或 IP_RECVTOS 等标志。我尝试了一下，它在 3.x Linux 内核中对我有用。
Python 3.51 has the support for flags such as IP_RECVTTL or IP_RECVTOS. I gave it a try and it worked for me in a 3.x linux kernel.
据我所知，这通常不会暴露给用户空间。我认为您必须使用 libpcap 之类的东西来完成此操作，如 Stack Overflow 答案中所述：
https://stackoverflow.com /a/2362554/864393
This isn't generally exposed to userspace, as far as I know. I think you'll have to use something like libpcap to accomplish this, as described in this Stack Overflow answer:
https://stackoverflow.com/a/2362554/864393