Automating Security List Rule reviews in Oracle Cloud Infrastructure

If you’re running workloads in Oracle Cloud Infrastructure (OCI) then it’s likely you’ll be familiar with Virtual Cloud Network (VCN) resources such as Subnets, Route Tables, Gateways etc. These software defined components allow you to build networks in OCI for you to deploy and run your workloads.

Oracle has documentation that explains VCN access and security features which include things like Security Rules, Security Zones, Local and Network Firewalls, and IAM policies. Security rules are made up of Security Lists and Network Security Groups (NSG’s) and are a foundational element of every VCN and Subnet that you create. They define what traffic is allowed in and out of your subnets and what hosts can talk to one another. When you create a subnet a Security List is automatically created with some default rules:

Default Security List Ingress Rules
Default Security List Egress Rules

When it comes to implementing network access controls, you can use Security Lists, Network Security Groups or both. They are virtual firewall features that control traffic at the packet level. I’ll be covering Network Security Group reviews in a later post as I want to focus on Security Lists, specifically how you can easily review and validate rules to ensure they align with your workload, organisational, security and compliance requirements.

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Managing multiple Let’s Encrypt certificates with Oracle Cloud Infrastructure

In my previous post I explained how you can use Let’s Encrypt and Oracle Cloud Infrastructure (OCI) serverless functions to obtain a publicly signed SSL certificate, and automatically manage its renewal lifecycle. The solution works as expected; I have a Let’s Encrypt certificate for my website automatically renewing 30 days before expiry. If you haven’t read my previous post I’d recommend taking a look before following the setup outlined below as it covers how the solution works, and some prerequisites.

Having multiple workloads running in various OCI regions I started thinking about a more elegant way to provision certificates across multiple regions. Certificates stored in the certificate service are only available to resources in the same region and would have required a function to be deployed in each region, and for each SSL certificate required.

I’ve since updated the solution to address this requirement. It is now possible to provision certificates across multiple OCI regions using a single OCI Function application. I’ve also taken the opportunity to implement other features such as:

  • Loading a list of certificates you want to manage from a JSON file stored in Object Storage.
  • Adding support for wildcard SSL certificates.
  • Adding support for Subject Alternative Names (SAN) in addition to the CN name.
  • Adding support for the use of DNS zones and Vaults that reside in different regions to the OCI Function.

Adding support to specify which vault, and region to use for a given certificate ensures that workloads with strict cryptographic key material requirements can still benefit from this solution.

If you’ve already followed the instructions from my previous post, the solution will continue to work as described. The only limitation being that it’ll only work for a single certificate. By following the steps below you can easily upgrade to issuing multiple certificates. If you haven’t set anything up yet that’s also fine as I’ll be covering the full install again here.

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Let’s Encrypt serverless automation with Oracle Cloud Infrastructure

Let’s Encrypt made its debut back in late 2015. It is a free Certificate Authority provided by the Internet Security Research Group. The goal was to support the adoption of SSL / TLS to ensure the privacy of information sent over the public Internet. Let’s Encrypt is now serving over 2.5M certificates per day.

If you’re reading this it’s likely you’ve had to deal with SSL certificates before. It’s also likely some of you will have investigated an outage, only to find that an SSL certificate expired somewhere that no one knew about. Certificate discovery, management, and renewal can be time consuming and not much fun.

Cloud providers have made this job easier with the introduction of certificate services that are able to issue public Domain Validation (DV) certificates. Oracle Cloud Infrastructure (OCI) currently allows you to create private Certificate Authorities (CA’s), private Certificates, and private Certificate Authority bundles. Private certificate resources are used to secure communication across a private network, where certificates can be installed and trusted to enable secure communication.

But what about publicly signed certs for users connecting over the Internet? Using a private OCI certificate will result in a “certificate not trusted” error in your web browser; this is where Let’s Encrypt comes in. I’m going to show you how to run a completely automated serverless Let’s Encrypt solution in your OCI tenancy to install and automatically renew certificates that show as trusted in your web browser.

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