My goal:
I have two instance EC2, one is an API that is public and another is a microservice, which needs only to communicate with API.
what I have tried so far:
I have one security group where both instances were attached. In this group, I created every possible rules. (I can ping each of them through private IP, but i can't make a request from my API to my microservice).
I made a simple diagram showing my goal and my problem
More details:
Both instance are running on the same VPC and subnet.
Trying telnet or curl, the response is connection refused
My inbound rules security group:
My outbound rules security group:
Security Group rules operate on each resource individually. Putting instances in the 'same' security group does not guarantee that they can communicate with each other.
The correct security setup would be:
One Security Group on the 'public' instance (Public-SG) that allows Inbound connections on port 80/443 from the Internet (0.0.0.0/0) and default rules that permit All Outbound traffic.
One Security Group on the 'private' microservice instance (Microservice-SG) that allows Inbound connections on port 8086 from Public-SG and default rules that permit All Outbound traffic.
That is, Microservice-SG should specifically reference Public-SG in its Inbound rules.
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.
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 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).
I am very new to AWS and networking. I have been playing with network ACL. I realized that if I don't allow outbound port 443 (HTTPS) on the network ACL, I wouldn't be able to use a browser to go to https://www.google.com from within the EC2 instance in the subnet associated with this ACL.
Likewise, if I don't allow outbound port 80, I wouldn't be able to go to http://www.cnn.com.
This confused me. When I allow port 80 outbound on the ACL, am I allowing the EC2 to talk to port 80 on the CNN server, from an ephemeral port on my EC2, or am I allowing the EC2 to initiate a connection from port 80 on the EC2?
use the security groups at instance level to have security at instance level.And unlike security group, ACL is stateless and works at subnet level i.e if you want your instances to communicate over port 80(http) then you have add an inbound and outbound rule allowing port 80.
You don't have to add any rules. The default network ACL is configured to allow all traffic to flow in and out of the subnets to which it is associated. Each network ACL also includes a rule whose rule number is an asterisk. This rule ensures that if a packet doesn't match any of the other numbered rules, it's denied. You can't modify or remove this rule.
Rules allow all IPv6 traffic to flow in and out of your subnet. We also add rules whose rule numbers are an asterisk (Catch All) that ensures that a packet is denied if it doesn't match any of the other defined numbered rules.
A network ACL has separate inbound and outbound rules (Stateless), and each rule can either allow or deny traffic.
Out Bound Rules allow outbound traffic from the subnet to the Internet. In other words it is matching the traffic flow with the defined rules in the ACLs list and apply it (ALLOW/DENY).
If you have private instances that should not be accessible by public users in the internet it is best practice from security point of view to place these instances in a private subnet and use NAT instance in a public subnet and make all traffic flow goes through this NAT instance to make patch updates and get the public access.
For more information, Check Amazon Docs