Network Hacks

139 Articles

Basics Of Remote Cellular Access: Connecting Via VPN

January 14, 2021 by 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” →

Leaking Data Slowly By Switching Ethernet Speeds

November 30, 2020 by 9 Comments

Airgapping refers to running a machine or machines without connections to external networks. Literally, a gap of air exists between the machine and the outside world. These measures present a challenge to those wishing to exfiltrate data from such a machine, leading to some creative hacks. [Jacek] has recently been experimenting with leaking data via Ethernet adapters.

The hack builds on [Jacek]’s earlier work with the Raspberry Pi 4, in which the onboard adapter is rapidly switched between 10 and 100 Megabit modes to create a signal that can be picked up via radio up to 100 meters away. Since then, [Jacek] determined the Raspberry Pi 4, or at least his particular one, seems to be very leaky of RF energy from the Ethernet port. He decided to delve deeper by trying the same hack out on other hardware.

Using a pair of Dell laptops connected back to back with an Ethernet cable, the same speed-switching trick was employed. However, most hardware takes longer to switch speeds than the Pi 4; usually on the order of 2-5 seconds. This limited the signalling speed, but [Jacek] was able to set this up to exfiltrate data using QRSS, also known as very slow speed Morse code. The best result was picking up a signal from 10 meters away, although [Jacek] suspects this could be improved with better antenna hardware.

While slow data rates and the one-way nature of such communication limit the utility of such an attack, it nonetheless shows that securing a machine isn’t as simple as unplugging it from the network. We’ve done a feature on such hacks before for those interested in learning more. Video after the break.

Continue reading “Leaking Data Slowly By Switching Ethernet Speeds” →

Tiny Ethernet Routers Now Available In Gigabit Speeds

November 26, 2020 by 60 Comments

If you need to move a lot of data, and fast, Gigabit Ethernet is a great way to do it. However, most network hardware outside of datacenters is fairly space inefficient, a headache if you’re building a robot or drone. Enter the Gigablox, a super-compact Gigabit router for just these applications.

The Gigablox takes its mission seriously, with its compact size the ultimate design goal. The entire switch fits on a tiny 45 mm x 45 mm PCB. To this end, it eschews the common RJ45 connector, which is bulkier than necessary. Instead, thin Molex PicoBlade connectors are used for the five ports on board. Cables are included to convert between the two connectors, and obviously crimping ones own is easy to do, too. For those who need to connect more devices, several Gigablox can be hooked up in the same way as any other Ethernet switch. The Gigablox is a non-blocking switch, too – meaning all five ports can run at full speed simultaneously.

The design is the sequel to the SwitchBlox, and the later SwitchBlox Nano, both designed by [Josh Elijah] earlier this year. The pace of development is impressive, and it’s great to see [Josh] bring Gigabit speeds to the compact form factor. We can imagine a few good uses for these boards; share your best ideas in the comments below! Video after the break.

Continue reading “Tiny Ethernet Routers Now Available In Gigabit Speeds” →

DSL Is Barely Hanging On The Line As Telcos Stop Selling New Service

October 29, 2020 by 154 Comments

Are you reading this over AT&T DSL right now? If so, you might have to upgrade or go shopping for a new ISP soon. AT&T quietly stopped selling new traditional DSLs on October 1st, though they will continue to sell their upgraded fiber-to-the-node version. This leaves a gigantic digital divide, as only 28% of AT&T’s 21-state territory has been built out with full fiber to the home, and the company says they have done almost all of the fiber expansion that they intend to do. AT&T’s upgraded DSL offering is a fiber and copper hybrid, where fiber ends at the network node closest to the subscriber’s home, and the local loop is still over copper or coax.

At about the same time, a report came out written jointly by members of the Communications Workers of America union and a digital inclusion advocacy group. The report alleges that AT&T targets wealthy and non-rural areas for full fiber upgrades, leaving the rest of the country in the dark.

As the internet has been the glue holding these unprecedented times together, this news comes as a slap in the face to many rural customers who are trying to work, attend school, and see doctors over various videoconferencing services.

If you live in a big enough city, chances are you haven’t thought of DSL for about twenty years, if ever. It may surprise you to learn of the popularity of ADSL in the United Kindom. ADSL the main source of broadband in the UK until 2017, having been offset by the rise of fibre-to-the-cabinet (FTTC) connections. However, this Ofcom report shows that in 2018 ADSL still made up more than a third of all UK broadband connections.

Why do people still have it, and what are they supposed to do in the States when it dries up?

Continue reading “DSL Is Barely Hanging On The Line As Telcos Stop Selling New Service” →

Ethernet At 40: From A Napkin Sketch To Multi-Gigabit Links

October 19, 2020 by 50 Comments

September 30th, 1980 is the day when Ethernet was first commercially introduced, making it exactly forty years ago this year. It was first defined in a patent filed by Xerox as a 10 Mb/s networking protocol in 1975, introduced to the market in 1980 and subsequently standardized in 1983 by the IEEE as IEEE 802.3. Over the next thirty-seven years, this standard would see numerous updates and revisions.

Included in the present Ethernet standard are not just the different speed grades from the original 10 Mbit/s to today’s maximum 400 Gb/s speeds, but also the countless changes to the core protocol to enable these ever higher data rates, not to mention new applications of Ethernet such as power delivery and backplane routing. The reliability and cost-effectiveness of Ethernet would result in the 1990 10BASE-T Ethernet standard (802.3i-1990) that gradually found itself implemented on desktop PCs.

With Ethernet these days being as present as the presumed luminiferous aether that it was named after, this seems like a good point to look at what made Ethernet so different from other solutions, and what changes it had to undergo to keep up with the demands of an ever-more interconnected world. Continue reading “Ethernet At 40: From A Napkin Sketch To Multi-Gigabit Links” →

Free P2P VPN

October 18, 2020 by 35 Comments

People use a VPN — virtual private network — for a lot of reasons. However, for many people it is synonymous with hiding your network traffic, one thing that VPN can do. FreePN is a relatively new open source project that aims to build a free peer-to-peer VPN network. Like TOR, it is decentralized.

Right now, you can download for Ubuntu and Gentoo. There is a way to ask for early access for Debian, Fedora, and Arch. Windows, iOS, MacOS, and Android versions are promised for the future.

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Low-Level Academy Gets Into Details

October 16, 2020 by 7 Comments

We often say that you don’t have to know how an engine works to drive a car, but you can bet that every driver at the Indy 500 knows exactly how it works. You could say the same for computers. You don’t need to understand the details, but it really helps, especially if something goes wrong. [Low-Level Academy] has an online class where you can program in Rust inside your browser to learn about low-level TCP and UDP networking details.

Just how low it goes, we aren’t exactly sure, yet. There are three of eight modules ready to go. The first three cover number encoding, exchanging messages with UDP, and fragmentation. Reliability, routing, server programming, TCP, and HTTP are not out yet, but the ultimate project is a web server. In addition, new modules are released to sponsors first, so the fragmentation module for example won’t be available for a few more days. While that seems unorthodox, it is no different than having to wait for an HBO show to show up on basic cable in reruns.

Continue reading “Low-Level Academy Gets Into Details” →