security groups

AWS CloudFormation Security Group

December 29, 2021

AWS CloudFormation to create security groups. Includes self-refencing ingress and egress rules.

AWSTemplateFormatVersion: '2010-09-09'
Description: my-security-groups
######################################
Parameters:
  EC2Vpc:
    ConstraintDescription: Must be a valid VpcId
    Description: Select the VPC to use
    Type: AWS::EC2::VPC::Id
##############################################################################
Metadata:
  AWS::CloudFormation::Interface:
    ParameterGroups:
    - Label:
        default: VPC
      Parameters:
      - EC2Vpc
##############################################################################
Resources:
  EC2InstanceSecurityGroup1:
    Type: AWS::EC2::SecurityGroup
    Properties:
      VpcId: 
        Ref: EC2Vpc
      GroupDescription: my-security-group-1
      GroupName: my-security-group-1
      SecurityGroupIngress:
        - {CidrIp: 10.0.0.0/8,                        IpProtocol: tcp,  FromPort: '80',      ToPort: '80',    Description: 'HTTP'}  
      SecurityGroupEgress:
        - {CidrIp: 10.0.0.0/8,                        IpProtocol: udp,  FromPort: '123',     ToPort: '123',   Description: 'NTP'}  
        - {CidrIp: 10.0.0.0/8,                        IpProtocol: tcp,  FromPort: '53',      ToPort: '53',    Description: 'DNS'}
      Tags:
        - {Key: Name,         Value: 'my-security-group-1'}
  EC2InstanceSecurityGroup2:
    Type: AWS::EC2::SecurityGroup
    Properties:
      VpcId: 
        Ref: EC2Vpc
      GroupDescription: my-security-group-2
      GroupName: my-security-group-2
      SecurityGroupIngress:
        - {CidrIp: 0.0.0.0/0,                        IpProtocol: tcp,  FromPort: '443',     ToPort: '443',   Description: 'HTTP'}  
        - {CidrIp: 0.0.0.0/0,                        IpProtocol: icmp, FromPort: '-1',      ToPort: '-1',    Description: 'ICMP ping'}
      SecurityGroupEgress:
        - {CidrIp: 10.0.0.0/8,                       IpProtocol: udp,  FromPort: '123',     ToPort: '123',   Description: 'NTP'}  
        - {CidrIp: 10.0.0.0/8,                       IpProtocol: tcp,  FromPort: '53',      ToPort: '53',    Description: 'DNS'}
        - {CidrIp: 0.0.0.0/0,                        IpProtocol: icmp, FromPort: '-1',      ToPort: '-1',    Description: 'ICMP ping'}
      Tags:
        - {Key: Name,         Value: 'my-security-group-2'}
  MyIngressSelfAll:
    Type: AWS::EC2::SecurityGroupIngress
    Properties:
      GroupId: !Ref EC2InstanceSecurityGroup2
      SourceSecurityGroupId: !GetAtt EC2InstanceSecurityGroup2.GroupId
      IpProtocol: -1
      FromPort: 0
      ToPort: 65535
  MyEgressSelfAll:
    Type: AWS::EC2::SecurityGroupEgress
    Properties: 
      GroupId: !Ref EC2InstanceSecurityGroup2
      DestinationSecurityGroupId: !GetAtt EC2InstanceSecurityGroup2.GroupId
      IpProtocol: -1 
      FromPort: 0
      ToPort: 65535
##############################################################################
Outputs:
  SecurityGroupId:
    Description: The Security Group that was created
    Value: {Ref: EC2InstanceSecurityGroup1}
    Value: {Ref: EC2InstanceSecurityGroup2}
  StackName:
    Description: Name of this stack for Fn::ImportValue use by children of top level stack
    Value: {Ref: 'AWS::StackName'}

AWSTemplateFormatVersion: '2010-09-09' Description: my-security-groups ###################################### Parameters: EC2Vpc: ConstraintDescription: Must be a valid VpcId Description: Select the VPC to use Type: AWS::EC2::VPC::Id ############################################################################## Metadata: AWS::CloudFormation::Interface: ParameterGroups: - Label: default: VPC Parameters: - EC2Vpc ############################################################################## Resources: EC2InstanceSecurityGroup1: Type: AWS::EC2::SecurityGroup Properties: VpcId: Ref: EC2Vpc GroupDescription: my-security-group-1 GroupName: my-security-group-1 SecurityGroupIngress: - {CidrIp: 10.0.0.0/8, IpProtocol: tcp, FromPort: '80', ToPort: '80', Description: 'HTTP'} SecurityGroupEgress: - {CidrIp: 10.0.0.0/8, IpProtocol: udp, FromPort: '123', ToPort: '123', Description: 'NTP'} - {CidrIp: 10.0.0.0/8, IpProtocol: tcp, FromPort: '53', ToPort: '53', Description: 'DNS'} Tags: - {Key: Name, Value: 'my-security-group-1'} EC2InstanceSecurityGroup2: Type: AWS::EC2::SecurityGroup Properties: VpcId: Ref: EC2Vpc GroupDescription: my-security-group-2 GroupName: my-security-group-2 SecurityGroupIngress: - {CidrIp: 0.0.0.0/0, IpProtocol: tcp, FromPort: '443', ToPort: '443', Description: 'HTTP'} - {CidrIp: 0.0.0.0/0, IpProtocol: icmp, FromPort: '-1', ToPort: '-1', Description: 'ICMP ping'} SecurityGroupEgress: - {CidrIp: 10.0.0.0/8, IpProtocol: udp, FromPort: '123', ToPort: '123', Description: 'NTP'} - {CidrIp: 10.0.0.0/8, IpProtocol: tcp, FromPort: '53', ToPort: '53', Description: 'DNS'} - {CidrIp: 0.0.0.0/0, IpProtocol: icmp, FromPort: '-1', ToPort: '-1', Description: 'ICMP ping'} Tags: - {Key: Name, Value: 'my-security-group-2'} MyIngressSelfAll: Type: AWS::EC2::SecurityGroupIngress Properties: GroupId: !Ref EC2InstanceSecurityGroup2 SourceSecurityGroupId: !GetAtt EC2InstanceSecurityGroup2.GroupId IpProtocol: -1 FromPort: 0 ToPort: 65535 MyEgressSelfAll: Type: AWS::EC2::SecurityGroupEgress Properties: GroupId: !Ref EC2InstanceSecurityGroup2 DestinationSecurityGroupId: !GetAtt EC2InstanceSecurityGroup2.GroupId IpProtocol: -1 FromPort: 0 ToPort: 65535 ############################################################################## Outputs: SecurityGroupId: Description: The Security Group that was created Value: {Ref: EC2InstanceSecurityGroup1} Value: {Ref: EC2InstanceSecurityGroup2} StackName: Description: Name of this stack for Fn::ImportValue use by children of top level stack Value: {Ref: 'AWS::StackName'}

AWS Copy Security Group

December 28, 2021

You can copy rules from a security group to a new security group created within the same Region.

Open the Amazon Elastic Compute Cloud (Amazon EC2) console.

In the navigation pane, choose Security Groups.
Select the security group you’d like to copy.
For Actions, choose Copy to new.
The Create Security Group dialog opens, and is populated with the rules from your existing security group.
Specify a Security group name and Description for your new security group.
For VPC, choose the ID of the VPC.
Choose Create.

AWS Services that use Security Groups

November 9, 2021

Services that user Security Groups

EC2-Classic instance
Amazon EC2 instances
ElasticCache
AWS Elastic Beanstalk
Amazon Elastic MapReduce
Amazon RDS (Relational Database Service)
Amazon Redshift
Amazon ElastiCache
Amazon CloudSearch
Elastic Load Balancing
Lambda
Fargate
EFS

AWS EC2 List Firewall Rules

January 26, 2021

AWS EC2 Firewall rules are defined within security groups. Security groups are attached to an instance. An instance can have up to 5 security groups. Essentially, this script gathers all the security groups associated with an instance, loops through them, and then outputs the ingress and egress rules of each security group to a file in a text format.

#!/bin/bash
# set variables
instanceid='i-xxxxxxxxxxxxxxxx'
region='us-east-1'
profile='sample'
# log and temp files
output="ec2-sg.log"
tmpfil="ec2-sg.tmp"
# empty log at start
> $output
# get sg ids
aws ec2 describe-instances \
--instance-ids $instanceid \
--region $region \
--profile $profile \
--query 'Reservations[*].Instances[*].SecurityGroups[*].[GroupId]' --output text > $tmpfil
while read -r id; do
  echo '============================================' >> $output
  echo $id >> $output
  echo '============================================' >> $output
  echo '---------------- INGRESS -------------------' >> $output
  aws ec2 describe-security-groups \
  --group-ids $id \
  --profile $profile \
  --region $region \
  --output text \
  --query 'SecurityGroups[].IpPermissions[].[FromPort,ToPort,IpProtocol,IpRanges[].CidrIp[]|[0]]' >> $output
  echo '---------------- EGRESS --------------------' >> $output
  aws ec2 describe-security-groups \
  --group-ids $id \
  --profile $profile \
  --region $region \
  --output text \
  --query 'SecurityGroups[].IpPermissionsEgress[].[FromPort,ToPort,IpProtocol,IpRanges[].CidrIp[]|[0]]' >> $output
done < $tmpfil

Here’s a sample output.

============================================
sg-xxxxxxxxxxxxxxx
============================================
---------------- INGRESS -------------------
5985    5985    tcp     10.0.0.220/32
10005   10005   tcp     10.0.0.164/32
---------------- EGRESS --------------------
80      80      tcp     10.0.0.14/32
40000   65535   udp     10.0.0.0/8
3389    3389    tcp     10.0.0.96/32
9389    9389    tcp     10.0.0.0/8
5985    5986    tcp     10.0.0.96/32

AWS Security Groups IP Cidr

September 10, 2019

Here’s how to search for AWS Security Groups containing this IP Cidr.

aws ec2 describe-security-groups \
--filter Name=egress.ip-permission.cidr,Values='10.8.8.8/32' \
--query "SecurityGroups[*].{Name:GroupName}" \
--output text \
--profile default \
--region us-east-1

Search with ports.

aws ec2 describe-security-groups \
--filter Name=egress.ip-permission.cidr,Values='10.8.8.8/32' \
         Name=egress.ip-permission.from-port,Values='22' \
         Name=egress.ip-permission.to-port,Values='22' \
--query "SecurityGroups[*].{Name:GroupName}" \
--output text \
--profile default \
--region us-east-1

Query will only display the Security Group name.

Deleting AWS Security Groups

July 15, 2018

Every once in a while, you may need to do some cleanup and perform maintenance in AWS. One area where you can do some cleanup is the security groups. To check if security groups are in-used, is by way of the AWS Console. You can filter the security group via Instances. But that is not going to be enough. Security groups are also used in RDS as well as in load balancers. Overall, you have to be extra careful not to delete a security group that’s in-use. Fortunately, AWS will prompt you if you try to delete a security group that is still in-use. It’s a safety feature that can potentially save you from headaches.