Articles by author: Stefan
For a given occasion I wrote Small Python script to test a domain for DMARC, DKIM and SPF records. Those records are managed in a DNS Zone and are typically used in Anti-SPAM techniques.
In my newest blog post I show how to setup Netbox with Active Directory as backend for users and groups.
This is my new concept for DNS security with Bind9, Pi-hole and OpenDNS in my network. Bind9 is used as Enterprise DNS to resolve hostnames and IP addresses in the local area network, Pi-hole and OpenDNS are used for Internet DNS traffic. DNS traffic is passed by Cisco ASA Firewall ACL.
Screenshots of Pi-hole installation on Debian Linux
Humble Book Bundle - The Ultimate Python Bookshelf by Packt including Data Analysis, Artificial Intelligence, Machine Learning, Django, Automation
Blocking of Google Chrome FLoC (Federated Learning of Cohorts) on my web server
Weeks of the data leaks and my approach after data leaks or breaches
Automatically install security-related upgrades on Debian Linux with unattended-upgrades
Most useful tip from Cisco Live 2021 and it's implementation
Fritzbox rack mounted on a 19" shelf and it's hardware issues: white description on a white box, no LED on ports for activity, height unit issues, Square wood and Velcro to fix ;)
This is the third part of a series of blog posts about Cisco configuration backup with Netbox and Gitlab. This blog post covers the check in of configuration files to a Gitlab server
This is the second part of a series of blog posts about Cisco configuration backup with Netbox and Gitlab. This blog post covers the low level functions to connect to network devices with pexpect.
This is the first part of a series of blog posts about Cisco configuration backup with Netbox and Gitlab. It covers the connection to the Netbox API and to get the data of network devices with the pynetbox filter function.
In case of fire: Leave the building before posting it on social media
Setup of two redundant Cisco ASA firewalls on a Fritzbox cable modem with Non-routed transfer network to keep the "PC-MAC"/"exposed host" configuration on Fritzbox during ASA failover switching
Cisco Smart Software Manager (SSM) On-Prem Test Drive installation, Virtual Machine setup and first steps in the Web UI
Humblebundle.com has a nice books bundle of Programming Fundamentals, available as PDF and as EPUB, DRM-free
Upgrading memory on my XCP-NG hypervisor servers from 32Gb RAM to 64Gb RAM
The blog post shows a Python script which can look up an Asset tag in Snipe-IT with a generated QR code
Creating QR code for wireless networks and a MeCard with Linux
Official Cert Guide Cisco Certified DevNet Associate DEV ASC 200-901 book available and arrived from the USA to Germany.
Some thoughts after the Cisco DevNet Create Live Event
Learning material for network automation with books, videos, podcasts, courses and API, libraries and tools
Installing Gitlab on Debian Linux and connecting with Atom editor
After an upgrade to the new released version 2.9.0 of NetBox the Login failed with Server Error (Missing required package/WSGI service not restarted after upgrade)
Python scripts with API calls as Custom Links for Snipe-IT and LibreNMS.
Today DEF CON 28 is starting in Safe Mode with Networking
Integration of Snipe-IT Asset Management into Netbox DCIM/IPAM as Custom Link with a PHP script and using Snipe-IT API call.
Moving my website to Pelican (Static Site Generator) with introduction to my toolchain, tricks for development, pelican-plugins used on my website and design changes and other improvements
Screenshots of XCP-NG Upgrade to 8.1
Upgrading XCP-NG Hypervisor from version 7.6 to 8.1 remotely over VPN connection and KVM. Fixing IPTables and SNMP configuration for monitoring system.
This is the third part of a series of blog posts covering my new netbox installation. This part shows how to integrate NAPALM and Graphs on device Interfaces from the Monitoring system LibreNMS.
This is the second part of a series of blog posts covering my new netbox installation. The rack is filled up with the rest of the hardware and each network port is getting cabled. This part contains also IPAM (IP Address Management) and handling of Provider and Circuits.
Screenshots of Netbox 2.8.5 installation
This is the first part of a series of blog posts covering my new netbox installation. It covers the defining of manufacturers, device types, power panels and power feeds. An UPS, Power Strips and two Cisco switches are added including their Power cabling. As bonus, the Cisco switches are build as Virtual Chassis (Cisco Switch-stack).
Cisco CleanAir quality report for 2.4GHz WiFi in my area
Useful Cisco Commands for Troubleshooting problematic cabling (Cat.x and Fiber optics).
Simple High Availability with CARP (Common Address Redundancy Protocol)
Cisco Live 2020 Barcelona, Day #5 - SD-WAN, deployment strategies, managing and monitoring
Cisco Live 2020 Barcelona, Day #4 - Catalyst 9000 Access Switching Architecture and Resolving Network Faults Faster through Automating Entire Fault Management
Cisco Live 2020 Barcelona, Day #3 - About Garlic and Onions and Industrial automation
Cisco Live 2020 Barcelona, Day #2 - Attack Kill Chain and Packet Capturing
Cisco Live 2020 Barcelona, Day #1 - A cat and mouse Game
Simple load balancing with Apache proxy_balancer and testing with siege
Replacing faulty memory for Cisco ASA-5520, checking memory and failover
Princeton University and University of Chicago published a study of the tracking Ecosystem of Over-the-Top TV Streaming Devices
Humblebundle.com has a nice books bundle of Linux + Unix books by O'Reilly. And a tipp for the best Currywurst: Bruzzelhütte, Hamburg
NetBox, Snipe-It and LibreNMS: Three tools for Data Center Information Management (DCIM), IT Asset Management (ITAM) and Network Monitoring System (NMS).
Cisco ASA5520 stuck at Booting system, please wait... and how to check for faulty memory
Bookmarks and links to Security and security research related web sites
Bookmarks and links to various other blogs and websites
Bookmarks and links to various Podcasts and Video channels
The procedure how to convert a Cisco lightweight AP to a standalone AP
Humblebundle.com has a nice books bundle of IT Security books, available as PDF and as EPUB, DRM-free
Cisco Unified IP Phone 7975G with Sipgate, from configuring switches, setting up DHCP and TFTP, and do the correct SEPMAC.cnf.xml file configuration and firewall ACL.
Building a High-Availability cluster with XCP-NG
Bookmarks and links to Free and open source software web sites
Alienware laptop hardware replacement
Pictures of my Alienware A51 Laptops
Connecting to Cisco console with Linux
Bookmarks and links to various RSS feeds
Testing Panduit CBOT24K cabling organizer
Creating ROOT-CA-based certificates for Cisco Wireless Controller
Creating ROOT-CA-based certificates for Synology Diskstation
Blocking Facebooks networks on ASA firewall
35C3 and braindump about blocking of facebooks network range
Liste der Datenschutzbehoerden in Deutschland
How to securely put your boarding pass on the internet
Oh no, snow
Schnitzel Day (with Wiener Schnitzel) in Germany
Setting up Cisco 3504 series wireless controller redundancy
Bilder meiner Reise nach Hamburg Germany im August 2018
In Germany... Hacker-Conference comes to you
Setting up administrative RADIUS logins on AIR-AP2800 with Mobility Express
WiFicalypse continued, new method to speed up cracking of WPAv1 / WPAv2 Pre-sharded keys
A Trick to activate CLI Commands on Cisco Lightweight AP
Some impressions of the lunar eclipse 2018 over Germany
saveconfig, two scripts to backup configuration files from network devices
Optimierungen und Static Site Generator, Automatisierung für meine Website
The Cisco hardware I have at home
A simple bash script to create ASA Firewall rules from Talos IP Blacklist
Anmerkungen zum Independence Day und Website Updates mit Volltext-Suche
Ältere Bilder meiner Modelleisenbahn (Lokomotiven und Wagen)
Bilder meiner Reise nach Metepec, Mexico im April und Mai 2018, Metepec Downtown, Los Foquitos
Added GDPR - General Data Protection Regulation / DSGVO - Datenschutzgrundverordnung
Icebound. Too much snow and ice for me.
Travel to Germany, returned with some fun stuff
WiFicalypse Update with vendor lists, press statements
WiFicalypse, KrackAttack to break WPA version 2
WiFi Spectrum Analysis with Cisco 3600 Series AP and Outdoor antenna
Websites updates, my old website thierolf.org is back online, yeah!
Mein privates Cisco Lab mit Switches, Firewall, Routers, WiFi Controller
Changing Rsyslog's default template for a MariaDB database
Bilder der Solar Eclipse 2017 aus New Hampshire, USA
Solar Eclipse 2017, Impressionen der Sonnenfinsternis aus New Hampshire, USA
Cyber-Feuerwehr and Cyber-System failure
A quick overview of the 802.11 standards for Wireless networks
Theme and website updates and ticket for 34C3
Website updates and SHA2017 videos on CCC media server
CSAchecker, a Cisco Security Advisory checker
Short instructions how to convert a Cisco 2600 Series Access Point
Overview of common Cisco switch port errors and causes
Bilder meiner Reise nach Metepec, Mexico im April 2017, Metepec Downtown und der Hill of the Magueyes
Travel to Mexico: Photos of my trip from Metepec downtown
Verschiedene Bilder aus den USA
How to secure the Cisco console with AAA
Snow snow snow: After Winter Storm Orson
New Cisco switch for my network: WS-C3750G-24TS-S1U
How to move SSH port on Cisco devices to another port than TCP/22
Playing Elite:Dangerous - Welcome KEY-LOH-OSS-CAH-NO-VEM-BER.
Updated links and new Alienware laptop after my return flight to the US
How to setup Postfix as satellite System (smarthost)
Bilder meines Alienware 17 Laptops
Website update mit Flex Box, Motto: Vom Hirn ins Terminal seit 1998.
Spass mit der Console: Cowsay fortunes mit lolcat unter Debian Jessie
Sicherer Mail server fertig, mit Crypto und so
Neue Website online (Mal wieder richtige Website anstelle einer Mail-Info)
The Cisco hardware I have at home
Bilder meiner Reise nach Wuxi China und Pattaya Thailand im September 2015
Bilder meiner Reise nach Queretaro Mexico im November 2014
Travel to Old Sarum, England in 2012
Travel to Stonehenge, England in 2012
Travel to Woodhenge, England in 2012
Travel to Berlin, Pergamon Museum in 2012
Bilder meiner Reise nach New Dehli, India in 2012
Bilder meiner Reise nach Sao Paulo, Brasilien im November 2011, Sao Paulo Downtown
Bilder meiner Reise nach England im August 2010, Dover harbour
Roman castle, Richborough England, 2010