Prerequisites for EC2 Instance Connect

Install EC2 Instance Connect

To use EC2 Instance Connect to connect to an instance, the instance must have EC2 Instance Connect installed. You can either launch the instance using an AMI that comes pre-installed with EC2 Instance Connect, or you can install EC2 Instance Connect on instances that are launched with supported AMIs. For more information, see Install EC2 Instance Connect on your EC2 instances.

Ensure network connectivity

Instances can be configured to allow users to connect to your instance over the internet or through the instance's private IP address. Depending on how your users will connect to your instance using EC2 Instance Connect, you must configure the following network access:

• If your users will connect to your instance over the internet, then your instance must have a public IPv4 or public IPv6 address and be in a public subnet with a route to the internet. If you haven't modified your default public subnet, then it contains a route to the internet for IPv4 only, and not for IPv6. For more information, see Enable VPC internet access using internet gateways in the Amazon VPC User Guide.

• If your users will connect to your instance through the instance's private IPv4 address, then you must establish private network connectivity to your VPC, such as by using AWS Direct Connect, AWS Site-to-Site VPN, or VPC peering, so that your users can reach the instance's private IP address.

If your instance does not have a public IPv4 or public IPv6 address and you prefer not to configure the network access as described above, you can consider EC2 Instance Connect Endpoint as an alternative to EC2 Instance Connect. With EC2 Instance Connect Endpoint, you can connect to an instance using SSH or RDP even if the instance does not have a public IPv4 or public IPv6 address. For more information, see Connect to your Linux instance using the Amazon EC2 console.

Allow inbound SSH traffic

When using the Amazon EC2 console to connect to an instance

When users connect to an instance using the Amazon EC2 console, the traffic that must be allowed to reach the instance is traffic from the EC2 Instance Connect service. The service is identified by specific IP address ranges, which AWS manages through prefix lists. You must create a security group that allows inbound SSH traffic from the EC2 Instance Connect service. To configure this, for the inbound rule, in the field next to Source, select the EC2 Instance Connect prefix list.

AWS provides different managed prefix lists for IPv4 and IPv6 addresses for each Region. The names of the EC2 Instance Connect prefix lists are as follows, with region replaced by the Region code:

• IPv4 prefix list name: com.amazonaws.region.ec2-instance-connect

• IPv6 prefix list name: com.amazonaws.region.ipv6.ec2-instance-connect

For the instructions for creating the security group, see Task 2: Allow inbound traffic from the EC2 Instance Connect service to your instance. For more information, see Available AWS-managed prefix lists in the Amazon VPC User Guide.

When using the CLI or SSH to connect to an instance

Ensure that the security group associated with your instance allows inbound SSH traffic on port 22 from your IP address or from your network. The default security group for the VPC does not allow incoming SSH traffic by default. The security group created by the launch instance wizard allows incoming SSH traffic by default. For more information, see Rules to connect to instances from your computer.

Grant permissions

You must grant the required permissions to every IAM user who will use EC2 Instance Connect to connect to an instance. For more information, see Grant IAM permissions for EC2 Instance Connect.

Install an SSH client on your local computer

If your users will connect using SSH, they must ensure that their local computer has an SSH client.

A user's local computer most likely has an SSH client installed by default. They can check for an SSH client by typing ssh at the command line. If their local computer doesn't recognize the command, they can install an SSH client. For information about installing an SSH client on Linux or macOS X, see http://www.openssh.com. For information about installing an SSH client on Windows 10, see OpenSSH in Windows.

There is no need to install an SSH client on a local computer if your users use only the Amazon EC2 console to connect to an instance.

Meet username requirements

When using EC2 Instance Connect to connect to an instance, the username must meet the following requirements:

• First character: Must be a letter (A-Z, a-z), a digit (0-9), or an underscore (_)

• Subsequent characters: Can be letters (A-Z, a-z), digits (0-9), or the following characters: @ . _ -

• Minimum length: 1 character

• Maximum length: 31 characters