Category: Linux

Fixing a dead 40Gbps Celestica D2060 network switch

I have had a dead Celestica D2060 network switch laying in my garage for a while and decided to finally attempt to fix it. D2060 is a Broadcom Trident2 BCM56854A2 powered device offering 48x10G SFP+ and 6x40G QSFP+ ports, with an Intel Atom Rangeley C2558 based control plane – notorious for dying due to a CPU bug.

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Installing Ubuntu manually (from a running system)

Sometimes it can be useful to be able to manually install an Ubuntu system – either from an existing running system, or a live installation media environment. Fortunately this process is rather straightforward.

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Bird 1.6: The Unofficial Guide

We all know the lovely routing daemon called Bird. However, the official documentation can be a bit lacking and daunting. Here’s my collection of useful examples

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YUM/DNF ignores packages from a custom repository

Recently, I needed to compile a custom version of libvirt, repack it and insert it into my own repository. YUM/DNF was however ignoring my version and continued installing one from AppStream…

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Linux system as an IXP router

While it is possible to use a Linux based router in an internet exchange setting, there are some tweaks one has to make in order to not cause any trouble.

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DHCP server on a /32 subnet

How to force a DHCP server to hand over /32s, while running on a different /32 subnet.

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ECMP problems between two systems

Solving a tricky problem with ECMP between two machines, where one system refused to balance connections at random intervals.

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Retaking control of your network: Part 2

Computer networks are becoming increasingly complex with more and more devices connected each day. Gaining network visibility is absolutely crucial to ensure your traffic flows smoothly and transit costs are kept low. In this mini-series I will show you how to set-up sFlow sampling on Linux, aggregate the data and finally present it in flashy graphs.

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Retaking control of your network: Part 1

Computer networks are becoming increasingly complex with more and more devices connected each day. Gaining network visibility is absolutely crucial to ensure your traffic flows smoothly and transit costs are kept low. In this mini-series I will show you how to set-up sFlow sampling on Linux, aggregate the data and finally present it in flashy graphs.

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SSH jumping through multiple jump hosts

The standard OpenSSH SSH client accepts the argument -J to allow users to utilize a jump host/jump box.

What I recently discovered (and isn’t immediately obvious from the documentation) is that you can actually specify multiple jump hosts – separated by a comma – and the SSH client will jump through each single one in order to reach the target.

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