aa797057

PID: SoupGate-Win32 v1.05
On Sun, 22 Jul 2018 00:04:30 +0200,
real-not-anti-spam-address@apple-juice.co.uk (D.M. Procida) declaimed the
following:

>
>And, if it loses a connection for whatever reason, it won't just sit
>there waiting for it to come back, but will actively and aggressively
>try to establish a new one - for example, if it loses its IP connection
>over Ethernet, it will keep asking for a new DHCP IP address until it
>gets one.
>
>Is this possible?
>

 Well... the Pi-Star software is apparently configured to spend 2
minutes trying to get a network connection before it creates a WiFi access
point (no Internet) for itself. I say "apparently" as I've not seen that
behavior -- only read about. The purpose being to let one access the
software configuration page wirelessly -- in order to provide the
connection information for an Internet WiFi connection.

 However, what you ask for is not a boot-time action.

 First step is to define loss of "IP connection". Especially since
Ethernet connections are via MAC addresses, IP addresses are embedded
inside packets that get routed to hardware MAC addresses. DHCP leases of IP
numbers are commonly for a 24 hour period so pulling an Ethernet cable,
say, does not result in loss of IP lease by the router -- only loss of data
packets being sent over the disconnected cable.

 The second part of that is determining where the break in connectivity
takes place. After all, you might have a valid DHCP lease and Ethernet
connection to the router -- but the router may not have connectivity to the
Internet.

 I suppose one could set up a cron job that periodically pings what is
supposed to be the next step, so is tied to a configuration (the router) --
but that does require knowing the IP address of the router (can't rely upon
domain name, since it may not be in a DNS system to be translated to IP# --
especially if the DNS is on the other side of the router). If you can't
ping the router via a particular interface (and setting up logic to ignore
one interface if another is up would be another complication) then you
could assume the interface is disconnected -- but there is no sense in
sending DHCP requests to a disconnected interface.

 With regards to WiFi -- considering how many devices automatically
connect (or attempt to) when one moves from the range of one access point
to another, it is obviously doable... But does require having either open
access points (no WPA password) or a list of connection parameters
(supplicant? file in Linux); and a means of determining loss of WiFi
connectivity.

>Thanks,
>
>Daniele


--
 Wulfraed                 Dennis Lee Bieber         AF6VN
 wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/

--- SoupGate-Win32 v1.05