Andreas Happe: tech

Building a 4G/LTE router+accesspoint using hostapd, network-manager and modemmanager

So I’ve been using a Raspberry Pi 4b+ together with a WaveShare LTE Modem as 4G router/access-point for my home network setup. I do like my hardware to be quiet and thus fan-less, alas the Raspberry Pi 4b+ gets a tad on the warm side. So this was a perfect opportunitiy to play around with an older Raspberry Pi 3b+ which should use approx. 20-25% less power (both, during idle and load) and with “new” software.

February 11, 2022 in Linux Tech

Running OWASP Juice Shop with Root-the-Box on Google Cloud Platform

So I am back at teaching web application security. This time I wanted to setup a CTF challenge for my students. To not reinvent the wheel, or rather, to stand on the shoulders of giants I am reusing the OWASP Juice Shop vulnerable web app in its CTF mode. Normally I would teach at a (physical) lab which would make the setup easy: all students are situated in the same physical room, I can setup the game server on my laptop and distribute virtual machines containing the vulnerable web app over the local network.

December 2, 2020 in tech

Create a new Ubuntu 20.10 Desktop without too much Ubuntiness.

After I’ve bought a new and fast 1TB SSD, it’s time to setup my aging Desktop again. Last time I went with Fedora Core, this time I will try to reduce some of the ubuntu-iness of a Ubuntu 20.10 Desktop for that. After preliminary tests Ubuntu seems to be more resource efficient than Fedora Silverblue and I should be able to remove most of Ubuntu’s problematic packages. Given that my Notebook still runs Fedora Core, I’m also keeping in touch with both the Ubuntu/Debian as well as with the Redhat/Fedora world through that.

October 13, 2020 in tech linux

Building a simple VPN with WireGuard with a Raspberry Pi as Server

Now that wireguard will be part of the upcoming Linux 5.6 Kernel it’s time to see how to best integrate it with my Raspberry Pi based LTE-Router/Access Point Setup. What is my scenario? Raspberry Pi 3 with a LTE hat, using a public IP address. This will be the VPN server (called edgewalker in this post) An Android Phone that should use the VPN for all communication when connected An Linux Laptop that should use the VPN only accessing network services that are exposed to the VPN Each device connected to the VPN should be able to connect to all other devices, e.

January 29, 2020 in tech

Adding advertisement-filtering and spotify support to a Linux-based Access Point/Router

The last weeks I’ve tried to improve upon my Raspberry Pi based LTE-Router/Access Point. Normally I would heave tons of software on it, try it out and let it simmer on. I did that this time too: the ELK-Stack (too little memory) and HomeAssistant (too little SmartHome-devices in my flat) only had a short intermezzo on this hardware. What stuck? Before that a small note: originally I was using a IKEA USB charger; its spec should be sufficient but I kept getting “Undervoltage detected” error messages in dmesg/syslog.

December 8, 2019 in tech

Building a secure torrent download station by combining Private Internet Access (PIA), OpenVPN and transmission through docker

Sometimes I want to work on client assignments (penetration-tests) from home, if I do that I am using my company VPN so that all traffic is routed thorugh their public IP address (which is white-listed by the client). I do not want for traffic to ever leave that VPN as that would look like as if I’d be performing cyber attacks from my private home IP address. The same requirements arise for different use-cases, e.

August 5, 2019 in tech

How to create a (good-looking) PDF and Kindle eBook from LaTeX

So I held a lecture on “Web Application Security” for the FH/Technikum Wien last spring and wrote a small booklet for my students (partially because I wanted to avoid discussions during the final exam). I did volunteer for a anonymous feedback round which turned out very positive for me, the booklet was repeatatly mentioned positively. So I distilled and refined it, tried to improve its focus. As I will do the same lecture next year, I am in dire need of feedback so that I can improve it, so I went to dark places and published it on reddit.

July 29, 2019 in tech

LTE uplink for Raspberry Pi: Huawei E3372 vs Waveshare SIM7600E-H

I spent some time playing around with various LTE-options for my Raspberry Pi Access Point/Router setup. My Huawei E3372 USB LTE modem works find but only implements a fake network card. This means that a virtual network card is emulated, all traffic is NATted over a virtual router located behind that virtual network card. This happens in addition to the network translation (NAT) that my Raspberry Pi access point already does.

July 5, 2019 in tech

Books and influences of mine

Most of you (and there are a couple of thousands of you) come for my tech-posts, but it seems that some of you get lost reading my non-techie posts too. Time to add on of those, it’s been a while.. I breathe books, they give my brain constant input to thrive on. Recently I went through my goodreads list of reread-good-books to check what influences me and started to reread some of them.

June 26, 2019 in life tech books

Building an LTE Access Point with a Raspberry Pi

In one of my last experiments I replaced my crappy T-Mobile (now Magenta) 4G modem/access point with an OpenWRT-based cheap travel router and a 4G USB LTE modem. That doubled my speed over the wireless (WLAN) network but the setup was limited by the outdated and under-powered travel rooter. So I got myself a cheap Raspberry Pi 3b+ and created a minimal Linux-based 4G router/access-point. My basic goal was to create the minimal feasible configuration so that I have a good starting point for future IoT/VPN/SmartHome experiments.

June 22, 2019 in tech