Security Group Configuration Examples

Remotely Logging In to an ECS from a Local Server

A security group denies all external requests by default. To remotely log in to an ECS from a local server, add an inbound security group rule based on the OS running on the ECS.

• To remotely log in to a Linux ECS using SSH, enable the SSH (22) port. For details, see Table 2.
• To remotely log in to a Windows ECS using RDP, enable the RDP (3389) port. For details, see Table 3.

  Table 2 Remotely logging in to a Linux ECS using SSH

  Direction	Protocol & Port	Source
  Inbound	TCP: 22	IP address: 0.0.0.0/0

  Table 3 Remotely logging in to a Windows ECS using RDP

  Direction	Protocol & Port	Source
  Inbound	TCP: 3389	IP address: 0.0.0.0/0

  

  If the source is set to 0.0.0.0/0, remotely logging in to the ECS through any IP address is allowed. To ensure security, set the source to a specific IP address based on service requirements. For details about the configuration example, see Table 4.

  Table 4 Remotely logging in to an ECS using a specified IP address

  ECS Type	Direction	Protocol & Port	Source
  Linux ECS	Inbound	TCP: 22	IP address: 192.168.0.0/24
  Windows ECS	Inbound	TCP: 3389	IP address: 10.10.0.0/24

Remotely Connecting to an ECS from a Local Server to Upload or Download Files

By default, a security group denies all external requests. If you need to remotely connect to an ECS from a local server to upload or download files, you need to enable FTP ports 20 and 21.

You must first install the FTP server program on the ECSs and check whether ports 20 and 21 are working properly.

Setting Up a Website on an ECS to Provide Services Externally

A security group denies all external requests by default. If you have set up a website on an ECS that can be accessed externally, you need to add an inbound rule to the ECS security group to allow access over specific ports, such as HTTP (80) and HTTPS (443).

Using ping Command to Verify Network Connectivity

By default, a security group denies all external requests. If you need to run the ping command on an ECS to verify network connectivity, add an inbound rule to the ECS security group to allow access over the ICMP port.

Enabling ECSs In Different Security Groups to Communicate Through an Internal Network

ECSs in the same VPC but associated with different security groups cannot communicate with each other. If you want to share data between ECSs in a VPC, for example, ECSs in security group sg-A need to access MySQL databases in security group sg-B, you need to add an inbound rule to security group sg-B to allow access from ECSs in security group sg-A over MySQL port 3306.

ECS Providing Database Access Service

A security group denies all external requests by default. If you have deployed the database service on an ECS and need to allow other ECSs to access the database service through an internal network, you need to add an inbound rule to the security group of the ECS with the database service deployed to allow access over ports, for example, MySQL (3306), Oracle (1521), MS SQL (1433), PostgreSQL (5432) and Redis (6379).

In this example, the source is for reference only. Set the source address based on actual requirements.

Allowing ECSs to Access Only Specific External Websites

By default, a security group allows all outbound traffic. Table 11 lists the default rules. If you want to allow ECSs to access only specific websites, configure the security groups of the ECSs as follows:

1. First, add outbound rules to allow traffic over specific ports and to specific IP addresses.

   Table 10 Enabling instances in different security groups to communicate through an internal network

   Direction	Protocol & Port	Source
   Outbound	TCP: 80	IP address: 132.15.XX.XX
   Outbound	TCP: 443	IP address: 145.117.XX.XX

2. Then, delete the original outbound rules that allow all traffic shown in Table 11.

   Table 11 Default outbound rules in a security group

   Direction	Protocol & Port	Destination	Description
   Outbound	All	0.0.0.0/0	This rule allows access from instances in the security group to any IPv4 address over any port.