I am using few AWS Lambda functions, which are sitting inside private subnets,
These private subnets have VPC endpoints configured for the services for which the functions need access to,
The current setup does not use a NAT gateway, therefore all the traffic from the functions is going through the VPC endpoints.
I now have a use-case where we need to use a NAT gateway,
But would enabling NAT mean that the Functions would no longer use the VPC endpoints for external service access, and instead use the NAT?
I think this works as follows. For:
Gateway endpoints (S3, DynamoDB)
Routes to them are added automatically to our route tables when you create them. Docs says:
If you have an existing route in your route table for all internet
traffic (0.0.0.0/0) that points to an internet gateway, the endpoint
route takes precedence for all traffic destined for the service,
because the IP address range for the service is more specific than
0.0.0.0/0. All other internet traffic goes to your internet gateway, including traffic that's destined for the service in other Regions.
Interface VPC Endpoints
They work by modifying IP addresses in a DNS of a service. The IP address will be private addresses of the endpoint interfaces. Docs says:
The hosted zone contains a record set for the default DNS name for the
service (for example, ec2.us-east-1.amazonaws.com) that resolves to
the private IP addresses of the endpoint network interfaces in your
VPC. This enables you to make requests to the service using its
default DNS hostname instead of the endpoint-specific DNS hostnames.
To use private DNS, you must set the following VPC attributes to true:
enableDnsHostnames and enableDnsSupport.
Conclusion
So in both cases, priority is given to the interfaces, not the internet. I recommend checking the links provided. They have more info with examples to double check my conclusions.
VPC Endpoints or NAT Gateway?
AWS services like EC2, RDS, Lambda, and ElastiCache come with an Elastic Network Interface (ENI), which enables communication from within your VPCs via Private Endpoints. However, many AWS services provide a REST API, available via the Internet only. A few examples: S3, DynamoDB, CloudWatch, SQS, and Kinesis.
There are three options to make these services accessible from private subnets:
A VPC Endpoint type: Gateway Endpoints is free of charge, but are only available for S3 and DynamoDB.
A VPC Endpoint type: Interface Endpoint costs $7.20 per month and AZ plus $0.01 per GB and is available for most AWS services.
A NAT Gateway can be used to access AWS services or any other services with a public API. Costs are $32.40 per month and AZ plus $0.045 per GB.
Keep the following rules of thumb in mind when designing your network architecture.
Adding Gateway Endpoints for S3 and DynamoDB should be your default option.
Do you need to access non-AWS resources via the Internet, add a NAT Gateway. Do the math if traffic to AWS services justifies additional Interface Endpoints.
Are you only accessing AWS services from the private subnets? No more than four different services? Use Interface Endpoints. Otherwise, do the math to calculate costs for Interface Endpoints and NAT Gateway.
Ref Link: https://cloudonaut.io/advanved-aws-networking-pitfalls-that-you-should-avoid/
Related
We have 10 instances which we deployed the app using the AWS ECS and ELB
Due to security reasons the API allows request only through specific IP whitelisted IP addresses.
So we are planning to pass the request through the proxy
How to route an API request go through a proxy
We are using nginx
Any specific way to route an API request go through a proxy will be helful
You won't need NGINX as a proxy for this use-case, I'd propose to consider looking into using AWS NAT Gateways. NAT Gateway is a highly available AWS managed service that makes it easy to connect to the Internet from instances within a private subnet in an Amazon Virtual Private Cloud (Amazon VPC). Its the perfect place to provide a static IP to all your subnet's outbound traffic.
In order to provide a NAT Gateway with static IP (Elastic IP) for your cluster's outbound traffic. This will allow your different tasks running inside your ECS cluster's private subnets to look like a single requesting entity from an outsider's POV (in your case, the 3rd party API is the outsider). To achieve this, you will have to:
Create 2 route tables (1 for private subnets, 1 for public subnets)
Internet gateway on the public subnet
Elastic IP address
Create a NAT Gateway and attach the elastic IP to it (This will be the IP whitelisted to the 3rd party API)
Ensure that all your tasks are running inside private subnets of the VPC
Add a rule in your route table for your private subnets that redirects outbound 0.0.0.0/0 to the NAT Gateway.
Add a rule in your route table for your public subnets that redirects outbound traffic 0.0.0.0/0 to the internet gateway.
You should consider using NAT Gateway instead. I am assuming you already would have all your containers in a VPC, so you can create a new NAT Gateway within this VPC itself.
You can refer to articles attached below to do this:
https://docs.aws.amazon.com/appstream2/latest/developerguide/add-nat-gateway-existing-vpc.html
https://docs.aws.amazon.com/vpc/latest/userguide/vpc-nat-gateway.html
Note: NAT Gateways have price associated with them.
If needed, you can use the elastic IP provided by NAT Gateways on your lambdas as well.
What is the difference between Private Link and VPC endpoint? As per the documentation it seems like VPC endpoint is a gateway to access AWS services without exposing the data to internet. But the definition about AWS private link also looks similar.
Reference Link:
https://docs.aws.amazon.com/vpc/latest/userguide/endpoint-services-overview.html
Does Private Link is the superset of VPC endpoint?
It would be really helpful if anyone provides the difference between these two with examples!
Thanks in Advance!
AWS defines them as:
VPC endpoint — The entry point in your VPC that enables you to connect privately to a service.
AWS PrivateLink — A technology that provides private connectivity between VPCs and services.
So PrivateLink is technology allowing you to privately (without Internet) access services in VPCs. These services can be your own, or provided by AWS.
Let's say that you've developed some application and you are hosting it in your VPC. You would like to enable access to this application to services in other VPCs and other AWS users/accounts. But you don't want to setup any VPC peering nor use Internet for that. This is where PrivateLink can be used. Using PrivateLink you can create your own VPC endpoint services which will enable other services to use your application.
In the above scenario, VPC interface endpoint is a resource that users of your application would have to create in their VPCs to connect to your application. This is same as when you create VPC interface endpoint to access AWS provided services privately (no Internet), such as Lambda, KMS or SMS.
There are also Gateway VPC endpoints which is older technology, replaced by PrivateLink. Gateways can only be used to access S3 and DynamoDB, nothing else.
To sum up, PrivateLink is general technology which can be used by you or AWS to allow private access to internal services. VPC interface endpoint is a resource that the users of such VPC services create in their own VPCs to interact with them.
Suppose there is a website xyz.com that I am hosting in a bunch of Ec2 instances, exposed to the outside world thru a Network load balancer.
Now, a client who has his/her own AWS account, wants to access this xyz.com from an Ec2 running in their aws account.
One approach is to go thru the Internet.
However the client wants to avoid the internet route.
He/she wants to use the AWS backbone to reach xyz.com.
The technology that enables that, is AWS Private link.
(note that if you search for Private Link in the AWS services, there will be none.
You will get "End point services" as the closest hit)
So, this is how to route traffic through the AWS backbone:
I, the owner of xyz.com, will create a VPC End Point Service (NOTE the keyword Service here)
The VPC End point service will point to my Network load balancer.
I will then give my VPC End point service name to the client.
The client will create a VPC End Point (NOTE.. this is different from #1).
While creating it, the client will specify the VPC End Point Service name (from #1) that he got from me.
I can choose to be prompted to accept the connection from the client to my VPC End point service.
As soon as I accept it, then the client can reach xyz.com from his/her EC2 instance.
There is no Internet, no direct connect or VPN.. this simply works; and its secure.
And which technology enabled it.. AWS Private link !!!
PRIVATE LINK IS THE ONLY TECHNOLOGY THAT ALLOWS 2 VPCS TO CONNECT THAT HAVE OVERLAPPING CIDR RANGES.
A useful way in understanding differences is in how they technically connect private resources to public services.
Gateway Endpoints route traffic by adding prefix lists within a VPC route table which targets the Gateway endpoint. It is a logical gateway object similar to a Internet Gateway.
In contrast, an Interface Endpoint uses Privatelink to inject into a VPC at the subnet level, via an Elastic Network Interface (ENI), giving network interface functionality, and therefore, DNS and private IP addressing as a means to connect to AWS public services, rather than simply being routed to it.
The differences in connections offer differing advantages and disadvantages (availability, resiliency, access, scalability, and etc), which then dictates how best to connect private resources to public services.
Privatelink is simply a very much abstracted technology to allow a more simplified connection by using DNS. The following AWS re:Invent offers a great overview of Privatelink: https://www.youtube.com/watch?v=abOFqytVqBU
As you correctly mentioned in the question that both VPC endpoint and AWS private link do not expose to internet. On AWS console under VPC, there is a clear option available to create an endpoint. But there is no option/label to create AWS private link. Actually, there is one more option/label called endpoint service. Creating endpoint service is one way to establish AWS private link. At one side of this AWS private link is your endpoint service and at the other side is your endpoint itself. And interestingly we create both these sides in two different VPCs. In other words, you are connecting two VPCs with this private link (instead of using internet or VPC peering).
understand like,
VPC1 got endpoint service ----> private link -----> VPC2 got endpoint
Here endpoint service side is service provider while endpoint is service consumer. So when you have some service (may be some application or s/w) that you think other VPC endpoints can consume you create endpoint service at your end and consumers will create endpoints at there end. When consumers create endpoints at their end they have to give/select your service name and thus private link will be established with your service.
Ultimately you can have multiple consumers of your service just like one to many relationship.
When I configure an AWS Gateway VPC endpoint, a route table entry is created that points to the Gateway. Here, Gateway can be thought of performing the routing to AWS service (over private network).
However, for an AWS Inteface VPC endpoint, all that is visible is a Network interface that has a private IP address of the subnet. By default, a private IP can send traffic within the subnet or entire VPC provided Security Group and NACL allows the traffic. & it appears in this case there is no Route table entry to a Gateway or a Router for allowing traffic outside VPC.
How / Where is the interface routing the traffic to i.e. How does traffic leave the customer VPC?
Of course I understand that the traffic finally reaches the intended AWS service over private network but here I am trying to find out where is the Gateway or Router? Does AWS hide this implementation?
I cannot get my head around the fact that a simple Network Interface can accept traffic and route it to a service all by itself i.e. performing routing by itself? Clearly, in this case the traffic appears not flowing through the VPC router or another Gateway device.
I am aware this might be an AWS confidential implementation but any thoughts / idea on how they might have designed this feature?
It doesn't provide routing at all, by default a VPC interface endpoint when created will create an ENI per subnet in the VPC for you. It will also provide you a DNS name per each AZ and a global name that you can use within your applications.
In addition it supports the ability to have the AWS service domain name for the VPC interface endpoint be resolvable to the private IPs of the endpoint. As long as your VPC has DNS enabled it will first check the VPC private DNS resolver and then resolve it to the private IP rather than the public one.
This is done by adding an additional private hosted zone to your VPC which resolves service domains in your region such as ec2.us-east-1.amazonaws.com.
From the AWS side this is just an ENI created in your AWS VPC that is connected to one of AWS internal VPCs. It's actually possible to implement this for your own services too to share with another organisations VPCs, this is implemented using AWS PrivateLink.
For more information take a look at the Private DNS for interface endpoints page.
I have Public and Pvt Subnets in my VPC. I have some services running on EC2 in Pvt subnet, that needs to be accessed by external/mobile resources. How do I do this- is VPCLink and NLB the way to do it, or any other way, create some access point in Public subnet (??). Lambda seems to be the answer (for almost everything in AWS now) - not sure even how that access works for resources in Pvt Subnet.
Also the same Pvt Subnet has access external resources (outside of AWS) - how do I do this using the API Gateway?
Not quite understanding how the API-Gateway (and Lambda) is situated vis-a-vis - VPC and subnets- and how the network access control functions- can they access Pvt subnets directly or not. The documentation is somewhat silent on this, only talks about IAM - if someone can explain this. Found this on Lambda: AWS Lambda: How to setup a NAT gateway for a lambda function with VPC access.
The documentation says "API Gateway allows you to securely connect ... publicly addressable web services hosted inside or outside of AWS". My resources in Pvt subnet are not publicly addressable - I suppose.
Thanks
Are the services you have running on EC2 offering an API? API Gateway is meant to proxy API requests. It's commonly used in conjunction with Lambda to allow Lambda functions to process HTTP requests. An API Gateway is not necessary for your service. You can simply use an Application Load Balancer (ALB) or an Elastic Load Balancer (ELB). They can reside on a public subnet while your service remains in the private subnet. You can use security groups and VPC routing tables to allow communication from your public ALB/ELB to your private EC2 service.
With Ben’s help here is the answer
Introducing Amazon API Gateway Private Endpoints
Inbound: Accessing services hosted in Private Subnet via API Gateway
Endpoint integrations inside a private VPC. With this capability, you can now have your backend running on EC2 be private inside your VPC without the need for a publicly accessible IP address or load balancer.
So essentially API Gateway can access published endpoints, even in Private Subnets.
OutBound: Accessing externally hosted services from Private Subnet via API Gateway
API Gateway private endpoints are made possible via AWS PrivateLink interface VPC endpoints. Interface endpoints work by creating elastic network interfaces in subnets that you define inside your VPC. Those network interfaces then provide access to services running in other VPCs, or to AWS services such as API Gateway. When configuring your interface endpoints, you specify which service traffic should go through them. When using private DNS, all traffic to that service is directed to the interface endpoint instead of through a default route, such as through a NAT gateway or public IP address.
So you simply need to create a VPC endpoint in the Pvt Subnet for the API Gateway.
I have one VPC where i configured NAT Gateway. Another VPC(s) do not have any "public subnet" nor IGW. I would like to share single NAT Gateway among many VPCs.
I tried to configure Routing table but it does not allow to specify NAT Gateway from different VPC.
As posible solution, I installed http/s proxy in VPC with IGW and configured proxy settings on every instance in different VPC. It worked, but I would like use NAT Gateway due to easier management.
Is it possible to make this kind of configuration at AWS?
There are few VPCs and I do not want to add NAT Gateway to each VPC.
Zdenko
You can't share a NAT Gateway among multiple VPCs.
To access a resource in another VPC without crossing over the Internet and back requires VPC peering or another type of VPC-to-VPC VPN, and these arrangements do not allow transit traffic, for very good reasons. Hence:
You cannot route traffic to a NAT gateway through a VPC peering connection, a VPN connection, or AWS Direct Connect. A NAT gateway cannot be used by resources on the other side of these connections.
http://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/vpc-nat-gateway.html#nat-gateway-other-services
The instances in the originating VPC are, by definition, "on the other side of" one of the listed interconnection arrangements.
AWS Transit Gateway now provides an option to do what you wish, although you will want to consider the costs involved -- there are hourly and data charges. There is a reference architecture published in which multiple VPCs share a NAT gateway without allowing traffic between the VPCs:
https://aws.amazon.com/blogs/networking-and-content-delivery/creating-a-single-internet-exit-point-from-multiple-vpcs-using-aws-transit-gateway/
You basically have 3 options
connect to a shared VPC (typically in a shared "network" account) that holds the NAT via VPC peering. No additional costs for the VPC peering, but cumbersome to setup if you have a lot of accounts
same, but using Transit Gateway. A Peering Attachment is almost the same cost as a single NAT, so this will only save costs if you use multiple NAT gateways to have a high bandwidth
Setup a shared VPC (e.g. in an infrastructure account that holds the NAT. Then share private subnets via AWS resource manager (RAM) to the VPCs that need outgoing access. This has the additional benefit you have a single place where you allocate VPC IP ranges and not every account needs to bother with setting up the full VPC. More details in AWS VPC sharing best practices. This setup avoids both the Transit Gateway costs and the burden of setting up VPC peering. But needs more careful planning to keep things isolated (and likely not everything in the same VPC)