documented NAC's OCSP service for DEP and outlined limitation of appl…

…y… (#272) * documented NAC's OCSP service for DEP and outlied limitation of applying SINGLE NAT * Commit changes made by code formatters * Update README.md * Added styling to the titles * Commit changes made by code formatters --------- Co-authored-by: Jahir <[email protected]> Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com> Co-authored-by: Sandhya Buddharaju <[email protected]>
ministryofjustice · Apr 5, 2024 · d4e5895 · d4e5895
1 parent 32ed1f3
commit d4e5895
Show file tree

Hide file tree

Showing 3 changed files with 20 additions and 0 deletions.
diff --git a/README.md b/README.md
@@ -32,6 +32,7 @@ This repository defines the **system infrastructure only**. Specific components
 - [Vertically scaling the Read Replica](documentation/database-upgrade.md)
 - [Setup Performance Testing](documentation/performance_testing.md)
 - [Database Access - dump with bastion](documentation/rds-bastion.md)
+- [DEP OCSP Service Overview](documentation/ocsp-over-internet.md)
 
 ## CI/CD
 

diff --git a/documentation/azure-images/ocsp-nat.png b/documentation/azure-images/ocsp-nat.png
diff --git a/documentation/ocsp-over-internet.md b/documentation/ocsp-over-internet.md
@@ -0,0 +1,19 @@
+- ### OCSP
+
+  NAC currently required to work with OCSP endpoint within internal subnet issued by internal CA and no requirement to send traffic over the internet, however, as a part of DEP(Digital Education Project) this service needed to onboard external CA which required NAC to send OCSP traffic over the internet.
+
+- As a part of this we needed to provide a static set of IPS in order for the supplier to ALLOW-LIST NAC on their service.
+
+Currently, NAC's cluster tasks are auto assigned with a public IP and these are subjected to change everytime service gets re-deployed.
+In order to solve this problem a SOURCE-NAT was configured using AWS NAT Gateway for traffic bound to DEP OCSP IP range.
+
+#### High level solution outlining DEP OCSP traffic
+
+![High level solution outlining DEP OCSP traffic
+](../documentation/azure-images/ocsp-nat.png)
+
+- ### Limitation
+
+  As per the best practice NAT should have been deployed in to multi-az, however, due to the limitation on the available subnet and CIDR limitation assigned to this VPC, it was not possible to deploy NAT across all availability zones without significant refactoring of the existing VPC.
+
+- In the event of an availability zone failures NAC DEP service will be degraded until AWS brings back the service.This has been raised as risk.