docs: add some initial more advanced documentationHEADmaster

The primary point of this is to describe installation procedure but we
should also describe basic router usage with NixOS as that ain't
documented elsewhere.

1 files changed, 38 insertions, 0 deletions

diff --git a/docs/initial-access.adoc b/docs/initial-access.adoc
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+= Initial router access after installation
+
+This describes how to access the router right after the initial NixOS
+installation. The WAN port has to be connected to the existing network to receive
+IP address. This has to be the same network the machine you are planning on
+using for connecting to the board is connected to. You have to get this IP
+somehow. One option is to use https://docs.turris.cz/hw/serial/[serial
+connection] to get it by logging in and entering command `ip addr`. Another
+option is scanning the local network or if you have access you can just look for
+`NixTurris` system in DHCP logs.
+
+Once you have IP address you should be able to login over SSH. The SSH allows
+loging to root user with password `nixturris`.
+
+Make sure you setup your own access route to the device before you do the
+initial rebuild as this setup is set only for the tarball boot and is removed
+with first boot. Feel free to paste the following to your initial configuration
+so you would not lost this default setting initialy:
+
+----
+users = {
+   mutableUsers = false;
+   users.root.password = mkDefault "nixturris";
+};
+services.openssh = {
+   enable = true;
+   passwordAuthentication = true;
+   permitRootLogin = "yes";
+};
+----
+
+Make sure you change this as soon as possible as this is highly unsafe.
+
+Now you can follow to the first NixOS rebuild. There you have to decide if you
+prefer ./nixos-rebuild-remote.adoc[managing it remotely] or
+./nixos-rebuild-onsite.adoc[managing it directly on the router]. The remote way
+is more complex to setup but much faster in the long run while rebuild on the
+router can be pretty much done immediately.