Checking refusal of a network connection

Peter J. Holzer hjp-python at hjp.at
Sat Jun 1 14:30:11 EDT 2019


On 2019-06-01 20:22:39 +0200, Markus Elfring wrote:
> >> I would expect that the IPv4 address from such a connection attempt
> >> would be automatically converted to a IPv6 loopback address.
> >
> > You haven't said which OS you are using, but as far as I know this
> > expectation will be frustrated at least on Linux: There ::1 and
> > 127.0.0.1 are distinct addresses.
> 
> How does this view fit to information from the Linux programmer's manual?
> See also: command “man 7 ipv6”

Which specific information in that man page contradicts what what I
wrote?

If you think of 

| IPv4 connections can be handled with the v6 API by using the
| v4-mapped-on-v6 address type; thus a program needs to support only
| this API  type to  support  both  protocols.

please note that 127.0.0.1 mapped to IPv6 is ::7f00:1, not ::1. So you
still need to bind to two addresses.

        hp

-- 
   _  | Peter J. Holzer    | we build much bigger, better disasters now
|_|_) |                    | because we have much more sophisticated
| |   | hjp at hjp.at         | management tools.
__/   | http://www.hjp.at/ | -- Ross Anderson <https://www.edge.org/>
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