The Linux dialup WIFI server, part 1

My mother has a great cottage on a lake. There is no cell phone service for a few kilometers around. There is a landline. There is a form of rural data wireless that is often down. Thus the need for a dialup wifi server as a backup, for when rural data wireless service is unavailable. Too slow for web surfing, but enough for email and texting. This seems like a perfect task for Linux. After all, Linux is usually a good foundation for web servers, email servers, vpn servers, file share servers, voip servers, and more.

I started this project last year, and found that although Windows could drive the built-in 56K modem on a circa 2009 laptop, Linux could not. Fortunately, I have a US Robotics USB 56K modem, which is recognized by Linux.  I got as far as a dialup connection without DNS.

This year I learned how to override some settings in wvdial to enable dns. So i was able to surf on fedora 28 via dialup. However, I was unable to share the connection via the GUI networkmanager.

To explain why, let me tell you a few stories:

I should point out that sharing a connection like this is something that Windows can do without breaking a sweat. I first installed such a gateway, albeit dialup shared as a NAT over wired Ethernet, on a Windows 98 box in 1999.

Last year (2017), while on vacation at a hotel with a 2 device limit, I confronted the dilemma: how does one choose between a laptop, an iPad, and 2 cell phones? Answer: use a laptop with a second wifi adapter to provide a repeated hotspot under my control.

NetworkManager on Gnome 3 on Fedora offered to share a wired Ethernet connection as a local WIFI hotspot, but was unable to do other permutations — like a second wifi on usb sharing a first wifi connection to hotel wifi. Fortunately, the machine was able to dual-boot into Windows and share the  hotel wifi via a second wifi usb adapter.

Back to the Linux dialup wifi server project.

It would seem that I must configure hostapd, in order to create a hotspot that can share the dialup connection. I have followed the instructions, but have not succeeded so far — there are some things i can try. I find myself consulting blog posts from 2002-2011. I suppose that is the kind of deep time audience that reads these blog posts, a few at a time, in the future.

More to follow at the beginning of October when I return to the cottage to take another run at the problem. for now i will simulate the hostapd problem with a test machine here, then bring that solution to the cottage and test the integrated solution with the already-working dialup connection.

I suppose I could try to test the dialup connection via a voip analog telephone adapter device, but that seems wrong.

[edit 20180924] My brother had a somewhat similar but more successful experience in 2015:

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