On 27/12/2020 14:12, David Higton wrote:
> In message 
>            Chris Green  wrote:
>
>> Are there any simple 3G/4G add-ons for a Pi that will allow it to power up
>> into a mode where it has the ability to be connected to via the mobile data
>> connection?
>>
>> I want a system that I can connect to from my home desktop/laptop on
>> demand.
>>
>> Sort of 'thinking out loud' about this:-
>>
>>     I suppose a USB 3G/4G dongle could provide the hardware required
>>     to make a mobile connection to the PI, recommendations?
>>
>>     It has to 'connect on demand' dialling *to* the Pi, it can't keep
>>     the line open all the time, very expensive!
>>
>>     So, is there software for Linux (and thus for the Pi) which will
>>     handle incoming calls to allow ssh login?
>>
>>     How does one manage the other end?  Is there Linux desktop
>>     software to allow one to dial up a remote system and then squirt
>>     ssh down the connection?
>>
>> Any/all ideas would be very welcome.
>>
>> I'm happy with fairly low-level stuff, I am a retired software engineer,
>> grew up with Unix (solaris) command line and I'm also quite into home-build
>> electronics projects.
>
> It seems very much to me that this depends on whether the Pi can have
> a fixed IP address, or be behind a router that supports Dynamic DNS.
> If either of those is true, you can ssh to it easily.
>
> If you have no idea of its IP address, then it gets somewhat harder.

By definition on a mobile network its behind a HUGE NAT proxy. Unless
you are supremely lucky and you het an IPV6 address

>
> Tell us a bit more about the Pi's connectivity, and we may be able to
> help you more.
>
> David
>


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