BGP Test Lab – Part 4 – Internal BGP (iBGP) – Three Router Configuration (Interior Routing Protocol)

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In the previous article we discovered that iBGP requires a topology and usage that ensures that our exchange of routes between routers is not stopped by the iBGP rule: “A route learned via iBGP must not be advertised to another iBGP peer.” We came across this problem in the previous article where although in normal operational the routes were being … Read more

BGP Test Lab – Part 3 – Internal BGP (iBGP) – Three Router Configuration (next-hop-self)

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We’ll continue to explore Internal BGP (iBGP) in this next part of our deployment. We are going to be deploying another route in the AS Blue 65001. Remember that eBGP is used between AS and iBGP is used within an AS. Be aware however, that this lab topology is flawed in terms of its configuration, but it shows up … Read more

AWS EC2 Instance SSM Send Command

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You can submit commands into an EC2 instance via SSM (Secure Systems Manager), rather than having to open SSH to the machine. From within an authenticated session using AWS CLI on your workstation machine, you can remotely send commands to be run within the instance itself. The commands will typically be run as “root” within … Read more

Microsoft Exchange 2016/2019 Replacing Certificate if Issuer and Subject Same as Old Certificate

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Here’s an interesting one I came across today, there exists a problem whereby replacing a certificate on a Microsoft Exchange 2016 or 2019 won’t work if the Issuer and Subject of the new certificate happen to be the same as the old certificate (you are trying to replace). You’d expect most likely that when you … Read more

Expired Microsoft Exchange 2016 Self Signed Certificate

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What to do when your self-signed certificate for Microsoft Exchange 2016 expires, Microsoft provide some good guidance about this: https://learn.microsoft.com/en-us/exchange/architecture/client-access/renew-certificates?view=exchserver-2019 You might see errors such as this when you’re trying to administer via PowerShell: You’ll have permissions so the error is a red herring, what is actually happening is you’re attempting to perform an operation … Read more

BGP Test Lab – Part 1 – Introduction and Basic Two Router Configuration

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The first part is a basic deployment of BGP between two routers (Router A and Router B) with a single point to point link. In this example, each router is within its own AS (Autonomous System). Therefore any routes exchanged between each AS are eBGP (external BGP) routes. Routes exchanged within an AS are known … Read more