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)
Related
I read many posts about how to connect DynamoDB when using a lambda in VPC. They all talk about either I need to create VPC Endpoint and use it for Dynamo client configuration or I need to configure NAT gateway.
But, at the moment, in my current existing app, I don't use none of these. But, my lambda works ok. Only I see severe timeout when I execute benchmark tests which many people recommend using VPCE.
I just can't figure out how my lambda currently works (connect DDB and read/write there).
My lambda lives in VPC as I am also connecting Aurora Postgres.
In my account, I can't locate any single VPC endpoint nor NAT gateway. So, this just confuses me.
As I mentioned in my question, I re-confirmed that I can't locate either VPCE or NAT GW. I checked the correct region.
So, there is another case that, I believe, needs to be included as part of these documents or posting to avoid any confusion like this.
The scenario is that VPC can be connected to a TGW. Then, my VPC doesn't need to have the IGW/NAT to reach out to internet. All non local traffic will be routed to TGW and there it will be taken care of assuming there is IGW or NAT. They call it "Centralized outbound routing"
Centralized outbound routing to the internet using TGW
The following diagram shows the key components of the configuration for this scenario. You have applications in VPC A and VPC B that need outbound only internet access. You configure VPC C with a NAT gateway and an internet gateway. Connect all VPCs to a transit gateway. Configure routing so that outbound internet traffic from VPC A and VPC B traverses the transit gateway to VPC C. The NAT gateway in VPC C routes the traffic to the internet gateway
ap-east-1,us-west-2,eu-north-1 we have these different regions, and I want to communicate through intranet,may be need use VPC. Could you please tell me how to config vpc, route, and subnets?
You need to setup VPC peering between the two VPCs in different regions. With the peering,
Traffic always stays on the global AWS backbone, and never traverses the public internet, which reduces threats, such as common exploits, and DDoS attacks.
How to set it up is explained in detail in AWS documentation.
From the information presented, the best option in your case as Marcin suggested is to use VPC Peering. You need to bear in mind that you can't peer VPCes with overlapping VPC CIDRs
Just for completion, there is another option to cross-connect VPCes from different accounts and regions called Transit Gateway. In your case, as you'll need to set up Transit Gateway Peering between the regions it may be a bit too complex.
VPC Peering is a region specific service and so can join VPCs only within the same region.
If you want to establish communication without using public internet between VPCs across regions you may explore on "VPC Endpoint" and "VPC Endpoint Services" options. Please note some of these services are not free-tier eligible, in case you are experimenting.
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 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/
We have a Lambda function in an account and we would like to access an EC2 instance (via HTTP) in another VPC which has a public IP attached. I was wondering what would be the best way to perform this communication. I am new to Lambda and I just got to know of the VPC lambdas. Which CIDRs do I need to open on the Security Group on the EC2 instance? Can I have a specific set of public IPs being picked in the source VPC - this way I can whitelist that range in the SG?
Does VPC peering seem like an overhead for this case or the only possible solution?
It all Depends on your requirements.However, Peering those VPCs is the best way to have the traffic remaining in your trusted Private Subnets which are located in the Internal Trust Boundaries which satisfies Security best practices (Threat/Security Models and Cloud/Network Architecture).
If there is an enterprise policy with strict rules that communication shall not be routed via DMZ/Public Internet and is a must to keep things within the Trusted Boundary of Internal Routes, I don't see any other choice but to go with the VPC peering : https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/peer-with-vpc-in-another-account.html
However, if requirements are less strict and you can use Public Internet to forward your Traffic out via DMZ, it is possible to achieve this with out sacrificing too much of Security (assuming that your EC2 with public IP on other account is providing service over SSL/TLS where your lambda can communicate with it over an Encrypted Communication Channel while validating the EC2's certificate).
This could be achieved by having Lambda associated with an Internal Subnet of your VPC to talk to the EC2 of other account with Public IP. https://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/VPC_Scenario2.html
Yes, You still can have your Lambda remaining inside the Internal Subnet. But you need a NAT GATEWAY and update the Routing Table for Lambda's Internal Subnet to point to the NAT GATEWAY (which should be assigned with an EIP) i.e. it will subsequently point to your INTERNET GATEWAY. By this you will make sure that your LAMBDA which, located in your private subnet of VPC can talk with outside i.e. with the EC2 instance, located in another account's with a Public IP. Therefore you can whitelist one IP in the SecurityGroups of your EC2 in Other Account which is the EIP of your NATGATEWAY which Lambda or any other Internal Components in that subnet will use to find their way out to the Internet.