Network IP address assignments

[Richard]

Hi! I'm having difficulty understanding and modifying the BBBW network configuration.

At boot on the BBBW, somehow, these IP addresses are assigned

  SoftAP0: 192.168.8.1

  lo: 127.0.0.1

  usb0: 192.168.7.2

  usb1: 192.168.6.2

  wlan0: 192.168.1.xxx

But I can't figure out where each of these addresses comes from, nor -- more interestingly -- how to change them. If there is a single place where this happens, I've not found it. And if there is any documentation, I've not found it, either. [There's lots of documentation about debian network configuration on the Internet. Pick your favorite, but it may or may not apply to the BBBW. In fact, it probably doesn't.]

I do know how to use connmanctl (to set wlan0), but it explicitly ignores SoftAP0,  usb0, and  usb1 because of the line

  NetworkInterfaceBlacklist=SoftAp0,usb0,usb1

in /etc/connman/main.conf

So my questions are:

(a)  How and where is each of these assigned?

(b)  If I want to change one of them permanently, what do I do?

and while asking these questions, here's a related one:

(c)  How can I change the name and password for the BeagleBone-XXXX access point that goes with SoftAP0?

These questions arose from my concern about having two BBBWs on the same computer or even just the same LAN: how do I make sure that they don't use the same IP address?

Version info:

    Debian 9.6 stretch

    Linux beaglebone 4.14.67-ti-r73 #1 SMP PREEMPT Thu Aug 30 00:08:52 UTC 2018 armv7l GNU/Linux

    BeagleBoard.org Debian Image 2018-08-30

Many thanks,

Richard

[Mike Brandon]

In my limited experience, I ran into a lot of issues trying to modify the network settings as you are running into. I believe that the network settings are being controlled by conman. So I added to /etc/connman/main.conf the following:

NetworkInterfaceBlacklist=SoftAp0,usb0,usb1,{0},can0,can1

Then I was able to control network settings as expected in /etc/network/interfaces....although I did end up installing dhcpcd and am now utilizing that to control my network although I don't think I have worked out all of the kinks. BTW I am running Debian 8.7 IoT image.

Mike

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[Mike Brandon]

Sorry, copied and pasted from my application code that is driving the network configuration...the {0} in NetworkInterfaceBlackist is eth0

Mike

[Robert Nelson]

On Wed, Dec 5, 2018 at 2:38 PM Richard <rlte...@gmail.com> wrote:
>
> Hi! I'm having difficulty understanding and modifying the BBBW network configuration.
>
> At boot on the BBBW, somehow, these IP addresses are assigned
> SoftAP0: 192.168.8.1

/etc/default/bb-wl18xx (changeable)

> lo: 127.0.0.1
> usb0: 192.168.7.2

/etc/network/interfaces, mostly hard-coded now..

> usb1: 192.168.6.2

hard-coded... /opt/scripts/boot/am335x_evm.sh

> wlan0: 192.168.1.xxx
>
> But I can't figure out where each of these addresses comes from, nor -- more interestingly -- how to change them. If there is a single place where this happens, I've not found it. And if there is any documentation, I've not found it, either. [There's lots of documentation about debian network configuration on the Internet. Pick your favorite, but it may or may not apply to the BBBW. In fact, it probably doesn't.]
>
> I do know how to use connmanctl (to set wlan0), but it explicitly ignores SoftAP0, usb0, and usb1 because of the line
> NetworkInterfaceBlacklist=SoftAp0,usb0,usb1
> in /etc/connman/main.conf
>
> So my questions are:
> (a) How and where is each of these assigned?
> (b) If I want to change one of them permanently, what do I do?
> and while asking these questions, here's a related one:
> (c) How can I change the name and password for the BeagleBone-XXXX access point that goes with SoftAP0?

/etc/default/bb-wl18xx

Regards,

--
Robert Nelson
https://rcn-ee.com/

[Richard]

Many many thanks.

~Richard

[Chris Green]

Richard <rlte...@gmail.com> wrote:
> [-- multipart/alternative, encoding 7bit, 107 lines --]
>
> [-- text/plain, encoding 7bit, charset: UTF-8, 50 lines --]

>
> Hi! I'm having difficulty understanding and modifying the BBBW network
> configuration.
>
> At boot on the BBBW, somehow, these IP addresses are assigned
> SoftAP0: 192.168.8.1
> lo: 127.0.0.1

This is the 'loopback' address and is basically hard-coded and is the
same on all systems (though it can be anything in the 127.0.x.x
range). It's the address of the (BBB) system itself. Don't try and
modify it, it's fundamental to the way IPV4 networks work.


> usb0: 192.168.7.2
> usb1: 192.168.6.2

These two addresses are (I think) assigned by the USB drivers in some
way, I'm not very familiar with this.


> wlan0: 192.168.1.xxx
>
This address is (almost always) set by the DHCP server on the LAN,
it's not set by the BBB at all. The DHCP server is probably a router
though it can be another computer on the LAN. The address given to
the BBB will usually be the same each time it's booted but it isn't
necessarily so. The range of addresses assigned by the DHCP server is
usually configurable in the router/DHCP server.


(N.B. I've summarised a lot and skipped over lots of details and bits
I'm not familiar with, don't take the above as a full description of
how it works. There are, for example, other ways the wlan0 address
might be set, I've just described the most likely one).

--
Chris Green
·