How to Fix the Security Group Attached to the EC2 Instance

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I can connect to AWS EC2 Instance using PuTTY at my home by laptop. But when I bring the laptop to some cafe that provides free Wifi, it ends up with timeout error.

In order to solve this problem, I need to fix the security group attached to the EC2 instance to allow the connection from the cafe’s public IP.

Unfortunately, I can not figure out what is an appropriate word to search for.
Please advise me where I should read and follow to fix this problem?
If it's possible, I want to see anything other than Amazon AWS official page, because it's difficult to read.

Best Answer

You need to:

Log in
Search for "VPC" in the search bar at the top
Click on VPC
Click on "security groups" on the left
Find your security group
Edit your security group

You can also get to this by navigating to the instance under the EC2 service, then clicking on the details panel and there'll be a link to the security group.

When you edit the security group, you can add 'my current ip address'. If you do this from the cafe it should work.

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Ssh – Cannot SSH into Amazon EC2 instance

I think your logs are snipped.

Here are the things you need to check

Check if the name you are connecting to is correct. It may have changed and we have no idea about you setup/

Check the security group of the EC2 instance , is SSH allowed by firewall? What about IP

Check in your log files if it copied the SSH Public Key

AWS CloudFormation: VPC default security group

Referencing the default security group is possible using:

{ "Fn::GetAtt" : ["VPC", "DefaultSecurityGroup"] }

Where "VPC" is your VPC resource name.

With AWS::EC2::SecurityGroupIngress and AWS::EC2::SecurityGroupEgress, you can augment the permissions of this default security group.

I think this is what you want:

"VPCDefaultSecurityGroupIngress": {
  "Type" : "AWS::EC2::SecurityGroupIngress",
  "Properties" : {
    "GroupId": { "Fn::GetAtt" : ["VPC", "DefaultSecurityGroup"] },
    "IpProtocol":"tcp",
    "FromPort":"22",
    "ToPort":"22",
    "CidrIp":"0.0.0.0/0"
  }
},

As mentioned by @artbristol and @gabriel, this allows Ingress/Egress rules to be added to the default security group for the VPC in a single stack deployment.

I'm pretty sure that the self-referential problem still impacts any attempts at changing any of the other properties on the default security group of the VPC. A good example of this would be adding Tags, or a Description. If you wish to change these things, you'll have to deal with extraneous security groups laying around.

Best Answer

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Ssh – Cannot SSH into Amazon EC2 instance

AWS CloudFormation: VPC default security group

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