Security group in AWS is like a firewall(Virtual Firewall), it control inbound and outbound traffic from one or more instances. Security groups in AWS are Region Based.
Apart from maintaining Inbound and outbound Traffic using Security Group, if we want to add additional rule then we can use firewalld.
Security Group rules are associated with primary network Ethernet interface.
Security Group Rules
By Default Security Group all Outbound Traffic.Security Group rules are always permissive, you can't create deny rules.
You can add,modify and update rule in security group and it applied immediately.
When you associate multiple Security Group to a instance, the rule from each security group are effectively aggregated and applied to that instance. But This is not recommended way.
How to Create Security Group
- Choose security group from Navigation Panel
Fig 1 : Security Groups Under EC2 - Choose Create Security Group
- Enter name and description for new security group. for example - iamname_SG_region
- Select VPC from dropdown, if you don't create any vpc it show only default VPC
- Two Tab Inbound and Outbound
- Click on Add Rule to allow port for server.
Type : Protocol
Protocol :
Port Range :
Source(Inbound)/Destination(Outbound) :
Description : Add Description upto 255 character.
Create Security Group using Command Line
create-security-group
--description <value>
--group-name <value>
[--vpc-id <value>]
[--dry-run | --no-dry-run]
[--cli-input-json <value>]
[--generate-cli-skeleton <value>]
--description - Upto 255 Character
Constraints for EC2-VPC: a-z, A-Z, 0-9, spaces, and ._-:/()#,@[]+=;{}!$*
--group-name - upto 255 character, not start with sg
Constraints for EC2-VPC: a-z, A-Z, 0-9, spaces, and ._-:/()#,@[]+=;{}!$*
--vpc-id - id of VPC
For Example
aws ec2 create-security-group --group-name MySecurityGroup --description "My security group" --vpc-id vpc-1a2b3c4d
Note : You can add upto 50 rules per security group
You can create a security group and add rules that reflect the role of the instance that's associated with the security group. For example, an instance that's configured as a web server needs security group rules that allow inbound HTTP and HTTPS access, and a database instance needs rules that allow access for the type of database, such as access over port 3306 for MySQL.
You can create a security group and add rules that reflect the role of the instance that's associated with the security group. For example, an instance that's configured as a web server needs security group rules that allow inbound HTTP and HTTPS access, and a database instance needs rules that allow access for the type of database, such as access over port 3306 for MySQL.
The following are examples of the kinds of rules that you can add to security groups for specific kinds of access.
Topics
Web server
The following inbound rules allow HTTP and HTTPS access from any IP address. If your VPC is enabled for IPv6, you can add rules to control inbound HTTP and HTTPS traffic from IPv6 addresses.
| Protocol type | Protocol number | Port | Source IP | Notes |
|---|---|---|---|---|
| TCP | 6 | 80 (HTTP) | 0.0.0.0/0 | Allows inbound HTTP access from any IPv4 address |
| TCP | 6 | 443 (HTTPS) | 0.0.0.0/0 | Allows inbound HTTPS access from any IPv4 address |
| TCP | 6 | 80 (HTTP) | ::/0 | (VPC only) Allows inbound HTTP access from any IPv6 address |
| TCP | 6 | 443 (HTTPS) | ::/0 | (VPC only) Allows inbound HTTPS access from any IPv6 address |
Database server
The following inbound rules are examples of rules you might add for database access, depending on what type of database you're running on your instance. For more information about Amazon RDS instances, see the Amazon Relational Database Service User Guide.
For the source IP, specify one of the following:
- A specific IP address or range of IP addresses in your local network
- A security group ID for a group of instances that access the database
| Protocol type | Protocol number | Port | Notes |
|---|---|---|---|
| TCP | 6 | 1433 (MS SQL) | The default port to access a Microsoft SQL Server database, for example, on an Amazon RDS instance |
| TCP | 6 | 3306 (MYSQL/Aurora) | The default port to access a MySQL or Aurora database, for example, on an Amazon RDS instance |
| TCP | 6 | 5439 (Redshift) | The default port to access an Amazon Redshift cluster database. |
| TCP | 6 | 5432 (PostgreSQL) | The default port to access a PostgreSQL database, for example, on an Amazon RDS instance |
| TCP | 6 | 1521 (Oracle) | The default port to access an Oracle database, for example, on an Amazon RDS instance |
(VPC only) You can optionally restrict outbound traffic from your database servers, for example, if you want allow access to the Internet for software updates, but restrict all other kinds of traffic. You must first remove the default outbound rule that allows all outbound traffic.
| Protocol type | Protocol number | Port | Destination IP | Notes |
|---|---|---|---|---|
| TCP | 6 | 80 (HTTP) | 0.0.0.0/0 | Allows outbound HTTP access to any IPv4 address |
| TCP | 6 | 443 (HTTPS) | 0.0.0.0/0 | Allows outbound HTTPS access to any IPv4 address |
| TCP | 6 | 80 (HTTP) | ::/0 | (IPv6-enabled VPC only) Allows outbound HTTP access to any IPv6 address |
| TCP | 6 | 443 (HTTPS) | ::/0 | (IPv6-enabled VPC only) Allows outbound HTTPS access to any IPv6 address |
Access from another instance in the same group
To allow instances that are associated with the same security group to communicate with each other, you must explicitly add rules for this.
The following table describes the inbound rule for a VPC security group that enables associated instances to communicate with each other. The rule allows all types of traffic.
| Protocol type | Protocol number | Ports | Source IP |
|---|---|---|---|
| -1 (All) | -1 (All) | -1 (All) | The ID of the security group |
The following table describes inbound rules for an EC2-Classic security group that enable associated instances to communicate with each other. The rules allow all types of traffic.
| Protocol type | Protocol number | Ports | Source IP |
|---|---|---|---|
| ICMP | 1 | -1 (All) | The ID of the security group |
| TCP | 6 | 0 - 65535 (All) | The ID of the security group |
| UDP | 17 | 0 - 65535 (All) | The ID of the security group |
Access from local computer
To connect to your instance, your security group must have inbound rules that allow SSH access (for Linux instances) or RDP access (for Windows instances).
| Protocol type | Protocol number | Port | Source IP |
|---|---|---|---|
| TCP | 6 | 22 (SSH) | The public IPv4 address of your computer, or a range of IP addresses in your local network. If your VPC is enabled for IPv6 and your instance has an IPv6 address, you can enter an IPv6 address or range. |
| TCP | 6 | 3389 (RDP) | The public IPv4 address of your computer, or a range of IP addresses in your local network. If your VPC is enabled for IPv6 and your instance has an IPv6 address, you can enter an IPv6 address or range. |
Path MTU Discovery
The path MTU is the maximum packet size that's supported on the path between the originating host and the receiving host. If a host sends a packet that's larger than the MTU of the receiving host or that's larger than the MTU of a device along the path, the receiving host returns the following ICMP message:
Destination Unreachable: Fragmentation Needed and Don't Fragment was Set
To ensure that your instance can receive this message and the packet does not get dropped, you must add an ICMP rule to your inbound security group rules.
| Protocol type | Protocol number | ICMP type | ICMP code | Source IP |
|---|---|---|---|---|
| ICMP | 1 | 3 (Destination Unreachable) | 4 (Fragmentation Needed and Don't Fragment was Set) | The IP addresses of the hosts that communicate with your instance |
Ping your instance
The
ping command is a type of ICMP traffic. To ping your instance, you must add the following inbound ICMP rule.| Protocol type | Protocol number | ICMP type | ICMP code | Source IP |
|---|---|---|---|---|
| ICMP | 1 | 8 (Echo) | N/A | The public IPv4 address of your computer, or a range of IPv4 addresses in your local network |
To use the
ping6 command to ping the IPv6 address for your instance, you must add the following inbound ICMPv6 rule.| Protocol type | Protocol number | ICMP type | ICMP code | Source IP |
|---|---|---|---|---|
| ICMPv6 | 58 | 128 (Echo) | 0 | The IPv6 address of your computer, or a range of IPv6 addresses in your local network |
DNS server
If you've set up your EC2 instance as a DNS server, you must ensure that TCP and UDP traffic can reach your DNS server over port 53.
For the source IP, specify one of the following:
- A specific IP address or range of IP addresses in a network
- A security group ID for a group of instances in your network that require access to the DNS server
| Protocol type | Protocol number | Port |
|---|---|---|
| TCP | 6 | 53 |
| UDP | 17 | 53 |
Amazon EFS file system
If you're using an Amazon EFS file system with your Amazon EC2 instances, the security group that you associate with your Amazon EFS mount targets must allow traffic over the NFS protocol.
| Protocol type | Protocol number | Ports | Source IP | Notes |
|---|---|---|---|---|
| TCP | 6 | 2049 (NFS) | The ID of the security group. | Allows inbound NFS access from resources (including the mount target) associated with this security group. |
To mount an Amazon EFS file system on your Amazon EC2 instance, you must connect to your instance. Therefore, the security group associated with your instance must have rules that allow inbound SSH from your local computer or local network.
| Protocol type | Protocol number | Ports | Source IP | Notes |
|---|---|---|---|---|
| TCP | 6 | 22 (SSH) | The IP address range of your local computer, or the range of IP addresses for your network. | Allows inbound SSH access from your local computer. |
Elastic Load Balancing
If you're using a load balancer, the security group associated with your load balancer must have rules that allow communication with your instances or targets.
| Inbound | ||||
| Protocol type | Protocol number | Port | Source IP | Notes |
| TCP | 6 | The listener port |
For an Internet-facing load-balancer: 0.0.0.0/0 (all IPv4 addresses)
For an internal load-balancer: the IPv4 CIDR block of the VPC
| Allow inbound traffic on the load balancer listener port. |
| Outbound | ||||
| Protocol type | Protocol number | Port | Destination IP | Notes |
| TCP | 6 | The instance listener port | The ID of the instance security group | Allow outbound traffic to instances on the instance listener port. |
| TCP | 6 | The health check port | The ID of the instance security group | Allow outbound traffic to instances on the health check port. |
The security group rules for your instances must allow the load balancer to communicate with your instances on both the listener port and the health check port.
| Inbound | ||||
| Protocol type | Protocol number | Port | Source IP | Notes |
| TCP | 6 | The instance listener port |
The ID of the load balancer security group
| Allow traffic from the load balancer on the instance listener port. |
| TCP | 6 | The health check port | The ID of the load balancer security group | Allow traffic from the load balancer on the health check port. |
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