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Florian Westphal
878aed8db3
If destination port is above 32k and source port below 16k
assume this might cause 'port shadowing' where a 'new' inbound
connection matches an existing one, e.g.
inbound X:41234 -> Y:53 matches existing conntrack entry
Z:53 -> X:4123, where Z got natted to X.
In this case, new packet is natted to Z:53 which is likely
unwanted.
We avoid the rewrite for connections that originate from local host:
port-shadowing is only possible with forwarded connections.
Also adjust test case.
v3: no need to call tuple_force_port_remap if already in random mode (Phil)
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Phil Sutter <phil@nwl.cc>
Acked-by: Eric Garver <eric@garver.life>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.