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AWS Security Group With No Rules? (Explained)

AWS security group with no rules

AWS provides security groups with all sorts of functionality, and often serve as virtual firewalls for EC2 instances. They can be a great way to implicitly allow both. Outbound and inbound traffic to and from your respective resources. 

Not only that, but you can easily set rules to allow only certain types of traffic, such as https or http type of traffic coming into the instance. In other words, you can sift the type of traffic you would like on a port and protocol basis.

It can be common to ask, whether or not you can have a security group with no rules at all, and if you do have rules, how many can you have and what does that look like?

In short, when you create a security group designated for your instance, it comes already preloaded with outbound traffic but no inbound traffic. Therefore, only outbound traffic is allowed to wherever. This is useful when creating it, to protect from any malicious connections being made on an inbound basis.

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How many rules can an AWS security group have?

If you’re wondering how many rules an AWS Security group can have, you’ve come to the right place. Specifically, an AWS Security group can have a total of 120 rules, with an even split between inbound and outbound rules.

If you happen to need more rules for a particular instance security group, feel free to request a quota.

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How many rules are in a security group?

For any particular AWS Security Group, expect to have a default quota of about 120 Total rules. That means of those 120 rules, you can only have about 60 inbound rules and 60 outbound rules, respectively. 

If you’re needing more, you should ask yourself if you are properly architecting your application in such a way that allows for a decoupled way of operating. In other words, you will want to begin to think of architecting both your AWS Resources and Applications in such a way to make them decoupled from each other, rather than one Giant monolithic system.

What are security group rules in AWS?

AWS Security groups are essentially just virtual firewalls that are attached to the network interfaces of your EC2 Instances. This allows for stateful communications to and from your virtual machine.

That means, as you begin to play around with your security group, you’ll notice that if you allow traffic from a particular source on an inbound basis, then the respective outbound communications to further establish that connection are automatically allowed.

What’s also neat, is that you can even set rules to allow certain traffic from another security group. This helps relay the point of having de-coupled non-monolithic architectures that allow you to easily scale your workloads while implementing AWS security least privileges practices.

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Are AWS security group rules stateful?

AWS Security groups are considered stateful. That is because as you allow either inbound or outbound connections from your EC2 instance, the respective traffic to establish that connection is automatically allowed. Specifically, any inbound traffic you enable for a particular protocol is automatically allowed in the outbound form of that connection.

Final Thoughts

Creating and managing security groups is a cinch. All you have to do is go to the console on the AWS VPC side of things, and create one. Once created, you can attach it to any particular network card that is associated with an EC2 instance. 

In terms of rules, you can certainly begin to add and modify up to 120 inbound and outbound rules.