I am trying to run the command “aws lambda list-functions” from an ec2 inside my private subnet that I connected to using a bastion host. The lambda has been deployed to the same VPC and private subnet, but when I try to run the command it times out. They are in the same region, and I have been able to connect to some of my other services within this ec2 but can’t connect to my lambda service endpoint.
I tried connecting from an ec2 inside a public subnet and that worked fine, but can't connect from ec2 inside the private subnet.
You have two options for that:
Setup NAT gateway in a public subnet along with route tables entries directly internet traffic in a private subnet to the NAT.
Setup VPC interface endpoint for lambda so that you can connect to the lambda service without needing internet connectivity.
Related
I'm trying to create an AWS Cloud9 environment to access a DocumentDB server for direct access. However, when creating the Cloud9 environment it takes forever then dies with an error regarding an inability to connect to the functional backing EC2 instance. My VPC has 2 public and private subnets and no matter which subnet I use all of them fail with the same error. I have a web server running on the same VPC under one of the private subnets that can be accessed from the open internet perfectly fine and access my DocumentDB database. I have two NAT gateways, one hooked to each of my public subnets. I also have route tables set up to access the open internet. Is there something that could be obviously affecting the Cloud9 environment's ability to connect to it's EC2 instance?
It turns out that my private subnet route tables were misconfigured; they were forwarding 0.0.0.0/0 to an internet gateway, not to my NAT gateway.
Is there anyone who can explain me that situation below ?
I connected to Ec2 intance in private subnet via Bastion Host.Then I created a vpc gateway endpoint to reach s3. I assigned the required role to ec2 and the connection to s3 is done. My question is, how can Ec2 instance in private subnet download something from the internet?
A VPC endpoint is used to access a certain service, in this case S3, over the AWS network instead of over the internet.
If you want your instance to be able to talk to the internet, you'll need to configure a NAT gateway in a public subnet, and you'll need to configure the route table of the private subnet to forward traffic to the NAT gateway.
A simple solution would be:
Put everything in a Public Subnet
Assign a Public IP address to the Amazon EC2 instance
Use Security Groups to secure access on the Amazon EC2 instance (that is, only allow Inbound connections from the Bastion)
The effective result is the same as using a Private Subnet, but the EC2 instance will be able to establish Outbound connections to the Internet (but not Inbound, so it remains secure).
Anyone here that have a ec2 instance that is on a private subnet in AWS that is able to connect to outside FTP server? It seems that my ec2 instance cannot connect to 3rd party ftp servers without moving to public subnet and using elastic/public ip.
Private subnet by default have no connectivity to outside world or internet. But there is a resource called NAT Gateway that you can configure in your VPC to provide an outgoing internet connectivity from your private subnets.
You can use a network address translation (NAT) gateway to enable
instances in a private subnet to connect to the internet or other AWS
services, but prevent the internet from initiating a connection with
those instances.
You can follow the link here to setup the NAT gateway.
https://aws.amazon.com/premiumsupport/knowledge-center/nat-gateway-vpc-private-subnet/
Private subnets do not have internet connectivity by default. You need to create a nat gateway on the public subnet. Nat gateways are bit expensive. You can also create a nat instance in that case.
I am now trying to configure a route table for a private subnet, and I config an AWS Lambda function with these subnets. When I use an ENI, I will receive a ssl error (violation of protocol) when I was trying to make an API call through Internet (like a call to the ServiceNow API). When I use NAT, it works.
I investigate for a while, but still confused about when should we use ENI (or nat)? What is the difference?
When an AWS Lambda function is not connected to a VPC, it has direct access to the Internet.
When an AWS Lambda function is connected to a VPC, and requires access to the Internet, then the configuration should be:
Associate the Lambda function with a private subnet in the VPC
Create a NAT Gateway in a public subnet
Configure the Route Table for the private subnet to route 0.0.0.0/0 traffic to the NAT Gateway
You probably received the error because the Lambda function was unable to reach the endpoint on the Internet. I don't know why you specifically received an "SSL Error".
An Elastic Network Interface (ENI) is the virtual network connection between a resource (eg an AWS Lambda function) and a VPC. Think of it like a 'network card' that connects it to the network.
A NAT Gateway is a service that does IP address translation. It accepts the local traffic and sends it to the Internet, also passing back responses. It enables Internet access from private subnets while preventing inbound access to the private subnet.
I have been working on integrating an Amazon Lambda function with connection to a RDS for the mySQL DB and an external API. To access the API, there needed to be an internet gateway and then security groups that allowed connection from 0.0.0.0/0.
I have a a public subnet and private subnet. The public subnet routes to the internet gateway but the private subnet routes to a NAT.
This lead me to think that if I ran the Lambda function with the Public subnet, it would connect to the internet. However, every time it timed out. But, when I ran the lambda function from within the private subnet, it worked! So it the NAT seems to work since that is what the private sunet was associated with, but just using the internet gateway does not work.
Does anyone have any explanation for this?
For an Amazon Lambda function to connect to the Internet, ONE of the following is required:
The Lambda function is not connected to a VPC, OR
The Lambda function is connected to a private subnet and there is a NAT Gateway/NAT Instance configured, OR
The Lambda function is connected to a public subnet and an Elastic IP address is assigned to the Elastic Network Interface (ENI) being used by the Lambda function in the subnet
Merely connecting a Lambda function to a public subnet (without an EIP) will not provide Internet access.