Run python http.server for IPv6 only
Question:
python3 -m http.server --bind :: launches a python web server, as shown in Python 3: Does http.server support ipv6?. However, it also supports IPv4, because I can visit the web server with localhost:8000 (edit: even 127.0.0.1:8000 works). I don’t want that. The python http.server is dual-stack even though I used --bind:
By default, server binds itself to all interfaces. The option -b/–bind specifies a specific address to which it should bind. docs
Is there a way to disable IPv4? I asked it to bind to ::.
Answers:
There is no way to do this because the support for IPv4 is not provided by Python, but by the OS. I’m not 100% sure though.
More details
The output of lsof -nP -i4TCP | grep LISTEN (open network files/sockets on IPv4) include (notice the IPv6)
Python 30838 ben 3u IPv6 0xb364e79e7fc44213 0t0 TCP *:8000 (LISTEN)
This is alongside the IPv6 network file lsof -nP -6 (warning: lsof -nP -i6TCP doesn’t show it ):
Python 30838 ben 3u IPv6 0xb364e79e7fc44213 0t0 TCP *:8000 (LISTEN)
I think the OS creates a network file/socket for IPv4 packets even though Python did not ask for it (for convenience). From my understanding of lsof and the docs:
When an open IPv4 network file’s address is mapped in an IPv6 address,
the open file’s type will be IPv6, not IPv4, and its display will be
selected by ‘6’, not ‘4’.
I’ve just realized this is a very similar "feature" to one I was reading yesterday…
This means it’s no longer a Stack Overflow answer but a Linux one: How do you turn off dual-stack networking for the server?
python3 -m http.server --bind :: launches a python web server, as shown in Python 3: Does http.server support ipv6?. However, it also supports IPv4, because I can visit the web server with localhost:8000 (edit: even 127.0.0.1:8000 works). I don’t want that. The python http.server is dual-stack even though I used --bind:
By default, server binds itself to all interfaces. The option -b/–bind specifies a specific address to which it should bind. docs
Is there a way to disable IPv4? I asked it to bind to ::.
There is no way to do this because the support for IPv4 is not provided by Python, but by the OS. I’m not 100% sure though.
More details
The output of lsof -nP -i4TCP | grep LISTEN (open network files/sockets on IPv4) include (notice the IPv6)
Python 30838 ben 3u IPv6 0xb364e79e7fc44213 0t0 TCP *:8000 (LISTEN)
This is alongside the IPv6 network file lsof -nP -6 (warning: lsof -nP -i6TCP doesn’t show it ):
Python 30838 ben 3u IPv6 0xb364e79e7fc44213 0t0 TCP *:8000 (LISTEN)
I think the OS creates a network file/socket for IPv4 packets even though Python did not ask for it (for convenience). From my understanding of lsof and the docs:
When an open IPv4 network file’s address is mapped in an IPv6 address,
the open file’s type will be IPv6, not IPv4, and its display will be
selected by ‘6’, not ‘4’.
I’ve just realized this is a very similar "feature" to one I was reading yesterday…
This means it’s no longer a Stack Overflow answer but a Linux one: How do you turn off dual-stack networking for the server?