move channel docs into git

docs/software/TODO.md

@@ -4,7 +4,7 @@ You probably don't care about this section - skip to the next one.
 
 ## before next release
 
-* changing channels requires a reboot to take effect https://github.com/meshtastic/Meshtastic-device/issues/752 
+* TEST THIS! changing channels requires a reboot to take effect https://github.com/meshtastic/Meshtastic-device/issues/752 
 * add UI in android app to reset to defaults https://github.com/meshtastic/Meshtastic-Android/issues/263 
 * bug report with remote info request timing out
 * firmware OTA updates of is_router true nodes fails?

docs/software/channels.md

@@ -0,0 +1,17 @@
+# Multiple channel support
+
+Version 1.2 of the software adds support for "multiple (simultaneous) channels".  The idea behind this feature is that a mesh can allow multiple users/groups to be share common mesh infrastructure.  Even including routing messages for others when no one except that subgroup of users has the encryption keys for their private channel.
+
+### What is the PRIMARY channel
+
+The way this works is that each node keeps a list of channels it knows about.  One of those channels (normally the first 1) is labelled as the "PRIMARY" channel.  The primary channel is the **only** channel that is used to set radio parameters.  i.e. this channel controls things like spread factor, coding rate, bandwidth etc... Indirectly this channel also is used to select the specific frequency that all members of this mesh are talking over.
+
+This channel may or may not have a PSK (encryption).  If you are providing mesh to 'the public' we recommend that you always leave this channel with its default psk.  The default PSK is technically encrypted (and random users sniffing the ether would have to use meshtastic to decode it), but the key is included in the github source code and you should assume any 'attacker' would have it.  But for a 'public' mesh you want this, because it allows anyone using meshtastic in your area to send packets through 'your' mesh.
+
+Note: Older meshtastic applications that don't yet understand multi-channel support will only show the user this channel.  
+
+### How to use SECONDARY channels
+
+Any channel you add after that PRIMARY channel is SECONDARY.  Secondary channels are used only for encyryption and (in the case of some special applications) security.  If you would like to have a private channel over a more public mesh, you probably want to create a SECONDARY channel.  When sharing that URL with your private group you will share the "Complete URL".  The complete URL includes your secondary channel (for encryption) and the primary channel (to provide radio/mesh access).
+
+Secondary channels **must** have a PSK (encryption).

docs/software/remote-admin.md

@@ -0,0 +1,121 @@
+# Remote node administration
+
+This is the first documentation for how to use the [multiple channels](channels.md) feature to enable remote adminstration of meshtastic nodes.  i.e. let you talk through the mesh to some far away node and change that nodes settings.  This is an advanced feature that (currently) few users would need.  Also, keep in mind it is possible (if you are not careful) to assign settings to that remote node that cause it to completely drop off of your mesh.
+
+Btw: I promised to document how multi-channel is now used to secure remote GPIO/serial access.  But probably best to debug these instructions first, so I'll wait on that.  If you **do** need to use remote GPIO/serial now, just follow these instructions but name your new channel "gpio" or "serial".
+
+## Creating the "admin" channel
+
+Okay - now that we've summarized what multiple-channel support is, we can move on to using it to provide remote administrative access to a node.
+
+By default, nodes will **only** respond to adminstrative commands via the local USB/bluetooth/TCP interface.  This provides basic security to prevent unauthorized access.  This is actually how 'normal' administration and settings changes work.  The only difference for the remote case is that we are sending those commands over the mesh.
+
+Before a node will allow remote admin access, it must find a channel 
+```
+meshtastic --info
+Connected to radio
+...
+Channels:
+  PRIMARY psk=default { "modemConfig": "Bw125Cr48Sf4096", "psk": "AQ==" }
+
+Primary channel URL: https://www.meshtastic.org/d/#CgUYAyIBAQ
+```
+
+So from this output you see that this node knows about only one channel and that its PSK is set to the default value.
+
+But if you then add an admin channel (with "meshtastic --ch-add admin").  Note: the name is important it must be "admin" (sorry):
+
+Your channels will now look like this:
+```
+meshtastic --ch-add admin
+Connected to radio
+Writing modified channels to device
+
+meshtastic --info
+Connected to radio
+...
+Channels:
+  PRIMARY psk=default { "modemConfig": "Bw125Cr48Sf4096", "psk": "AQ==" }
+  SECONDARY psk=secret { "psk": "HW7E3nMbiNbvr6MhsDonLCmj7eSAhttzjbIx/r5OQmg=", "name": "admin" }
+
+Primary channel URL: https://www.meshtastic.org/d/#CgUYAyIBAQ
+Complete URL (includes all channels): https://www.meshtastic.org/d/#CgUYAyIBAQopIiAdbsTecxuI1u-voyGwOicsKaPt5ICG23ONsjH-vk5CaCoFYWRtaW4
+```
+
+Notice that now we have a new secondary channel.  Also, the "--info" option prints out TWO URLs.  The "complete URL" includes all of the channels this node understands.  You should consider this URL something you should be very cautious about sharing.  In the case of remote adminstration, you only need the node you want to adminster and the node you are locally connected to know this new "admin" channel.
+
+## Sharing the admin channel with other nodes
+
+I'm going to assume you've already created the admin channel on your "local node" i.e. the meshtastic node sitting on your desk at your home.  But now you want to enable access on the "remote node" you want to eventually have far away from you.
+
+For this step you need physical access to both the nodes.
+
+1. Create the "admin" channel on the "local node" using the instructions above.
+2. Copy the "Complete URL" someplace for permanent reference/access.
+3. Connect meshtastic-python to the "remote node" over the USB port.
+4. For the "remote node" type "meshtastic --seturl the-url-from-step-2".
+5. Run "meshtastic --info" and confirm that the "Complete URL" is the same for both of the nodes.
+6. Done!
+
+At this point you can take your remote node and install it far away and still be able to change any of its settings.
+
+## Remotely administering your node
+
+Now that both your local node and the remote node contain your secret admin channel key, you can do things like this:
+
+Get the node list from the local node.
+
+```
+meshtastic --nodes
+Connected to radio
+/----------------------------------------------------------------------------------------------------------\
+|N|    User    |AKA|   ID    |        Position        |Battery|   SNR   |     LastHeard     |    Since     |
+|-+------------+---+---------+------------------------+-------+---------+-------------------+--------------|
+|1|Unknown 9058|?58|!28979058|25.0382°, 121.5731°, N/A|  N/A  |-13.50 dB|2021-03-22 09:25:42|19 seconds ago|
+\----------------------------------------------------------------------------------------------------------/
+```
+
+Using the node ID from that list, send a message through the mesh telling that node to change its owner name.
+
+```
+meshtastic --dest \!28979058 --set-owner "Im Remote"
+Connected to radio
+Setting device owner to Im Remote
+INFO:root:Requesting configuration from remote node (this could take a while)
+```
+
+And you can now confirm via the local node that the remote node has changed:
+
+```
+meshtastic --nodes 
+Connected to radio
+/----------------------------------------------------------------------------------------------------\
+|N|  User   |AKA|   ID    |        Position        |Battery|  SNR  |     LastHeard     |    Since    |
+|-+---------+---+---------+------------------------+-------+-------+-------------------+-------------|
+|1|Im Remote|IR |!28979058|25.0382°, 121.5731°, N/A|  N/A  |8.75 dB|2021-03-22 09:35:42|3 minutes ago|
+\----------------------------------------------------------------------------------------------------/
+```
+
+Note: you can change **any** parameter, add channels or get info from the remote node.  Here's an example of setting ls_secs and printing the complete device info from the remote node.
+
+```
+meshtastic --dest \!28979058 --set ls_secs 301 --info
+Connected to radio
+INFO:root:Requesting configuration from remote node (this could take a while)
+Set ls_secs to 301
+Writing modified preferences to device
+
+
+Preferences: { "lsSecs": 301, "region": "TW" }
+
+Channels:
+  PRIMARY psk=default { "modemConfig": "Bw125Cr48Sf4096", "psk": "AQ==" }
+  SECONDARY psk=secret { "psk": "HW7E3nMbiNbvr6MhsDonLCmj7eSAhttzjbIx/r5OQmg=", "name": "admin" }
+
+Primary channel URL: https://www.meshtastic.org/d/#CgUYAyIBAQ
+Complete URL (includes all channels): https://www.meshtastic.org/d/#CgUYAyIBAQopIiAdbsTecxuI1u-voyGwOicsKaPt5ICG23ONsjH-vk5CaCoFYWRtaW4
+```
+
+## Areas for future development
+
+In the future we will add a "deadman timer" to this feature so that the remote node will revert any changes if you fail to send a special "commit changes" command.  This will protect against sending bad settings to nodes that you can't physically access.  Instead if the node does not receive a commit message within 10 minutes it will revert all changes and (hopefully) rejoin the mesh.

docs/software/sw-design.md

@@ -6,5 +6,7 @@ This is a mini design doc for developing the meshtastic software.
 * Our [project board](https://github.com/orgs/meshtastic/projects/1) - shows what things we are currently working on and remaining work items for the current release.
 * [Power Management](power.md)
 * [Mesh algorithm](mesh-alg.md)
+* [Channels](channels.md) - documentation on how multiple simultaneous channels are used
+* [Remote adminstration](remote-admin.md)
 * [External client API](device-api.md) and porting guide for new clients (iOS, python, etc...)
 * TODO: how to port the device code to a new device.