Basics Of Remote Cellular Access: Connecting Via VPN

January 14, 2021 by Lewin Day 9 Comments

You’ve got a machine hooked up to the Internet via a shiny new cellular modem, which you plan to administer remotely. You do a quick check on the external IP, and try and log in from another PC. Try as you might, SSH simply won’t connect. What gives?

The reality of the modern internet is that most clients no longer get their own unique IPv4 address. There simply aren’t enough to go around anymore. Instead, most telecommunications operators use Carrier Grade Network Address Translation which allows a single external address to be shared by many customers. This can get in the way of direct connection attempts from the outside world. Even if that’s not the case, most cellular operators tend to block inbound connections by default. However, there is a way around this quandary – using a VPN. Continue reading “Basics Of Remote Cellular Access: Connecting Via VPN” →

Modern Network Adapter For Retro Computers

October 14, 2020 by Bryan Cockfield 9 Comments

Universal Serial Bus, or USB, is so ingrained in modern computing that it’s hard to imagine a time without it. That time did exist, though, and it was a wild west of connector types, standards, and interfacing methods. One of the more interesting interfaces of the time was the SIO system found in 8-bit Atari computers which ended up sharing a lot of the features of modern USB, and its adaptability is displayed in this modern project which brings WiFi, Bluetooth, USB, and SD card slots to any old Atari with an SIO port.

The project is called FujiNet and it uses the lightweight protocol of SIO to add a number of modern features to the 8-bit machine. It’s based on an ESP32, and the chip performs the functions of a network adapter by bridging WiFi and Bluetooth to the Atari. It does this by simulating drives that would have potentially been used on the Atari in its time, such as a floppy disk drive, an RS232 interface, or a modem, and translating them to the modern wireless communication protocols. It even has the ability to emulate a printer by taking the output of the print job from the Atari and converting it to PDF within the device itself.

Not only does this bring a lot of functionality to the Atari, which you may be able to use to view sites like retro.hackaday.com, but the FujiNet is housed in a period-appropriate 3D-printed case that matches the look and feel of the original Atari. If you need a more generic solution for your retrocomputing networking adventures that isn’t limited to SIO, we recommend grabbing a Raspberry Pi to handle that.

Thanks to [Gavin] for the tip!

Hackaday Podcast 077: Secret Life Of SD Cards, Mining Minecraft’s Secret Seed, BadPower Is Bad, And Sailing A Sea Of Neon

July 24, 2020 by Mike Szczys 3 Comments

Hackaday editors Mike Szczys and Elliot Williams are deep in the hacks this week. What if making your own display matrix meant a microcontroller board for every pixel? That’s the gist of this incredible neon display. There’s a lot of dark art poured into the slivers of microSD cards and this week saw multiple hacks digging into the hidden test pads of these devices. You’ve heard of Folding@Home, but what about Minecraft@Home, the effort to find world seeds from screenshots. And when USB chargers have exposed and rewritable firmware, what could possibly go wrong?

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (60 MB or so.)

Continue reading “Hackaday Podcast 077: Secret Life Of SD Cards, Mining Minecraft’s Secret Seed, BadPower Is Bad, And Sailing A Sea Of Neon” →

A Tin Can Modem, Just For Fun

July 18, 2020 by Dan Maloney 9 Comments

Anyone old enough to fondly recall the “bleep-burp-rattle” sequence of sounds of a modem negotiating a connection over a phone line probably also remembers the simple “tin-can telephone” experiment, where a taut string transmits sound vibrations from the bottom of one tin can to another. This tin can modem experiment puts both of those experiences together in a single project.

As [Mike Kohn] notes, this project was harder than it would seem that it should be. He actually had a much harder time getting the tin can phone part of the project optimized than getting the electronics sorted out, resulting in multiple tries with everything from the canonical tin cans to paper coffee cups before eventually settling on a pair of cardboard nut cans, the kinds with the metal bottoms. Linked together with a length of kite string — dental floss didn’t work — [Mike] added a transmitter on one end and a receiver on the other.

The transmitter used an ATtiny 2313 and everyone’s favorite audio amplifier, the LM386, while the receiver sported an electret mike preamp board, an LM566 tone decoder, and an MSP430 microcontroller. The modulation scheme was as simple as possible — a 400 Hz tone whose length varies whether it’s a one or a zero, or a stop or start bit. Connected to a pair of terminal programs, [Mike] was able to send his name over the ~~wire~~ string at what he calculates to be six or seven baud.

This project has all the hallmarks of lockdown boredom, but we don’t care because it’s good fun and a great learning opportunity, particularly for the young ones. There’s plenty of room for optimization, too — maybe it could even get fast enough for the Hackaday Retro 300-baud challenge.

Continue reading “A Tin Can Modem, Just For Fun” →

Remote Code Execution On The N64

July 6, 2020 by Lewin Day 4 Comments

Some like to garden in their spare time, while others prefer to smoke cigars or fold complicated origami figurines. Security researcher ~~[grifter]~~ [CTurt] seems to enjoy cracking consoles instead, and had a go at exploiting the Nintendo 64 over an obscure modem interface.

The 1990s were a wild time, where games shipped in cartridges. This format opened up crazy possibilities to add additional hardware to the cartridge itself. Perhaps most famously, Nintendo packed in the SuperFX chip to enable 3D graphics on the Super Nintendo. Later on, the N64 game Morita Shogi 64 shipped with an entire telephone modem in the cartridge itself. The resulting exploit is therefore dubbed “shogihax”.

Armed with a dodgy GameShark and a decompiler, [CTurt] set to work. Through careful parsing of the code, they were able to find a suitable overflow bug in the game when using the modem. Unlike more pedestrian savegame hacks, this not only allowed for the execution of arbitrary code but also the modem interface means that it’s possible to continually stream more data to the console on an ad-hoc basis.

It’s a great hack that takes advantage of a relatively accessible cartridge, rather than relying on more obscure hardware such as the N64DD modem or other rarities. We’ve seen other N64 homebrew hacks before, too. Video after the break.

Thanks to [grifter] for the tip!

Continue reading “Remote Code Execution On The N64” →

An Open Hardware Modem For The Modern Era

June 9, 2020 by Tom Nardi 39 Comments

Readers of a certain age will no doubt remember the external modems that used to sit next to their computers, with the madly flashing LEDs and cacophony of familiar squeals announcing your impending connection to a realm of infinite possibilities. By comparison, connecting to the Internet these days is about as exciting as flicking on the kitchen light. Perhaps even less so.

But while we don’t use them to connect our devices to the Internet anymore, that doesn’t mean the analog modem is completely without its use. The OpenModem by [Mark Qvist] is an open hardware and software audio frequency-shift keying (AFSK) modem that recalls some of the charm (and connection speeds) of those early devices.

It’s intended primarily for packet radio communications, and as such is designed to tie into a radio’s Push-to-Talk functionality with a standard 3.5 mm jack connector. Support for AES-128 encryption means it will take a bit more than an RTL-SDR to eavesdrop on your communications. Though if you’re really worried about others listening in, the project page says you could even use the OpenModem over a wired connection as you would have in the old days.

If you just want a simple and reliable way to get a secure AFSK communication link going, the OpenModem looks like it would be a great choice. But more than that, it offers a compelling platform for learning and experimentation. The hardware is compatible with the Arduino IDE, so you can even write your own firmware should you want to spin up your own take on this classic communications device.

The OpenModem is the evolution of the MicroModem that [Mark] developed years ago, and it’s clear that the project has come a long way since then. Of course, if you’re more about the look than the underlying technology, you could always just put a WiFi access point into the case of an old analog modem.

[Thanks to Boofdas for the tip.]

Easy Internet For Retro Computers With The PiModem

June 1, 2020 by Lewin Day 34 Comments

Retro computers are great, but what really makes a computer special is how many other computers it can talk to. It’s all about the network! Often, getting these vintage rigs online requires a significant investment in dusty old network cards from eBay and hunting down long-corrupted driver discs to lace everything together. A more modern alternative is to use something like PiModem to do the job instead.

PiModem consists of using a Raspberry Pi Zero W to emulate a serial modem, providing older systems with a link to the outside world. This involves setting up the Pi to use its hardware serial port to communicate with the computer in question. A level shifter is usually required, as well as a small hack to enable hardware flow control where necessary. It’s then a simple matter of using tcpser and pppd so you can talk to telnet BBSs and the wider Internet at large.

It’s a tidy hack that makes getting an old machine online much cheaper and easier than using hardware of the era. We’ve seen similar work before, too!