Articles by author: Stefan

Testing for Cisco security vulnerabilities with Ansible

Written by Stefan on Thu 11 May 2023. Posted in Blog.

In this blog post I'm demonstrating how to test for Cisco security vulnerabilities with Ansible.

Mastodon accounts

Written by Stefan on Tue 02 May 2023. Modified on Sat 06 May 2023. Posted in Bookmarks.

Bookmarks and links to various Cybersecurity, Infosec, dataprotection and privacy accounts on Mastodon

Add Virtual Machine to NetBox with an Ansible playbook

Written by Stefan on Wed 30 November 2022. Posted in Blog.

In this blog post I'm showing how to get a Virtual Machine, defined in an Ansible inventory file, into the NetBox DCIM (Data Center Information Management) tool.

NetFlow with Elastic-Stack

Written by Stefan on Tue 02 August 2022. Posted in Blog.

This blog post shows how to setup a NetFlow collector with Elastic-Stack, Fleet and Elastic-Agent. NetFlow data is sent by a Cisco ASA Firewall cluster.

Technischer Schutz und Prozesse bei Datenlecks

Written by Stefan on Sun 24 July 2022. Posted in Blog.

In diesem Blog-Post beschreibe ich meine technischen Schutzmaßnahmen (Email) und Prozesse, wenn ich von einem Datenleck betroffen bin.

Cisco Wireless Intrusion Detection Events to Elastic-Stack

Written by Stefan on Tue 07 June 2022. Posted in Blog.

In this blog post I'm showing how to get Wireless Intrusion Detection Events from Cisco's WIDS included in Cisco's Wireless Controllers into an Elastic-Stack.

802.1X Switch port is amber when only IP Phone is connected

Written by Stefan on Sat 21 May 2022. Posted in Blog.

When 802.1X (wired) is configured on a 3750G switch, the port LED is amber when only an IP Phone is connected (mab). When connecting on the IP Phone a downstream device like a laptop (dot1x), the port LED goes to green.

Login-Block (DoS and Dict-Attack Protection) in Cisco IOS

Written by Stefan on Thu 21 April 2022. Posted in Blog.

Cisco offers a method to protect against DoS (Denial-of-Service) and Dictionary attacks for IOS devices called Login-Block.

Update Schneider-APCUPS firmware with Linux

Written by Stefan on Mon 14 March 2022. Posted in Blog.

In this blog post I'm showing how to update a Schneider-APC UPS with Linux.

Mapping of IP addresses blocked by Russia

Written by Stefan on Sun 06 March 2022. Modified on Thu 28 July 2022. Posted in Blog.

Mapping of IP addresses blocked by Russia

New fiber optics cables for my network

Written by Stefan on Mon 28 February 2022. Posted in Blog.

New fiber optics cables for my network. OM4, LC/LC connectors, 4x1 Gigabit link.

Synology DiskStation to Cisco Core Switch redundant setup with LACP

Written by Stefan on Wed 16 February 2022. Posted in Blog.

Configuration of LCAP (Link Aggregation Control Protocol) for Synology DiskStation and Cisco Switch.

Schneider-APCUPS battery replacement

Written by Stefan on Thu 03 February 2022. Posted in Blog.

Small how-to about Schneider-APC UPS battery replacement and setting replacement date in Network management card.

Elastic-Stack for network engineers (Initial setup)

Written by Stefan on Sat 02 October 2021. Posted in Blog.

Switching from traditional log monitoring to Elastic-Stack is like switching from a horse-drawn carriage to the Falcon 9 rocket. Join the journey!

Cisco SSM On-Prem Upgrade procedure

Written by Stefan on Thu 16 September 2021. Posted in Blog.

This is another blog post for Cisco SSM On-Prem server where I'm showing the upgrade process.

Cisco ISE admin password lifecycle and reset

Written by Stefan on Mon 13 September 2021. Posted in Blog.

Quick notes about Cisco Identity Services Engine password lifetime and admin password reset.

Cisco SSM On-Prem password recovery procedure

Written by Stefan on Wed 08 September 2021. Posted in Blog.

For a Cisco Smart Software Manager Test Drive installation I used the older version 8-202010 and I wanted to perform an upgrade to the latest version 8-202108. And of course it is a test drive, I did not save or wrote down the password :). In this document I'm describing how to perform a password recovery for a Cisco SSM On-Prem installation.

Upgrading Netbox to Version 3.0

Written by Stefan on Tue 31 August 2021. Posted in Blog.

Yesterday, the version v3.0 of Netbox was released. Modernized WebUI and Off-canvas sidebar. My first impression: Version v3.0 is awesome! Note: Version v3.0.1 was released on 2021-09-01.

Gitlab AD-LDAP Integration

Written by Stefan on Thu 26 August 2021. Posted in Blog.

In this blog post I'm showing how to integrate GitLab Server with a Samba-based Active Directory.

Troubleshooting SFP transceivers and Packet captures

Written by Stefan on Sat 03 July 2021. Posted in Blog.

In an older blog post I was writing about "Useful Cisco Commands for Troubleshooting cable problems". In this blog post I'm showing an additional, useful commands for Fiber Optics troubleshooting and packet capturing on Cisco switches.

Cisco WLC - No secured WebUI after failover switching

Written by Stefan on Thu 10 June 2021. Posted in Blog.

Cisco WLC 3504 secured WebUI is not working on Secondary Unit in a failover (SSO) setup. When switched back to the Primary Unit, the secured WebUI is working again. Troubleshooting and solution of this strange behavior.

Some security settings for Apache Web Server

Written by Stefan on Sun 06 June 2021. Posted in Blog.

I'm showing in this blog post some security settings for the Apache web server including disabling of Directory Browsing, Server Signature and Server Token.

Integration of Nextbox UI Topology Viewer in Netbox

Written by Stefan on Sun 16 May 2021. Posted in Blog.

In this blog post I'm showing how to integrate NextBox UI Plugin into my Netbox installation. NextBox UI Plugin is a topology visualization plugin which is based on Cisco's neXt toolkit.

City of Erbach is ending their partnership with Odenwald gegen rechts

Written by Stefan on Sat 15 May 2021. Posted in Blog.

City of Erbach is ending their partnership with "Odenwald gegen rechts" ("Odenwald against Right")

WiFicalypse 2021

Written by Stefan on Wed 12 May 2021. Posted in Blog.

WiFicalypse 2021, FragAttacks. Design and Implementation flaws in WiFi.

Small Python script to quick test DMARCDKIM and SPF records

Written by Stefan on Wed 05 May 2021. Posted in Blog.

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.

Netbox Active Directory/LDAP Integration

Written by Stefan on Fri 30 April 2021. Posted in Blog.

In my newest blog post I show how to setup Netbox with Active Directory as backend for users and groups.

Concept for DNS security with Bind9, Pi-hole and OpenDNS

Written by Stefan on Sun 18 April 2021. Posted in Blog.

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.

Blocking of Google Chrome FLoC

Written by Stefan on Mon 12 April 2021. Posted in Blog.

Blocking of Google Chrome FLoC (Federated Learning of Cohorts) on my web server

Weeks of the data leaks

Written by Stefan on Sun 11 April 2021. Posted in Blog.

Weeks of the data leaks and my approach after data leaks or breaches

Debian Unattended upgrades

Written by Stefan on Tue 06 April 2021. Posted in Blog.

Automatically install security-related upgrades on Debian Linux with unattended-upgrades

Fritzbox rack mounted

Written by Stefan on Wed 10 March 2021. Posted in Blog.

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 ;)

Check in of configuration files to a Gitlab server

Written by Stefan on Mon 08 March 2021. Posted in blog.

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

Low Level Device functions for backup with Netbox and Gitlab

Written by Stefan on Wed 03 March 2021. Posted in blog.

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.

Cisco configuration backup with Netbox and Gitlab

Written by Stefan on Mon 01 March 2021. Posted in blog.

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.

Fritzbox on redundant ASA Firewall

Written by Stefan on Thu 18 February 2021. Posted in Blog.

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 Test Drive

Written by Stefan on Mon 01 February 2021. Posted in Blog.

Cisco Smart Software Manager (SSM) On-Prem Test Drive installation, Virtual Machine setup and first steps in the Web UI

Upgrading memory on my XCP-NG hypervisors

Written by Stefan on Thu 12 November 2020. Posted in blog.

Upgrading memory on my XCP-NG hypervisor servers from 32Gb RAM to 64Gb RAM

Looking up asset tags in Snipe-IT with QR code

Written by Stefan on Sat 24 October 2020. Posted in blog.

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

Written by Stefan on Fri 16 October 2020. Posted in blog.

Creating QR code for wireless networks and a MeCard with Linux

Learning material for network automation

Written by Stefan on Tue 29 September 2020. Posted in blog.

Learning material for network automation with books, videos, podcasts, courses and API, libraries and tools

Installing Gitlab on Debian Linux

Written by Stefan on Sat 05 September 2020. Posted in blog.

Installing Gitlab on Debian Linux and connecting with Atom editor

Netbox Login failed after upgrade to version 2.9.0

Written by Stefan on Sun 23 August 2020. Posted in blog.

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)

Netbox Custom Links for Snipe-IT and LibreNMS

Written by Stefan on Fri 14 August 2020. Posted in blog.

Python scripts with API calls as Custom Links for Snipe-IT and LibreNMS.

Custom links in Netbox for Snipe-IT Asset Management

Written by Stefan on Sat 01 August 2020. Posted in blog.

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)

Written by Stefan on Sat 18 July 2020. Posted in blog.

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

Upgrading XCP-NG Hypervisor from version 7.6 to version 8.1

Written by Stefan on Sun 14 June 2020. Posted in blog.

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.

Netbox: New installation (2.8.5) and NAPALM plus LibreNMS API integration

Written by Stefan on Thu 11 June 2020. Posted in blog.

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.

Netbox: New installation (2.8.5) and cabling and assigning IP addresses

Written by Stefan on Sun 07 June 2020. Posted in blog.

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.

Netbox: New installation (2.8.5) and filling up an empty rack

Written by Stefan on Mon 01 June 2020. Posted in blog.

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).

Why 2.4 GHz WiFi is bad

Written by Stefan on Thu 28 May 2020. Posted in blog.

Cisco CleanAir quality report for 2.4GHz WiFi in my area

Useful Cisco Commands for Troubleshooting cable problems

Written by Stefan on Fri 21 February 2020. Posted in blog.

Useful Cisco Commands for Troubleshooting problematic cabling (Cat.x and Fiber optics).

Simple High Availability with CARP

Written by Stefan on Wed 05 February 2020. Posted in blog.

Simple High Availability with CARP (Common Address Redundancy Protocol)

Cisco Live 2020 Barcelona

Written by Stefan on Fri 31 January 2020. Posted in blog.

Cisco Live 2020 Barcelona, Day #1 - A cat and mouse Game, Day #2 - Attack Kill Chain and Packet Capturing, Day #3 - About Garlic and Onions and Industrial automation, Day #4 - Catalyst 9000 Access Switching Architecture and Resolving Network Faults Faster through Automating Entire Fault Management, Day #5 - SD-WAN, deployment strategies, managing and monitoring

Simple load balancing with Apache proxy_balancer

Written by Stefan on Tue 17 December 2019. Posted in Blog.

Simple load balancing with Apache proxy_balancer and testing with siege

Replacing faulty memory for Cisco ASA-5520

Written by Stefan on Sat 26 October 2019. Posted in Blog.

Replacing faulty memory for Cisco ASA-5520, checking memory and failover

NetBox, Snipe-It and LibreNMS

Written by Stefan on Sat 28 September 2019. Posted in Blog.

NetBox, Snipe-It and LibreNMS: Three tools for Data Center Information Management (DCIM), IT Asset Management (ITAM) and Network Monitoring System (NMS).