linux system acting as access point/router?

[geoffrey mendelson]

I want to set up a laptop to act as a mifi type router. The reason is 
that I already have it, and it has a 6 hour battery.

What I want to do is normally use the Wifi as a connection to my home 
network, which already has routers, DSL lines, DHCP servers, etc. When 
the power is out, and they are all down, I want to start a network on 
the laptop and forward the internet connection from a USB cellular modem 
to various users here.

Sort of using a cell phone with wifi tethering, but instead using a laptop.

I was able to do it easily with Windows. Microsoft added it to Windows 7 
and someone wrote a GUI for it.

I would prefer to have the laptop running Linux.

An Ad Hoc network does not work, my Android devices do not see them.

I am running Zorin 7, which is an Ubuntu derivative.

Geoff.

-- 
Geoffrey S. Mendelson 4X1GM/N3OWJ
Jerusalem Israel.