Category Archives: Admin

Bluecoat ProxySG and DNS using edns seem incompatible

Intro Imagine your DNS server had this behaviour when queried using dig: $ dig drjohnstechtalk.com @146.201.145.30 ; <<>> DiG 9.9.2-P2 <<>> drjohnstechtalk.com @10.201.145.30 ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: FORMERR, id: 48905 ;; flags: … Continue reading

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Use Raspberry Pi to explore mDNS

Intro I am confounded by the Bonjour field on my d-Link DCS-931L IP webcam. I should be able to use it to se my desired hostname, but it doesn’t take. Why? The details Having a Raspberry Pi on the same … Continue reading

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Tips for creating a PayPal Donate button for not-not-for-profits

Intro I am treating my blog as a public service, so I thought it would be appropriate to have a Donation link even though I have not incorporated as a 501c3 non-profit. Is it even possible? Can I keep my … Continue reading

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What I’m working on now: saving $69 a year on my certificate costs

Intro I recently turned off my GoDaddy web site certificate and implemented one that cost me nothing. This will save me $69 per year. I wrote up my experience in this article: Idea for free web server certificates: Let’s Encrypt … Continue reading

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drjohnstechtalk now uses HTTP Strict Transport Security, HSTS

Intro I was reading about a kind of amazingly thorough exploit which could be done using a Raspberry Pi zero. Physical access is required, but the scope of what this guy has figured out and put together is really amazing. … Continue reading

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Powershell winrm client error explained

Intro This particular Powershell error I came across yesterday is not well explained in other forums. I present the error and the explanation though not necessarily the solution. The details I recently received my new PC running Windows 8.1. On … Continue reading

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Who’s using the UK Ministry of Defence’s IP addresses?

Intro When I first came upon a spear phishing email a few months ago which originated from the UK’s Ministry of Defence I thought that was pretty queer. Like, how ironic that an invoice scam is coming from a Defense … Continue reading

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IP address wall of shame

Intro It can be very time-consuming to report bad actors on the Internet. The results are unpredictable and I suppose in some cases the situation could be worsened. Out of general frustration, I’ve decided to publicly list the worst offenders. … Continue reading

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The IT Detective Agency: the case of the mysterious reset

Intro An F5 BigIP load balancer equipped with web application firewall worked for everyone, except one app used by one customer. What was going wrong? Packet trace I always do a packet trace when there is nothing else to go … Continue reading

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Idea for free web server certificates: Let’s Encrypt

Intro I’ve written various articles about SSL. I just came across a way to get your certificates for free, letsencrypt.org. But their thing is to automate certificate management. I think you have to set up the whole automated certificate management … Continue reading

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