Welcome to Ieuan ⚪ Net

Work

hi@ieuan.net (Ieuan Jenkins) — Thu, 05 Jun 2025 14:30:51 +0100

I work with computers.

At the moment, this is via jensys.uk.

You can also view my CV here: ieuan.net/cv.

You can find me in a few other places:

Offline Device-to-Device File Sharing

hi@ieuan.net (Ieuan Jenkins) — Wed, 04 Jun 2025 00:00:00 +0000

I was recently travelling abroad and needed to transfer a large file from my Android phone to my wife’s iPhone. Waiting in the security queue in the airport with a patchy internet connection, no computer or USB cable, I was stumped. I was sure there were plenty of shady devs on the Play Store queuing up to offer file-sharing apps crammed full of ads and other abusive behaviour or worse… but I hoped to avoid all that.

Shelves

hi@ieuan.net (Ieuan Jenkins) — Sat, 12 Apr 2025 00:00:00 +0000

The other day I was making some shelves for our kitchen and wanted to visualise them before I drilled any holes.

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Iso sketch of kitchen shelves

Had a little flashback to hours spent hand-drawing flanges on isometric paper in engineering lessons.

Taranaki

hi@ieuan.net (Ieuan Jenkins) — Sat, 24 Sep 2022 00:00:00 +0000

Taranaki Maunga is simply phenomenal.

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Copyright: Gully, John, 1819-1888 :Mount Egmont or Taranaki / John Gully, 1875. Dunedin, Marcus Ward, 1877.. Gully, John, 1819-1888 :New Zealand scenery chomolithographed after original water-color drawings by John Gully with descriptive letterpress by Dr Julius von Haast. Dunedin, Henry Wise & Company ; London Marcus Ward & Co., 1877. Ref: PUBL-0010-13. Alexander Turnbull Library, Wellington, New Zealand.

Date: 1875-01-01

Gully, John, 1819-1888 :Mount Egmont or Taranaki / John Gully, 1875. Dunedin, Marcus Ward, 1877.. Gully, John, 1819-1888 :New Zealand scenery chomolithographed after original water-color drawings by John Gully with descriptive letterpress by Dr Julius von Haast. Dunedin, Henry Wise & Company ; London Marcus Ward & Co., 1877. Ref: PUBL-0010-13. Alexander Turnbull Library, Wellington, New Zealand.

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Camera Model: Canon EOS R6

Date: 2023-03-05

F-number: ƒ/4.000000 | Focal Length: 64mm

Exposure Time: 1/125 | ISO: 100

View of Taranaki Maunga looking across Lake Mangamahoe

The Te Papa-Kura-o-Taranaki (national park) surrounding it was defined as a 6-mile radius from the cone of the maunga, making a near complete circle of native bush. If you fly past (or even view it from space), the park boundary appears as the world’s biggest crop circle of deep green forest.

Bins of Maraetai

hi@ieuan.net (Ieuan Jenkins) — Fri, 24 Dec 2021 00:00:00 +0000

The hills in Maraetai are so steep
That folks here are prone to cheat
When collecting their bin
They make a real din
Towing with ute ‘stead of feet.

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Camera Model: iPhone 12 Pro

Date: 2021-12-24

F-number: ƒ/1.6 | Focal Length: 4mm

Exposure Time: 1/121 | ISO: 64

Birds of Aotearoa

hi@ieuan.net (Ieuan Jenkins) — Sun, 24 Oct 2021 00:00:00 +0000

I’ve been fortunate to have come across quite a handful in the past few years. Plenty on the to-spot list still!

Incredible statistic: All our frogs and reptiles, more than 90 per cent of our insects, about 80 per cent of our vascular plants (plants other than mosses, liverworts, and hornworts), and a quarter of our bird species are found only in New Zealand¹.

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Camera Model: Canon EOS 400D DIGITAL

Date: 2021-10-23

F-number: ƒ/5.6 | Focal Length: 50mm

Exposure Time: 1/500 | ISO: 100

Gannets nesting on the cliffs at Muriwai

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Camera Model: Canon EOS R6

Date: 2023-02-05

F-number: ƒ/6.3 | Focal Length: 300mm

Exposure Time: 1/320 | ISO: 160

Kererū hiding in a Kōwhai on Tiritiri Matangi

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Camera Model: Canon EOS R6

Date: 2022-10-24

F-number: ƒ/7.1 | Focal Length: 300mm

Exposure Time: 1/500 | ISO: 100

Two wary kōtare on a branch on Motutapu

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Camera Model: Canon EOS R6

Date: 2023-02-05

F-number: ƒ/6.3 | Focal Length: 300mm

Exposure Time: 1/320 | ISO: 400

Black sand of Muriwai beach

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Camera Model: Canon EOS R6

Date: 2022-07-17

F-number: ƒ/7.1 | Focal Length: 70mm

Exposure Time: 1/500 | ISO: 100

Piwakawaka chasing me through Duder park

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Camera Model: Canon EOS R6

Date: 2023-03-18

F-number: ƒ/2.8 | Focal Length: 70mm

Exposure Time: 1/80 | ISO: 800

Toutouwai in the Kaimanawa mountains

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Camera Model: Canon EOS R6

Date: 2023-02-05

F-number: ƒ/5.000000 | Focal Length: 190mm

Exposure Time: 1/250 | ISO: 1600

Takahē scratching for food on Tiritiri Matangi

Archive.org, 2023: Ministry for the Environment: Biodiversity ↩︎

Ephemeral Port Exhaustion in Kubernetes

hi@ieuan.net (Ieuan Jenkins) — Sun, 04 Aug 2019 00:00:00 +0000

I recently ran into an interesting situation with a Kubernetes cluster running on the Google Cloud Platform behind a Network Address Translation (NAT) accessing a resource across the public internet.

A unique connection between two hosts is identified by a 5-tuple of the following which are stored in the translation table:

Protocol (TCP or UDP)
Source IP (NAT)
Source Port (NAT)
Destination IP
Destination Port

When data is sent through a NAT from a private network, it modifies the packet’s source IP address and port to it’s own public IP and random port and stores a mapping in its translation table. When the remote server responds, the packet is returned to the NAT’s public IP address and port and the NAT translation table allows it to look-up the original connect to modify the packet again and replace the original private IP and port.

PowerShell for a Quick and Dirty Load Test

hi@ieuan.net (Ieuan Jenkins) — Mon, 04 Mar 2019 00:00:00 +0000

I needed a quick way to run a simple load test on an air-gapped remote server, where it wasn’t possible to install regular load-testing tools. In a Windows Server environment, PowerShell comes built-in so I thought I’d see how much mileage I can get out of it.

Measure a HTTP request #

$url = 'https://target-server/'
Measure-Command { Invoke-RestMethod $url }

Gives me some basic timings of the request (remembering that this includes stuff like client processing, network latency and remote server time). Still handy for a rough “finger in the wind” of how fast a server gives a response:

Hello World

hi@ieuan.net (Ieuan Jenkins) — Sat, 12 May 2012 00:00:00 +0000

I am an Electronic Engineering(BEng, Hons) graduate from University College, University of Durham currently living and working in London.