Netz-AK went 39C3

This year, we had the opportunity to attend Europe’s largest hacker congress—the 39C3, the 39th Chaos Communication Congress. It is a four-day event organized by the Chaos Computer Club, held annually and now once again at the Congress Center Hamburg (CCH).

Here are three good reasons to attend the C3:

(1) Talks
A core element of the Congress—and probably the main reason for its public visibility. In the past, talks that made it into major media outlets included “We Know Where Your Car Is” (location histories of all recent Volkswagen vehicles, including those of government and intelligence employees, freely accessible on the internet), “The Electronic Patient Record Is Coming – Now for Everyone!” (severe security issues in the implementation of the largest digitization project in the German healthcare system), or “Operation Triangulation” (in which security experts from Kaspersky presented a zero-click attack on Apple mobile devices they had discovered).

Talks run throughout the entire Congress in four large halls. With more than 16,000 attendees this year, there was no shortage of content—and the limited time automatically ensures that only the most interesting submissions make it into the available slots. I personally watched, for example, “Excuse me, what precise time is it?”, in which the speaker presented and live-demonstrated various methods of microsecond-accurate network time synchronization. And of course, the “Security Nightmares” were a must again this year.

(2) Networking with other assemblies, meeting familiar faces again
Tables are set up all over the exhibition grounds—these tables belong to so-called “assemblies,” i.e., groups or associations. The C3-Nav gives a good impression of the venue—and the sheer number of groups present. When you’re not attending a talk, walking through the halls, or eating, these tables are typically the go-to place to retreat to. We were kindly hosted by the Chaostreff Tübingen—many thanks for that!

Right next to us, Selfnet e.V. from Stuttgart had their tables—the operator of the student dormitory network for Stuttgart, Esslingen, and Ludwigsburg. Two experienced members spontaneously took the time to give me a virtual tour of their dormitory network, and we talked about topics such as switch selection, Wi-Fi access points, redundancy, automation, and routing. I definitely took away a few new ideas—on the never-ending journey of continuously improving our own dormitory network.

At least two of our members also unexpectedly ran into other acquaintances—the (IT) world really is smaller than you think.

(3) Booths, hands-on events, venue, music

As can be seen on the aforementioned C3-Nav, the CCH is truly huge—and every room has its own design and music. The decoration team once again went all out and created something impressive. Many assembly tables are also used as booths, and there are small events and “self-organized sessions” you can take part in. In one of these sessions, for example, you could learn SMD soldering.

Unfortunately, there are only a few photos of the Congress—mainly because of the strict policy that you may not take photos unless you have explicitly asked every single person in the picture. This is meant to ensure a relaxed and low-pressure experience for everyone. Still, you can get a visual impression here, here, here, and here.

Many of the talks were recorded—if this blog post has sparked your interest, you’ll find plenty of content on media.ccc.de and on the YouTube channel.

Attending the 39C3 was a fantastic experience and definitely worth repeating. Thank you very much for the opportunity!

2025-12-07 Partwise outage of Pestalozzistr. 63

Due to an oversight on my part, I have unfortunately taken Pestalozzistr. 63 partially offline. I apologize for this. I will take care of getting you back online today.

Update: Pestalozzistr. is back online.

2025-12-07 Outage Eugenstr.

Our monitoring solutions indicate that it can no longer reach our switches in Eugenstr. The reason for this is not entirely clear; it could be due to a switch that has died of old age or to some kind of problem with the uplink.

We will take care of it today.

Update: Eugenstr. is back online – if problems are still appearant, please contact us.

2025-11-15 Exchange of Switches in Fruwirthstr. 3, 7 & 9

Hello everyone,

During the course of the evening, we will be replacing switches at Fruwirthstr. 3, 7, and 9, which will cause the internet to be down for approximately one hour at each location.

We will let you know as soon as we are done – everything should be working again by tomorrow morning at the latest!

Update 9:42 p.m.: Fruwirthstr. 3 has already been completed—if you encounter any problems, please report them as soon as possible!

Update 00:28: Fruwirthstr. 7&9 have also been swapped—and we’re back in Tübingen.

So you should all have internet again – and new switches that will last a long time. 🙂

2025-10-15 Partial Outage in Fichtenweg 1

Around 12:10, one of the two switches at Fichtenweg 1 failed, causing most of the rooms to currently have no internet connection.

 

We are on our way to replace the switch.

Update: since 1:27 pm the house is online again. The priority to upgrade this house has been increased.

2025-09-14 Maintenance Geissweg

Long awaited – this evening, we are upgrading the Geissweg to Gigabit. During the the work on the switches, the internet there won’t work.

We’ll update this site post as soon as we’re finished.

Update 8:06 PM: Everything back online – now 10x as fast!

Addendum to the outage in Albstadt on 2025-06-04

We had an outage in Albstadt for several days on June 4 this year – in connection with a power failure there. So something happened, a lightning strike or something.

2025-06-04 Outage Albstadt

A member from Albstadt brought the switches to our weekly meeting today and we unscrewed them to see what had happened – when we plugged them in, they no longer started up.

Our analysis: A capacitor in the power supply unit has been smashed due to too much current.

Switch 1:

Switch 2, more detailed, also with the part separated from the rest:

 

2025-06-04 Outage Albstadt

At around 03:00, the internet connection of the dorms in Albstadt went down. As the time is pretty even, this could be some kind of planned maintenance work regarding infrastructure outside our control – but nothing was announced to us.

If the problem persists tomorrow, somebody of us has to visit the network room in Albstadt physically.

Update 8:30 AM:There is a major power issue at Poststraße 22/1. Without electricity, our equipment doesn’t work.
Poststraße 22/2 is connected to 22/1, so it is also offline.

Update 7 PM: we are still waiting for power.

Update 2025-06-04 10:30 AM: we are still waiting for power.

Update Friday, 2025-06-06, 8:30 AM:

Unfortunately, there are no new developments. Three circuit breakers are off. When one of them was switched back on, smoke appeared. For safety reasons, the Netz-AK will not touch these breakers or power outlets.

Our network infrastructure has no power and is completely offline. Normally, power supply is not our responsibility – but since nothing has happened so far, we are now checking with the Studierendenwerk to find out if and when an electrician will come for repairs.

If the issue is not fixed today, we will look into other ways to power our devices. At the moment, we cannot say whether that will work.

We, too, are surprised by how long the power outage is lasting and how it affects hot water and the network. We’ll keep you updated.

Update 12:50 PM: Something seems to have been fixed, but some spare parts had to be ordered. Since we only have information from third parties, we are not sharing any details.
We are now looking for a power source to get our switches running again.

Update Saturday, June 7, 11:30 AM:

We got in the car in Tübingen at 8:30 AM and drove to Albstadt because our team member on-site “couldn’t” access the room yesterday.

When we arrived at Poststraße, the tech room was dark. According to our info, there’s no power there. There are no alternative power sources nearby, but we happened to meet an electrician who wanted to fix the lights.

Now we have first-hand information we can share.

On Wednesday, there was an overvoltage, probably from a lightning strike.

The electrician already replaced the fuses on Wednesday and found that our hardware (network switches) was burned out. He informed the caretaker.

So we are not waiting for electricity or a big repair — we just need to install new devices.

We have everything in stock in Tübingen, but we didn’t bring the devices because we thought the only problem was missing power.

We could have replaced everything already on Wednesday, no probem at all.

Someone from our team will go back to Albstadt during Pentecost and install the replacements.

If you’re frustrated, please contact the Studierendenwerk directly…

Update Sunday, June 8, 6:50 PM:

Poststraße 22-2 is already back online, and room by room, the network is coming back.

Big thanks to the person who lent their car to our AK member on site, so the switches could be picked up in Tübingen and brought to Albstadt.

You should all be back online very soon.

2025-03-26 Outages with connection to the current Tübingen power outage

There is currently no internet in Heuberger-Tor-Weg – this is almost certainly to do with the power cut here. It could be that the internet is also down in many other halls of residence. Our server room also seems to have no power at the moment and is only being kept running by the UPS, which will also run out of power at some point.

Power failure: https://www.swtue.de/netze/netzinformationen/aktuelle-meldungen.html

Update 12:05 PM: There is power in the server room, so we won’t suffer a total outage.

Update 1.36 pm: Welcome back online!