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Linux Networking Systems Administration

A script to bring Cisco Switch VLAN data into phpIPAM

We have recently set up an IPAM at my workplace, the excellent phpIPAM – https://phpipam.net/ I went through our install and added all our subnets into the IPAM, but to make the data much more useful we wanted to have the VLAN information also: However, I didn’t want to go through by hand, adding each […]

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Linux Networking Uncategorized

How Websites Load – A deep dive into the IP network stack and how it is used to connect to a site

I’ve made a series of videos exploring the Internet Protocol Suite, and how it is used to make a connection to a website. It’s a deep dive into the stack, explaining all the way down to the ethernet frames that a computer sends on the local link.

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Linux Networking Systems Administration

A script to scan a network range and create Kea DHCP reservations for devices it finds

This script is very simple. It will scan a network range attached to the device it is run from, and will turn what it finds into a list of reservations for the Kea dhcp server – https://kea.readthedocs.io/ You run it something like this, giving it a network range to scan. Then network should be a […]

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Linux Networking Systems Administration

Notes from debugging OSPF between cisco devices and Linux FRR ospfd configs

When trying to find why my ospf configs were not sending the correct costing from Linux -> Cisco devices, I found some useful commands that I thought I would note down for future reference. Linux – Using vtysh My ospfd.conf looks something like this: You can see the costs on linux using the vtysh command: […]

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Linux Networking Systems Administration

Workaround for SSH error to Cisco switch from Ubuntu 20.04 – no matching key exchange method found

Trying to SSH to a Cisco switch from Ubuntu 20.04 you may get this error: This error is because Ubuntu 20.04 has disabled the SHA1-based key exchange methods after some attacks have been found on SHA1. To work around this issue for Cisco switches you can use the command line argument -oKexAlgorithms=+diffie-hellman-group1-sha1 like this: To […]

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Linux Networking Systems Administration

A script to connect to a Cisco switch and backup the running-config using Python3 and Paramiko

I have been trying to find a way to create a regular backup of my Cisco switch’s running-config, so I can store it in my normal backups. However, after searching online I was able to find some tools that were almost there, but nothing that was quite as flexible as I needed, so I wrote […]

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Linux Networking raspberrypi

Using a Raspberry Pi 2 as a Router + Configuring Raspbian for IPv6 with Aussie Broadband

I recently decided to move away from using my Wifi access point as a router, and instead use an old my Raspberry Pi 2 as my router. I had a few reasons for doing this: I wanted a more up-to-date device as my internet facing box. My Wifi AP hasn’t received any firmware updates in […]