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doc: net: Update NAT options for Internet connectivity

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The host NAT options for QEMU/native_sim Internet connectivity
needs updating.

Signed-off-by: Jukka Rissanen <jukka.rissanen@nordicsemi.no>
This commit is contained in:
Jukka Rissanen 2024-02-26 13:32:43 +02:00 • committed by Fabio Baltieri
commit 4323bfe71c
1 changed files with 8 additions and 5 deletions
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13
doc/connectivity/networking/qemu_setup.rst
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@ -160,14 +160,17 @@ For applications using the "Settings" facility (with the config option
set the :kconfig:option:`CONFIG_NET_CONFIG_MY_IPV4_GW` option to the IP address
of the gateway. For apps not using the "Settings" facility, set up the
gateway by calling the :c:func:`net_if_ipv4_set_gw` at runtime.
For example: ``CONFIG_NET_CONFIG_MY_IPV4_GW="192.0.2.2"``
To access the internet from a custom application running in QEMU, NAT
(masquerading) should be set up for QEMU's source address. Assuming 192.0.2.1 is
used, the following command should be run as root:
(masquerading) should be set up for QEMU's source address. Assuming ``192.0.2.1`` is
used and the Zephyr network interface is ``zeth``, the following command should be run as root:
.. code-block:: console
iptables -t nat -A POSTROUTING -j MASQUERADE -s 192.0.2.1
iptables -t nat -A POSTROUTING -j MASQUERADE -s 192.0.2.1/24
iptables -I FORWARD 1 -i zeth -j ACCEPT
iptables -I FORWARD 1 -o zeth -m state --state RELATED,ESTABLISHED -j ACCEPT
Additionally, IPv4 forwarding should be enabled on the host, and you may need to
check that other firewall (iptables) rules don't interfere with masquerading.
@ -179,7 +182,7 @@ To enable IPv4 forwarding the following command should be run as root:
Some applications may also require a DNS server. A number of Zephyr-provided
samples assume by default that the DNS server is available on the host
(IP 192.0.2.2), which, in modern Linux distributions, usually runs at least
(IP ``192.0.2.2``), which, in modern Linux distributions, usually runs at least
a DNS proxy. When running with QEMU, it may be required to restart the host's
DNS, so it can serve requests on the newly created TAP interface. For example,
on Debian-based systems:
@ -189,7 +192,7 @@ on Debian-based systems:
service dnsmasq restart
An alternative to relying on the host's DNS server is to use one in the
network. For example, 8.8.8.8 is a publicly available DNS server. You can
network. For example, ``8.8.8.8`` is a publicly available DNS server. You can
configure it using :kconfig:option:`CONFIG_DNS_SERVER1` option.