Amazon Elastic Compute Cloud
User Guide for Linux Instances

Authorizing Inbound Traffic for Your Linux Instances

Security groups enable you to control traffic to your instance, including the kind of traffic that can reach your instance. For example, you can allow computers from only your home network to access your instance using SSH. If your instance is a web server, you can allow all IP addresses to access your instance via HTTP, so that external users can browse the content on your web server.

To enable network access to your instance, you must allow inbound traffic to your instance. To open a port for inbound traffic, add a rule to a security group that you associated with your instance when you launched it.

To connect to your instance, you must set up a rule to authorize SSH traffic from your computer's public IP address. To allow SSH traffic from additional IP address ranges, add another rule for each range you need to authorize.

If you need to enable network access to a Windows instance, see Authorizing Inbound Traffic for Your Windows Instances in the Amazon EC2 User Guide for Windows Instances.

Before You Start

Decide who requires access to your instance; for example, a single host or a specific network that you trust. In this case, we use your local system's public IP address. You can get the public IP address of your local computer using a service. For example, we provide the following service: To locate another service that provides your IP address, use the search phrase "what is my IP address". If you are connecting through an ISP or from behind your firewall without a static IP address, you need to find out the range of IP addresses used by client computers.


If you use, you enable all IP addresses to access your instance using SSH. This is acceptable for a short time in a test environment, but it's unsafe for production environments. In production, you'll authorize only a specific IP address or range of addresses to access your instance.

For more information about security groups, see Amazon EC2 Security Groups for Linux Instances.

Adding a Rule for Inbound SSH Traffic to a Linux Instance

Security groups act as a firewall for associated instances, controlling both inbound and outbound traffic at the instance level. You must add rules to a security group that enable you to connect to your Linux instance from your IP address using SSH.

To add a rule to a security group for inbound SSH traffic using the console

  1. In the navigation pane of the Amazon EC2 console, choose Instances. Select your instance and look at the Description tab; Security groups lists the security groups that are associated with the instance. Choose view rules to display a list of the rules that are in effect for the instance.

  2. In the navigation pane, choose Security Groups. Select one of the security groups associated with your instance.

  3. In the details pane, on the Inbound tab, choose Edit. In the dialog, choose Add Rule, and then choose SSH from the Type list.

  4. In the Source field, specify the public IP address of your computer, in CIDR notation. For example, if your IP address is, specify to list this single IP address in CIDR notation. If your company allocates addresses from a range, specify the entire range, such as

    For information about finding your IP address, see Before You Start.

  5. Choose Save.

To add a rule to a security group using the command line

You can use one of the following commands. Be sure to run this command on your local system, not on the instance itself. For more information about these command line interfaces, see Accessing Amazon EC2.

Assigning a Security Group to an Instance

You can assign a security group to an instance when you launch the instance. When you add or remove rules, those changes are automatically applied to all instances to which you've assigned the security group.

After you launch an instance in EC2-Classic, you can't change its security groups. After you launch an instance in a VPC, you can change its security groups. For more information, see Changing an Instance's Security Groups in the Amazon VPC User Guide.