Hi guys,

I've set up a Pi as a *deeply* embedded controller where no physical access to it can be obtained without a *vast* amount of hassle, effort and time. It's running a script I wrote under Rapsbian for which it needs internet access via a wireless card that's plugged into it. When the power is switched on, the Pi boots to a CLI prompt in run level 4 (I think it's 4; the level before startx command is normally given). By this time it's got its wireless connection and all should be well. The wireless is its *only* connection to the outside world apart from the power supply.

Question is: if something should go wrong in future, can I SSH into the Pi via its wireless card net connection and see what's going on from a remote PC? And can I still get access if its wireless is up and running but it has no net connection - if I'm within a few feet of course?

Disclaimer: I know *nothing* about SSH so if this question is badly put, then I plead ignorance (as usual) .

Yes, but you should know the IP assigned to your wireless card. Some ISPs do not assign the same IP allways.

If the wireless card isn't connected to the Internet, you would not be able to access the pi via SSH. If this happens you could try connecting the Ethernet port & SSH into the pi.

Wireless card IP. Is that the same thing as its MAC address?
As for connecting to the ethernet port, that's impossible since wireless is the only means of I/O with this application.

Can you still access the Pi directly? If so login and type

You will get something like

Look at the area labelled wlan0 and the HWaddr is your MAC address (I have just set mine to all "ff", yours will look different). I have set up this Pi to have a static IP address of 192.168.1.92 (choose an address outside of your DHCP range) so everytime the Pi boots it will get this address. I had problems with setting a static IP add via the Pi so I allocated the IP address to the MAC address via my wifi router. Then:

and you are in.

HTH. I note you are assuming no net access but I am assuming a router is involved somewhere?

Cheers

1 members found this post helpful.

Thank you, Tim. Yes, wireless router a few feet away. I think I'll do the same as you and change it to all 'f's whilst I still have access to the pi and before I seal it away to its doom as a blind, deaf and dumb, permanently embedded device....

I would be more concerned with: what if someone unplugs the router ?

also, obviously you will need to do port forwarding on your router to pass thru port 22 traffic.

No worries on the router; I'm the only one with access to it. No idea what your other remark means but I guess I can search for port 22 traffic on the net. It's not a port number I'm familiar with, TBH.

Port 22 is the port SSH listens on. For a computer outside your lan to be able to SSH into the pi, your router would need to forward port 22 requests to the pi's local IP address.

Ok, getting the picture a bit better now. Well, all that matters at this stage is that (from the above comments) the walled-up Pi will still be accessible via wireless provided I know the IP of the pi's wireless card and use port 22 of my router to connect to it.
I can worry about the finer details if the setup ever goes wrong in future. The important thing is I have the peace of mind in knowing I won't have to break through brick walls to get physical access to the Pi for debugging purposes.

Have you tested the wireless signal strength to be sure it will work once bricked up?

Yes, it was one of the very first things I checked, thanks.

Wooahhh, maybe I phrased my response wrongly. In my post I changed the MAC address display to ff's to obscure my real MAC address. On the router you tie up a user defined static IP address to the MAC address you see in ifconfig.

I think you are on the right track though - you know your IP address and should be ready to go.

1 members found this post helpful.