2022-06-01 HackTheBox Cyber Apocalypse CTF 2022 - Intergalactic Chase
With a team of people from work we participated in this years HackTheBox Cyber Apocalypse CTF 2022. And while my teammates managed to solve several challenges, some of them with some thinking from me, I personally solved zero challenges. Which was a bit dissapointing. I was especially interested in the hardware hacking challenges because that is a subject I am quite interested in.
Hardware / Space pulsesThis challenge had a .sal file. After I learned about Salea Logic Analyzer in the 2021 HackTheBox Cyber Apocalypse I opened the file in this logic analyzer and started trying to find out what I was looking at. It was a one-channel digital signal. It turned out to have a variable duty cycle, with complete cycles being 255 and a bit milliseconds. I noticed the maximum duty cycle was somewhat less than 50%. I spent a lot of time trying to decode this, mostly thinking in the direction of it being a pulse width encoded signal with probably 4 bits of information per cycle to get 54 characters which seemed reasonable for a flag. But with the assumption that the smallest pulse is the representation of 0000 and the widest pulse is the representation of 1111 I could not get valid data from it, and it was nowhere near decoding a flag. I was sure I was overthinking it somewhere, but couldn't find out where. A while after the CTF I read Writeup] Cyber Apocalypse 2022 — Space Pulse [Hardware] and I obviously made a big "D'Oh!" sound as I was getting to the solution, but indeed overthinking it.
Hardware / Secret CodesWith this challenge I also downloaded a .sal file with two signals: a digital one and an analog one. The digital one stops after the first 'databurst' while the analog one is clearly the 'unpolished' version of the digital signal. I first tried to decode the digital signal as an async serial signal and found nothing. I also tried manchester encoding and also found nothing. Staring and pondering never fixed this. I found a writeup at HTB 2022 Cyber Apocalypse CTF - Hardware - Secret Codes which made me go "D'Oh!" again: it was manchester encoding. BUT (big but) Manchester encoding has 2 changes per bit and I left the bitrate at the same as for the async serial decoder.
2022-05-30 I participated in the CQ WPX CW contest
Last weekend was the CQ World Wide WPX Contest CW organized by CQ Amateur Radio magazine. The term 'WPX' stands for 'Worked All Prefixes'. The objective of this contest is to get contacts and exchange information with as many different other radio amateurs using morse code. Points are awarded for each contact, based on which amateur band and whether they are in the same or different continents. Multipliers are calculated from the number of different prefixes contacted. The prefix of my callsign PE4KH is PE4 which is a different prefix from for example PE3. This is a 48-hour contest. A good reason for me to participate was to practise my morse in contesting skills. Those skills still need work as I had trouble understanding the serial numbers. But with a bit of asking for a retransmission or guessing from the previous/next serial it sort of worked out for me. I felt like I had a lot more trouble understanding the serial numbers compared to a week ago in the King of Spain CW contest. I guess my call PE4KH is now in the list(s) of regular contest calls. When my callsign is repeated completely, it's never a PE4KS. In morse, an H is four dots .... and an S is three dots .... In the first few contests I had to correct PE4KS a few times, or ended in the log with the wrong call, so this feels to me like my call is now more familiair. I got 102 contacts in the log. I operated Saturday afternoon and parts of the evening, and late Sunday evening, wrapped around things like sleeping and other things in the weekend. I got one new country in the log: Mongolia. And I made my first morse contacts to Japan, China and Malta. The score table:Band 160 80 40 20 15 10 QSO's 0 0 31 71 0 0 Pts: 144 Mul: 84 Score: 12096
2022-05-23 I participated in the King of Spain CW contest
Since I have been learning morse code and passed the morse exam I notice I get more enjoyment out of contacts in morse code than out of contacts in digital modes. In digital modes (FT8) it is the computer doing hard work decoding and there isn't much variation, in morse I do the decoding and contacts can be from very simple confirmations of callsigns to longer chats about things. This also means I like chances to make morse contacts. One of the simple ways to make more morse contacts is to get involved in an amateur radio contest with morse. Last weekend was the His Majesty The King of Spain CW Contest and I participated. Before the contest I tried to build a contest scoring file for TLF Linux contest software. During the contest I found out the file wasn't correct as the score wasn't calculated correctly but I will debug that later. I participated Saturday evening and I made 41 contacts: 37 on the 20 meter band, 3 on the 10 meter band and 1 on the 40 meter band. That's 41 in total, which is not a lot: the minimum number to get a digital certificate in PDF format is 50 or 100 contacts. But I'm not doing this to win anything, I'm doing this to get more experience in morse and morse contesting. I still have trouble decoding morse at 'contest speed' so I use a morse decoder on the computer. There are moments it's a lot better at decoding a callsign at speed than I am, but sometimes I decode a serial number better than the computer does. This also mean I do all of this in 'search and pounce' mode, where I look for stations calling CQ TEST at a signal quality where I can decode the callsign with help from the computer, and I can hear whether they get my callsign correctly.Read the rest of I participated in the King of Spain CW contest
2022-05-18 A nice 10 meter opening to Italy, getting more WRTC stations in the log
Today when I had time to use the radio I noticed the 10 meter band was open. I had some nice contacts and saw II3WRTC on 10 meter FT8 and made the contact. II3WRTC is one of the WRTC 2022 Award stations and before today I had a lot of those in the log but none on the 10 meter band. I changed this quickly with II3WRTC on 10 meter SSB too, II9WRTC on 10 meter CW and II3WRTC on 10 meter RTTY.
2022-05-12 Generations of Netgear switches and interface names
In my time at Utrecht University computer science I wrote a script to search Cisco switches for a given ethernet address and respond with the port. This could be used to trace things on the network, which helped on incidents in progress. This script was based on the typical things Cisco switches do with vlan CAM table lookups and the best implementation. CAM stands for Content Addressable Memory: memory optimized for doing lookups by certain content. In the case of a network switch a 6-byte MAC address plus 2-byte vlan id will be used to do a lookup of the 2-byte interface number where it was last seen, and this lookup is done in hardware. This CAM table is accessible via SNMP, and the funny part is the MAC address for the lookup is also encoded as SNMP identifier. I could get the whole CAM table via snmpwalk but as I only want to lookup 1 MAC address it is way faster to go directly from MAC address to interface number. After that the interface number is translated to an interface name and that name is usually something recognizable to a network engineer. When I started using managed switches at home from Netgear I adapted the script at home and enhanced it for Netgear switches. I recently added a third netgear switch when upgrading the fiber to the shed and I updated the script to learn about the new switch. I noticed the interface names are quite different over the generations of netgear switches. The oldest switch is a Netgear GSM7224. The interface name from a query is "Unit: 1 Slot: 0 Port: 15 Gigabit - Level". The second switch is a Netgear GS716Tv2. The interface name from a query is "Slot: 0 Port: 11 Gigabit - Level". The newest switch is a Netgear GS310TP. The interface name from a query is "GigabitEthernet9". The Unit: 1 in the GSM7224 suggests some option for stacking multiple switches, but I can't find any mention of that option in the on-line documentation. The other fun part I notice is interface names never showing the fact that they are actually an SFP interface with an SFP in them. The port status for a port with an SFP is not different from the status for a copper cable at gigabit.
2022-05-11 The fiber to the shed network has been upgraded
I got around to doing the upgrade of the fiber to the shed network I had on my mind today. A friendly network layer 1 engineer had some leftover Cisco SFP modules and the netgear GS310TP and netgear GS716Tv2 switches accepted these without any issue. So the layer 1 network link came up fine. The layer 2 link with vlan support took me a few hours, somehow I managed to get confused with vlan tagging, vlan tagged only frames and the primary vlan id. I haven't done this in a while and I sort of copied the configuration from another port which may be less than optimal too. I had to run through the house a number of times to get the configuration right, wireless devices can't access the managed switches. At least I got the whole configuration working in the end. I think I can add other vlans to the link too (I want the option of a wireless access-point in the shed). Putting the switch, the power supply for the switch, the raspberry Pi, the power injector for the 1-wire measurement network and all network cables and fiber in the plastic box I bought for this work was a bit of work, it just fits (so a wireless access point will have to live outside that box..). But it's all in there and the box is closed again. It's just not airtight anymore with the new holes for power, fiber, network cable, gps antenna cable and 1-wire network. I may need to stuff the holes with foam or something similar to keep insects from crawling into the box. Everything works now and the measurements from the solar inverter are coming in!
2022-05-09 Grafana alerts working again
After reverting to Grafana 8.4.7 for a while because alerts were failing in Grafana 8.5.0 I had a look at the available version today and saw version 8.5.2. I assumed the problem with DataSourceNoData errors was fixed by now and did the upgrade. Indeed the alerts are seeing data fine now and I trust they will work when needed.
2022-05-08 Trip to Iceland day 15
Our flight was leaving Keflavik International airport at 07:40 so we wanted to walk through the door of the airport at 05:40 and return our car before that time. So the alarm went of at 05:00 and we put everything in the car and drove to the airport rental return area. Hertz has a huge parking area for returning rental cars so we parked in that area and walked to the return office. The office was still closed so we dropped the key in the key return box and walked to the main airport building. There we used a luggage cart and went to the check-in for our flight back home. The check-in was a bit of waiting but nothing really bad. After check-in it was time to go through the security check and even with a bit of extra checking of our luggage we were past that point fast. We found ourselves in the main waiting area for departing flights with lots of time to spare, so we finally had time to eat some breakfast and get an extra fresh juice. The flight back was fine, I decided to watch the film 'Rush Hour' from the entertainment system. Back in the Netherlands temperatures were higher again! We took the train from Schiphol airport back to our house.
2022-05-07 Trip to Iceland day 14
After breakfast we left the apartments and walked towards the center of the city and the main shopping street. Most of the shops were still closed in the morning. We changed plans a bit and visited the Reykjavík Park and Zoo which was more of a botanic garden. We tried to hop on a bus to get there but that was the first time we actually needed cash money. Trying to get the app for the Reykjavik bus working with a Dutch credit card also did not work. So we had to get actual money from an ATM to pay for bus trips. My wife and son went swimming for a while and we went back to the city center, now open. We walked along Laugavegur, which is the main street of Reykjavik. We also visited the Hallgrimskirkja which is a magnificent church building. Several signs were there to remind the tourists that it was also a house of worship.
2022-05-06 Trip to Iceland day 13Items with tag english before 2022-05-06
We woke up in Eldhestar hotel and had breakfast. My wife and son had booked a horse ride for the afternoon, so we had some hours before that started and visited Hveragerði. The area around Hveragerði has had several serious earthquakes. The library and shops building had an exhibition on the 2008 earthquake with pictures and stories from eyewitnesses. The building that this is all in has a scary detail of its own: during construction a huge crack in the earth was found right between the foundations. The decision was made to not build the 4 floor tower nearby and adapt the building to deal with earthquakes. Still the 2008 earthquake caused damage. To the north-east of Hveragerði is an area with lots of geothermal activity which can be hiked easily.