docs: networking: convert ip_dynaddr.txt to ReST

- add SPDX header;
- adjust title markup;
- mark code blocks and literals as such;
- adjust identation, whitespaces and blank lines;
- add to networking/index.rst.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 40 insertions, 0 deletions

diff --git a/Documentation/networking/ip_dynaddr.rst b/Documentation/networking/ip_dynaddr.rst
new file mode 100644
index 000000000000..eacc0c780c7f
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+++ b/Documentation/networking/ip_dynaddr.rst
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+.. SPDX-License-Identifier: GPL-2.0
+
+==================================
+IP dynamic address hack-port v0.03
+==================================
+
+This stuff allows diald ONESHOT connections to get established by
+dynamically changing packet source address (and socket's if local procs).
+It is implemented for TCP diald-box connections(1) and IP_MASQuerading(2).
+
+If enabled\ [#]_ and forwarding interface has changed:
+
+  1)  Socket (and packet) source address is rewritten ON RETRANSMISSIONS
+      while in SYN_SENT state (diald-box processes).
+  2)  Out-bounded MASQueraded source address changes ON OUTPUT (when
+      internal host does retransmission) until a packet from outside is
+      received by the tunnel.
+
+This is specially helpful for auto dialup links (diald), where the
+``actual`` outgoing address is unknown at the moment the link is
+going up. So, the *same* (local AND masqueraded) connections requests that
+bring the link up will be able to get established.
+
+.. [#] At boot, by default no address rewriting is attempted.
+
+  To enable::
+
+     # echo 1 > /proc/sys/net/ipv4/ip_dynaddr
+
+  To enable verbose mode::
+
+    # echo 2 > /proc/sys/net/ipv4/ip_dynaddr
+
+  To disable (default)::
+
+     # echo 0 > /proc/sys/net/ipv4/ip_dynaddr
+
+Enjoy!
+
+Juanjo  <jjciarla@raiz.uncu.edu.ar>