I have a VPC with a public subnet containing a NAT gateway and a private subnet containing ec2 instances running my application.
A public ALB provides inbound internet access to the application running in the private subnets.
I also want to allow access to this ALB over a site-to-site VPN using a customer gateway and transit gateway.
What is the best pattern to do this that avoids duplicating the ALB and it’s configuration (i.e avoid having a public and internal ALB)? Is it possible to run a single private ALB that the VPN users will connect to directly and route public internet traffic to it from a public NLB?
You should be able to use transit gateway routing tables to accomplish this. Create two TGW attachment points; one for your VPN and one for the subnet where your ALB resides. Now, disassociate those two attachment points from the main TGW routing table. Create two new TGW routing tables:
one that points 0.0.0.0/0 to your ALB subnet attachment and associate that to your VPN TGW attachment (enable DNS resolution)
one that points 0.0.0.0/0 to your VPN subnet attachment and associate that to your ALB subnet TGW attachment (enable DNS resolution)
In this way any traffic coming in from your VPN will land in your private ALB subnet and resolve to the ALB private IP address. Any traffic leaving your ALB destine to a non-local IP address (the return traffic) will be routed to your VPN TGW attachment.
Although I have not tested your specific scenario, I was able to use this method to route TGW traffic to and from GWLB endpoints.
You can leave your routes for public internet traffic to your ALB as they are (from your public NLB). Now you have two ways customers can reach the same ALB; one public and one private.
You can use AWS API Gateway private integration Pattern using VPC link to provide public access to your service, and host your service behind internal application load balancer like the following:
Also you may need to consider dns resolution between your AWS and on premises networks.
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.
Can I download and install patches from Internet using Route53, without having NAT Gateway and IGW?
I think you might be a little confused regarding what Route53 is:
Amazon Route 53 is a highly available and scalable cloud Domain Name System (DNS) web service.
Source
So, it has nothing to do with downloading patches. You can use it to handle your domains, and it can work nicely with several AWS services.
Now, regarding your question. If you want an EC2 instance to access the Internet and download its security patches, you will need an Internet Gateway configured on the VPC of the instance. On the other hand, the NAT Gateway is only necessary if your instance is configured on a private subnet. A private subnet doesn't have direct access to the Internet Gateway, so you need to provide a NAT Gateway to allow your instances to reach it. EC2 instances in public subnets can be assigned public IPs. An instance with a Public IP can access the Internet directly through the Internet Gateway without needing a NAT Gateway.
Another resource you are going to have to configure is Route Tables. Each subnet is assigned to a single Route Table. Once attached, it will use the routes define on the Route Table to handle their instances traffic. A Route Table that handles private subnets will have a default route pointing to a NAT Gateway. And a public Route Table will have a default route pointing directly to the Internet Gateway. Bear in mind that the NAT Gateway should always be instantiated on public subnets.
Take a look at the following documentation site for more information:
VPC Internet Gateway
VPC Subnet
VPC Route Tables
Route53 is a DNS service and its function is DNS resolution. You need NAT Gateway for outbound internet access from private subnet
I have currently three tomcat servers running off of Apache which listens to certain IP address each on one machine to redirect to certain routes. I want to move them up to AWS VPC for higher redundancy. Can i have three NICs on an instance that act the same as my prem version? How do i get the NAT up and running like my router does for the websites?
example:
eth0 = root.test.com 192.168.0.20/32 to 81.100.10.2,
eth1 = stage.test.com 192.168.0.21/32 to 81.100.10.3,
eth2 = test.root.com 92.168.0.22/32 to 81.100.10.4
You can create and attach more than one EIN per instance. See limits here:
https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-eni.html#AvailableIpPerENI
You can then route to these ENIs however you like, just reference them in your route tables. Recall each VPC has a default route table, but you can have additional route tables at the subnet level. Create two subnets one public, one private, place your NAT Gateway on your public subnet, and route all internet traffic from the private subnet through your NAT Gateway.
For a subnet to be public, we need to attach an Internet Gateway (IGW) to the VPC and update the route table of the public subnet to send non-local traffic to the IGW.
Our aim is to get our Elastic Beanstalk setups to route traffic through a NAT gateway as we require for certain traffic connecting to API's which require IP whitelisting. Rather than make modifications to the current setup, I have created a separate/isolated VPC & EC2 instance to familiarise and test the setup. However I am yet to get the setup working as desired.
Here is the setup
VPC (vpc-77049811) with CIDR of 10.0.0.0/16
Internet gateway (igw-4d4b212a) assigned to mentioned VPC
Subnet (subnet-096d8a53) with CIDR of 10.0.1.0/24
NAT Gateway (nat-00bb49204627de7e6) attached to mentioned subnet and assigned Elastic IP
Route table attached to mentioned VPC and associate with mentioned subnet
1x EC2 Instance assigned to VPC and its own Elastic IP and Disabled Source/Destination Check
Route Table Setup
10.0.0.0/16 local
0.0.0.0/0 igw-4d4b212a
With the above setup, and am able to log into the server and make a curl request to get the servers public IP address (curl icanhazip.com). As soon as I add a rule to the route table for the url's resolved IP's to route through the NAT gateway though, I am unable to ping or request the curl request as it will timeout.
Rules added to route table which do not work
45.63.64.111/32 nat-00bb49204627de7e6
144.202.71.30/32 nat-00bb49204627de7e6
Not sure if I've overlooked something here or maybe I have misunderstood the concept and use cases for the NAT gateway?
This is public IP 45.63.64.111. You need IGW to reach to this traffic.
You either do that by directly redirecting your traffic to IGW
OR
You do that by directing to NAT then further directing that traffic to IGW
Directing to IGW part is missing.
Nat gateway is used for EC2 in private subnets (which does not have IGW attached to it). In scenario above, EC2 is in public subnet so ideally it does not need NAT.
Here is what I would do to use NAT-
1. Place EC2 in private subent. and have a Route table where all outgoing traffic to nat-gateway.
2. Nat-gateway which is in public subnet will forward your traffic to IGW.
It seems like you have misunderstood the purpose of a NAT.
Its purpose is to provide outbound internet access to instances in a private subnet without allowing any inbound connectivity - i.e. a subnet where the routing table does NOT have an entry for:
0.0.0.0/0 igw-4d4b212a
If you want to restrict access from your EC2 instance to specific IP addresses, put your NAT in the public subnet, create a private subnet, and put your instance in the private subnet. Then add the two routes to the route table associated with the private subnet:
45.63.64.111/32 nat-00bb49204627de7e6
144.202.71.30/32 nat-00bb49204627de7e6
If you simply want to restrict access of your EC2 instance to a couple of IP addresses, you can only create routes for those addresses:
45.63.64.111/32 igw-4d4b212a
144.202.71.30/32 igw-4d4b212a
Be aware that with this last option, your instance can be reached from the internet if you have rules open in your security groups.
I'm putting the instances behind the aws loadbalancer, I have configured the routable and attached the IGW to it, created the loadbalancer and added this instance to the aws loadbalancer every things work well, the endpoint URL of the AWS loadbalancer able to load the HTTP pages
Now i have removed the IGW from the route table and tested it again, the AWS loadbalalncer endpoint URL not able to load the page, but the instace status shows in AWS loadbalancer as inService
Why the IGW is required when loadbalancer is configured over private subnet, it technically Mean it's a public subnet, which is blocking me to create a NAT inatance
A subnet without a default route pointing to the igw-xxxxxxxx Internet Gateway object is, by definition, a private subnet. If you remove the igw from a public subnet, you now have a private subnet.
Placing an Internet-facing load balancer (ELB) in such a private subnet is incorrect.
It sounds as though you are making a commonly-made -- but incorrect -- assumption that the ELB should be configured in the same subnets as the instances behind it. This is also incorrect.
Provision the ELB in public subnets, without regard to the subnets the instances behind it were placed in.
In summary:
Internet-facing ELB requires a public subnet for placement.
NAT instance requires a public subnet for placement.
The instances that use these services (NAT and ELB) belong in different -- private -- subnets, different subnets than the ELB and NAT instances.
ELB and NAT can be placed together in the same subnets, or separately, as long as the subnets are public (have the IGW as their default route) and are in the same availability zones.
I believe you cannot do anything without the IGW attached to the routing table where the subnet is attached to.
Another way to do this is to spin off a NAT instance(can be found in AWS marketplace) in the public subnet, add it to your private route table where your original instance is on (0.0.0.0/0 - instanceid) all the traffic will be routed through the NAT instance.
Here mainly we have to see two things, provided subnet for the elasticloadbalancer is public or private.
Every VPC should have one IGW to connect to the public, every trafic should go through the IGW only. If VPC connected to the IGW, IGW distribute internet to the all instance which are in that VPC, if route table changed to the particular rt, internet traffic can send to only that instance. Here in ELB instance is in service because both are in the same VPC and can communicate each other means checks the status. This IGW will work main role when we are using the NAT.
Always we provide ip range for the IGW or rt as 0.0.0.0/0, it represents as public.
The following link will explain more : http://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/VPC_Scenario2.html
This small explanation might be helpful for someone.
Let me cover your two questions
the AWS loadbalalncer endpoint URL not able to load the page, but the instace status shows in AWS loadbalancer as inService
This is the default behaviour of load balancer , since internally load balancer and your instance may be in the same VPC so they are able to communicate that is why loadbalancer is showing inService status.
Second question Why the IGW is required when loadbalancer is configured over private subnet, it technically Mean it's a public subnet, which is blocking me to create a NAT inatance
You need IGW if you want to access any resources especially EC2 , Loadbalancer from internet. however if you put your load balancer in private subnet it means IGW is not associated with the subnet having loadbalancer in it and hence this load balancer is not accessible outside your VPC that is reason that you were not able to load your page.
NAT instance is usually used when you want your private subnet instances should be able to initiate request over internet and has nothing to do with normal load balancing setup unless and untill you want dont want to install any updates from internet to your instance.
You are trying to access webpage publicly and removing the route entry IGW from the loadbalncer subnet.
The Subnet without IGW will become Private, Hence you can't access it.
First, a subnet with route table that route traffic via the internet gateway (IGW) is a public subnet. An IGW is required because the subnets created in AWS VPC are internal IPs and as internal IPs are not routable via the internet, traffic to and fro EC2 instances that belongs to an internal IP needs a way to complete these request. This is where an IGW comes into play. The IGW allows your EC2 instance to make outbound request to the internet and allows other user/client to make inbound request to your ec2 instance.
A public subnet are group of IPs (called subnets) in your VPC that allows internet traffic to and fro your ec2 instance. A subnet without an Internet gateway is a private subnet. As you already guess no traffic is allowed in or out.
That said, instances in VPC which are in Private subnet still need to initiate an outbound request to the internet to download software or perform update. In this case you have to create and attach a NAT gateway or NAT instance to the private subnet. NAT Gateway and NAT instance only allow outbound traffic to the internet but not the the other way round. In some cases you might want your production EC2 to be in the private subnet and ELB in public subnet for security reason.
ELB usually belong to the public subnet so it reachable from the internet as is your case as well.
TO answer some of your question - when you deleted the IGW from the route table, your ELB automatically becomes a private subnet as such your web page stops loading.
Also, you could still see the ec2 instance behind the ELB as InService even when you deleted the IGW because the ELB and EC2 instance can communicate via the internal IP as they are in same network or VPC.
The ELB needs a route to the internet in order to send you the response over internet.. As simple as that.
Configure your ELB in public subnet, regardless of where your instances are present.
Basically there are two types of load balancers.
1)Internal
2) External
Internal load balancers are those which are launched in a private subnet which will be accessible only internally by the instances on same vpc of the internal elb
External load balancers are which are accessible over the internet which should be launched in a subnet which has internet gateway attached to it and which has route table configured properly to route the requests.
If you attach an internet gateway to a subnet it becomes a public subnet.Also if you create a load-balancer which you need to be accessible from internet it should be a External load balancer and aws will not allow it launch in a private subnet.The instances are showing in service because its communicating internally using private ip-address.