i have a jupyter notebook on one ec2 instance that want to get the data from data service that is deployed on other ec2 instance. should i put ingress and egress rules for each other on both instances? I'm quite new on the field, so any explanations are appreciated! :)
Yes, you can create 2 different security groups and attach to each one.
You can allow inbound traffic from a particular security group, all instances that have the security group attached can send traffic to the instance on the port you specify.
Another important thing no notice is that security groups are stateful, when you set outbound rules the response traffic is allowed regardless of the inbound rules.
Security Group Outbound rules allow all traffic by default. Typically, you should not modify these settings.
The best way to configure you setup is:
Create a Jupyter-SG security group and associate it with your Jupyter EC2 instance. Add whatever rules you use to connect with the instance (eg SSH).
Create a Data-SG security group and associate it with your "Data Service" EC2 instance. Add a rule permitting inbound access on the desired port, with Source set to the Security Group ID of Jupyter-SG.
This tells the Data-SG security group to permit inbound access from the Jupyter instance (or, more accurately, from any instance that is associated with the Jupyter-SG security group).
Related
I have a license server that has a static IP set up inside the same security group and VPC as the EC2s I’m spinning up using terraform. Basically I want the license server and these EC2s to be able to communicate. At the moment they can’t because the security doesn’t add the EC2s as an inbound rule so that the license server also gets it as an inbound rule (same security group). I’m wondering how to add the IP of the EC2 I’m spinning up in terraform to the inbound of its security group so that it can talk to the license server?
There is no such concept as being "inside the same security group". Security Groups rules apply to each instance individually.
The correct configuration is:
Create a Security Group for the EC2 instances (EC2-SG) that permits appropriate Inbound access to use the instance, and
Create a Security Group for the licensing server (License-SG) that permits Inbound access on the licensing port from EC2-SG
That is, you need TWO security groups. License-SG will permit inbound access from any EC2 instance that has is associated with EC2-SG. You can have more security group as necessary for your instances -- simply add them as sources in License-SG.
Security Groups can also refer to themselves. In your current situation, where the instances and the licensing server are all associated with the same security group, you could add a rule that permits inbound connections from itself. However, this is also saying that the instances are permitting inbound connections from the licensing server, which would not be a correct configuration.
Please note that all communication within the VPC should take place via private IP addresses, otherwise the traffic exits the VPC and then comes in again, which does not allow Security Groups to operate correctly (and also costs you more money!).
I am trying to understand this statement:
"You can reference AWS Security Groups from other Security Groups."
What exactly does this mean?
This is how I understood this. I created a security group and call it "SG-10" and attached it to an instance "EC2-10". The SG "SG-10" has allow port 443 defined inside it.
Now, I create a security group and call it "SG-20" and attached this to an instance "EC2-20". This also has port 443 allowed. Now, if I call "SG-10" inside "SG-20" does this mean that "EC2-10" will be able to connect to "EC2-20" on port 443.?
Regards,
Nik.
if I call "SG-10" inside "SG-20"
No, you can not call a security group, this does not make any sense.
If a security group A references security group B, it does mean that the instance to which the security group A is attached allows inbound or outbound traffic to another instance to which security group B is attached. But if you want to send traffic form instance with security group A to the instance with security group B, you have to use the IP or the DNS of the instance B.
Usually the reason why we would want to reference a security group instead of an IP, is that the IP might change over time or it is not exposed at all. A fairly common example is having an application load balancer (ALB) and a group of EC2 instances which allow traffic only from the ALB. The IP address of the ALB changes over time, so in order to be able to receive traffic from the ALB, we can reference the security group attached to it.
In we want to reference a security group from another security group, we have to edit the rules of the initial security group:
As an example of referencing security groups, imagine a 3-tier architecture:
A Load Balancer receiving traffic from the Internet and sending requests to an Amazon EC2 instance
An Amazon EC2 instance receiving requests from the Load Balancer and sending queries to an Amazon RDS database
An Amazon RDS database receiving requests from the EC2 instance
This would involve 3 security groups:
A security group on the Load Balancer (LB-SG) that allows incoming traffic on port 80/443.
A security group on the EC2 instance (App-SG) that allows incoming traffic on port 80 only from the load balancer. It does this by setting the source to LB-SG.
A security group on the RDS database (DB-SG) that allows incoming traffic on the relevant port (eg 3306) only from the EC2 instance. It does this by setting the source to App-SG.
All security groups allow All Outbound Traffic.
By referencing other security groups, resources can be added/removed without having to change the security groups. For example, another EC2 instance could be launched and assigned the App-SG security group. This new instance would then be able to communicate with the database since DB-SG allows incoming traffic from App-SG, without being tied to any specific IP addresses.
If a resource is associated with multiple security groups, then all rules apply to the resource. Security Groups only say what is 'Allowed'. They do not include 'Deny' rules.
In your SG-10/SG-20 example, you do not mention the source of the traffic, so it is not possible to answer your question. If you want EC2-20 to accept connections from EC2-10, then the SG-20 security group should allow connections with the Source set to SG-10.
As an aside, I should mention that Network ACLs should normally be left at their default "Allow All" settings unless there is a specific networking requirement (eg creating a DMZ).
I've been burned on this before by trying to connect to an EC2 instance's public address... sounds very similar to your setup. Please check this question: Source Security group isnt working as expected in aws. Actually. When you wire up the inbound rule so that the source is a security group, you must communicate through the source instance's private address.
I have a ec2 instance that is running a website and associates ALB.
normally as a practice inside the ec2 instance security group, alb security group is referenced, but here the client has a configuration in such a way that inside ec2 instance the source is name of the security group itself.
security group for ec2 instance whose name is
sg-0bc7e4b8b0fc62ec7 - default
As per my understanding of aws security group, under an inbound rule when it comes to source, we can mention IP address, or CIDR block or reference another security group.
But what does this mean for an inbound rule where ALL traffic, all ports are allowed but for source = sg-0bc7e4b8b0fc62ec7 / default.
I am confused with usage of the same name of the security group as source, what this rule will mean?
Each VPC has a default security group (SG). In this SG, inbound rule allows all incoming traffic from "itself". This means that
When you specify a security group as the source for a rule, traffic is allowed from the network interfaces that are associated with the source security group for the specified protocol and port.
In other words, if you have two instances that use the default VPC SG, they can only communicate with each other. No other inbound traffic is allow to either instance.
The use of SG as source is a good practice and if often used between load balancer (LB) and its instances, or between instances and RDS database. In the first case the instances allow incoming traffic only from the SG of the LB, while in the second case, db instance allows incoming connections only from SG of the instance.
So i am trying to build a private vpc having a private and a public subnet. I want to communicate 2 linux ec2 machines with each other within same vpc. Also please explain inbound and outbound rules with ACLs in simplest way.
If both Amazon EC2 instances serve the same function (are operationally the 'same'), then:
Create a Security Group
Add in Inbound Rule on the security group permitting access from the Security Group (itself) on the desired port number
Attach the Security Group to both instances
This will allow both instances to communicate with each other because security groups are applied to each instance individually, so the Inbound Rules must permit access from 'itself'.
If the EC2 instances serve different purposes, (eg one is an app server, one is a database server):
Create a Security Group on the App server (App-SG) with desired inbound permissions from the Internet
Create a Security Group on the Database server (DB-SG) with inbound permissions on the desired port from App-SG
That is, DB-SG specifically refers to App-SG when defining inbound permissions.
Do not modify ACLs in the VPC unless you have a very specific reason for limiting network access (eg creating a DMZ).
I'm investigating security setting of an EC2 instance, and taking a look at
security group setting.
In one of the inbound rule's source, instead of source IP address, it has it's own security group's ID and Group name.
What does this mean?
In AWS, Security Groups are applied to each resource individually.
So, let's say you had:
A security group (App-SG) permitting inbound HTTP access on port 80
Two Amazon EC2 instances in a public subnet associated with App-SG
Even though both EC2 instances have the same security group, they are not able to SSH with each other. Some people sometimes say that the instances would be "in" the same security group (which gives the impression that they can communicate with each other), but it is more appropriate to say that the instances are associated with the same security group.
The thing to remember is that security group rules are applied to each instance individually.
So, if you wanted to permit both instances to SSH to each other, you could add an inbound rule to the security group:
Protocol: SSH (Port 22)
Source: App-SG
This says: "Allow any resource associated with this security group to receive traffic from any other resource associated with this security group on port 22".
You might say that security group can "communicate with itself", but the reality is that the same rules are applied separately on each resource.