Generally, any traffic to an EC2 instance will pass through the Security Group attached to the interface of the EC2 instance. However, when an SSH connection to an EC2 instance is established via AWS Session Manager, Security Groups have no impact. How is the traffic reaching the EC2 instance if not via the instance's interface (& Security Group)?
To use session manager you need the SSM agent running on your instances. This opens a bi-directional pipe out (this is critical, it does not listen on any ports) to the SSM service. This is then used to piggy pack signals over.
So when you make the ssh connection from your local machine to the instance via session manager, it is tunnelled over this connection.
A little extra information from AWS here: https://forums.aws.amazon.com/thread.jspa?threadID=270976
Related
When I go through the documents, using session manager we can connect instance in private subnet without having bastion host itself [direct port forwarding from local to private ec2].
But in RDS case, even though we are making connection using session manager we need a EC2 instance in between local and private RDS.
Could you anyone explain me why it is like that? please share some document that explains that as well.
AWS Systems Manager Session Manager allows you to connect to an instance in a Private Subnet because the instance is actually running an 'SSM Agent'. This piece of code creates an outbound connection to the AWS Systems Manager service.
Then, when you request a connection to the instance, your computer connects to the AWS Systems Manager service, which forwards the request to the agent on the instance. The AWS Systems Manager service is effectively acting as a Bastion for your connection.
AWS Systems Manager Session Manager cannot provide a connection to an Amazon RDS server because there is no ability to 'login' to an Amazon RDS server. Given that your RDS server is running in a Private Subnet, it is therefore necessary to port-forward via an EC2 instance in the same VPC as the RDS server. This can be done via a traditional Bastion EC2 instance in a Public Subnet, or via an EC2 instance in a Private Subnet by taking advantage of the Port Forwarding capabilities of AWS Systems Manager Session Manager.
I have got answered the same question in the AWS repost by #Uwe K. Please refer below.
SSM allows many more functions - and changes! - to an instance then just connecting to it. Having full SSM functionality on an RDS instance thus would undermine the Shared Responsibility Model we use for RDS (you could also say: it would violate the "Black Box" principle of RDS). Therefore, you need an intermediary instance that forwards the TCP Port exposed by RDS to your local machine.
Further reading:
The RDS-specific Shared Responsibility Model is explained here https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/UsingWithRDS.html
a general overview of the Shared responsibility model https://aws.amazon.com/compliance/shared-responsibility-model/
In order to connect to any EC2 instance with AWS systems manager, the SSM agent must be installed on that machine and the appropriate permissions need to be set up for the instance.
At the moment, AWS does not support this to RDS directly. In order for them to support such a setup, they'd probably need to install the agent on all RDS instances which generates quite some overhead and who knows what else the complexities of such a setup would have.
So at the present moment the most effective way to connect is setting up a tunnel via an EC2 instance.
I'm working with AWS, I have an EC2 instance (Amazon Linux) but I can't connect to it, I've checked all VPC parameters and they are enabled as well as the instance, but when I try to connect it using EC2 Instance Connect I get this message:
I'm using the default user account, also I generated a key pair however I'm getting this other message:
Also, session manager can't connect.
So my question is: what settings do I need to update or check in order to connect to my EC2 instance?
Thanks a lot for your comments.
There are multiple ways to login to an Amazon EC2 instance.
SSH
Your screenshot shows that you are wanting to login via SSH, but it is saying that no Keypair was selected when the instance was launched. Therefore, this option is not available for you.
EC2 Instance Connect
If you ware wanting to login to the Amazon EC2 instance using EC2 Instance Connect and you are experiencing connectivity problems, then make sure that your Security Group permits Inbound access on port 22 from the IP address range of the EC2 Instance Connect service (not your own IP address).
This is because the EC2 Instance Connect client on your computer connects to AWS on port 443 (as a web connection), and then the traffic goes from the EC2 Instance Connect service to the EC2 instance as a normal SSH connection on port 22. Therefore, the Security Group needs to permit Inbound connections on port 22 from the IP address range of the EC2 Instance Connect service (or you can be lazy and just select 0.0.0.0/0, but that is a lower level of security).
You can find the IP address ranges for AWS services at: AWS IP address ranges - AWS General Reference
Please note that your EC2 instance must be in a public subnet and you must connect via a public IP address.
AWS Systems Manager Session Manager
The Session Manager connects in a totally different way, without using SSH. It requires an Agent to be installed on the EC2 instance (and it is there by default if you launched from an Amazon Linux AMI). This Agent then creates an Outbound connection to AWS, so it does not require any Inbound security rules (but it does require the default "Allow All" Outbound rule).
Session Manager has the additional benefit that it allows you to connect to EC2 instances that are in private subnets, as long as the EC2 instance can access the Internet via a NAT Gateway or if the VPC has a VPC endpoint for Systems Manager.
I want to SSH AWS EC2 instance but by just only my computer, like SSH over the key. Only my computer can ssh into that instance. How can I configure it?
Thanks.
A common way to achieve that is to setup security group of your instance so that only your IP can access the instance:
Rules to connect to instances from your computer
As Marcin already answered, you should use security group to restrict access to your IP only. However, whenever you change the network, you have to manually edit that security group again.
One solution would be restrict access using mac address using firewall, something like this:
iptables -A INPUT -p tcp --destination-port 22 -m mac --mac-source xx:xx:xx:xx:xx:xx -j ACCEPT
iptables -A INPUT -p tcp --destination-port 22 -j DROP
A solution that doesn't require you to frequently update your security groups with your IP address is to use SSH through AWS Session Manager. Using SSH through Session Manager works exactly like a normal SSH connection. The SSH through Session Manager solution works by creating an SSH tunnel through your Session Manager connection. You can control access to your instance using IAM by restricting which AWS users can call StartSession on your EC2 instance. In your case, you can configure access to Session Manager only to the IAM User you configure on your computer.
You may even want to consider using Session Manager on it's own because that also allows you to connect to your instance and run commands... but using SSH through Session Manager gives you the security benefits of Session Manager and the familiarity of SSH. Session Manager allows you to connect to your EC2 instance without opening inbound ports on your security groups so it is more secure from a networking point of view especially if you have a publicly reachable instance. It uses normal HTTPS traffic so your instance will only need outbound access to the SSM Session Manager endpoints.
More details on how SSM Session Manager works here.
I have an EC2 instance on which I don't allow ssh.
I use EC2 Instance Connect to connect to it.
What is the alternative to scp Amazon exposes when using EC2 Instance Connect rather than ssh?
EC2 Instance Connect uses a web connection to Guacomole running on an AWS service, which then establishes an SSH connection on your behalf. There is no scp component available.
As an alternative, if you can establish a connection using AWS Systems Manager Session Manager, then it can also provide Port Forwarding that can be used for additional connections (such as scp).
I created an Elastic Beanstalk environment from Visual Studio and need to login to service the underlying ec2 vm.
I don't have an credentials for the server, so I wanted to use EC2 Instance Connect.
When I click connect, I get an error message:
We were unable to connect to your instance. Make sure that your instance’s network settings are configured correctly for EC2 Instance Connect. For more information, see Task 1: Configure network access to an instance.
Following the link, I found the instructions:
Ensure that the security group associated with your instance allows inbound SSH traffic on port 22 from your IP address or from your network.
(Amazon EC2 console browser-based client) We recommend that your instance allows inbound SSH traffic from the recommended IP block published for the service. Use the EC2_INSTANCE_CONNECT filter for the service parameter to get the IP address ranges in the EC2 Instance Connect subset.
How do I connect to the Elastic Beanstalk underlying EC2 via EC2 Instance Connect?
What I've tried:
I created a new security group that contains my client IP address, but that didn't work. Which makes sense, as it's the EC2 Instance Connect app running in the Console making the SSH connection, not my local machine.
Also looked at the the ip ranges json file (https://ip-ranges.amazonaws.com/ip-ranges.json), but not sure what to do with that.
I misunderstood the Set up EC2 Instance Connect instructions. This support article had clearer instructions: https://aws.amazon.com/premiumsupport/knowledge-center/ec2-instance-connect-troubleshooting/
Browser-based SSH connections require that your instance's security group inbound rules allow EC2 Instance Connect access to SSH on TCP port 22.
The key was to find the IP for EC2 Instance Connect and then create
a security group to whitelist that ip address.
EC2 Instance Connect IP can be retrieved via PowerShell by using Get-AWSPublicIpAddressRange (or curl). For us-west-2:
> Get-AWSPublicIpAddressRange -Region us-west-2 -ServiceKey EC2_INSTANCE_CONNECT | select IpPrefix
IpPrefix
--------
18.237.140.160/29
Once I configured my Security Group to use that Source I could connect.
Generally better way then using EC2 Instance Connect is through SSM System Manager. It does not require opening any inbound ports. Instead you should add/modify your install role to allow SSM to work. What's more you can control access to your instance using regular IAM permissions, unlike for EC2 Instance Connect.
Connection through SSM is in the same menu in the AWS console as EC2 Instance Connect. Thus, once you setup your instance role, wait few minutes for the instance to register with SSM, and once this happens you should be able to use SSM System Manager to connect to your instance from the console.
Regarding EC2 Instance Connect IP range. I don't know which range published applies only to EC2 Instance Connect. You would have to filter it by region probably and then find one which works. In worse case scenario its try-and-see approach.