Control network traffic with security groups - Amazon EMR

Control network traffic with security groups

Security groups act as virtual firewalls for EC2 instances in your cluster to control inbound and outbound traffic. Each security group has a set of rules that control inbound traffic, and a separate set of rules to control outbound traffic. For more information, see Amazon EC2 security groups for Linux instances in the Amazon EC2 User Guide.

You use two classes of security groups with Amazon EMR: Amazon EMR-managed security groups and additional security groups.

Every cluster has managed security groups associated with it. You can use the default managed security groups that Amazon EMR creates, or specify custom managed security groups. Either way, Amazon EMR automatically adds rules to managed security groups that a cluster needs to communicate between cluster instances and AWS services.

Additional security groups are optional. You can specify them in addition to managed security groups to tailor access to cluster instances. Additional security groups contain only rules that you define. Amazon EMR does not modify them.

The rules that Amazon EMR creates in managed security groups allow the cluster to communicate among internal components. To allow users and applications to access a cluster from outside the cluster, you can edit rules in managed security groups, you can create additional security groups with additional rules, or do both.


Editing rules in managed security groups may have unintended consequences. You may inadvertently block the traffic required for clusters to function properly and cause errors because nodes are unreachable. Carefully plan and test security group configurations before implementation.

You can specify security groups only when you create a cluster. They can't be added to a cluster or cluster instances while a cluster is running, but you can edit, add, and remove rules from existing security groups. The rules take effect as soon as you save them.

Security groups are restrictive by default. Unless a rule is added that allows traffic, the traffic is rejected. If there is more than one rule that applies to the same traffic and the same source, the most permissive rule applies. For example, if you have a rule that allows SSH from IP address, and another rule that allows access to all TCP traffic from the range, the rule that allows all TCP traffic from the range that includes takes precedence. In this case, the client at might have more access than you intended.


Use caution when you edit security group rules to open ports. Be sure to add rules that only allow traffic from trusted and authenticated clients for the protocols and ports that are required to run your workloads.

You can configure Amazon EMR block public access in each Region that you use to prevent cluster creation if a rule allows public access on any port that you don't add to a list of exceptions. For AWS accounts created after July 2019, Amazon EMR block public access is on by default. For AWS accounts that created a cluster before July 2019, Amazon EMR block public access is off by default. For more information, see Using Amazon EMR block public access.


Amazon EMR aims to use inclusive alternatives for potentially offensive or non-inclusive industry terms such as "master" and "slave". We've transitioned to new terminology to foster a more inclusive experience and to facilitate your understanding of the service components.

We now describe "nodes" as instances, and we describe Amazon EMR instance types as primary, core, and task instances. During the transition, you might still find legacy references to the outdated terms, such as those that pertain to security groups for Amazon EMR.