Common ECS Ports

When adding a security group rule, you must specify a port or port range for communications. Traffic is then allowed or denied if traffic matches this rule. Suppose a client requests to remotely log in to an ECS using SSH. When the request reaches the security group, the IP address and port (22) of the client will be checked. If the IP address and the port match the allow rules in the security group, the request is allowed.

Table 1 lists some high-risk ports that are blocked by default. Even if you have added a security group rule to allow access over these ports, traffic over these ports in restricted regions is still denied. In this case, do not use these high-risk ports for your services.

**Table 1** High-risk ports
Protocol	Port
TCP	42, 135, 137, 138, 139, 444, 445, 593, 1025, 1068, 1433, 1434, 3127, 3128, 3129, 3130, 4444, 4789, 5554, 5800, 5900, 8998, 9995, and 9996
UDP	135 to 139, 1026, 1027, 1028, 1068, 1433, 1434, 4789, 5554, 9995, and 9996

Common Ports

Table 2 lists the common ports used by ECSs. You can configure security group rules to allow traffic over specific ports used by ECSs. For details, see Adding a Security Group Rule. For more information about requirements for Windows, see Service overview and network port requirements for Windows.

**Table 2** Common ports used by ECSs
Port	Protocol	Description
21	FTP	Used by FTP services for uploading and downloading files. For configuration examples, see Remotely Connecting to an ECS from a Local Server to Upload or Download Files over FTP.
22	SSH	Used to remotely connect to a Linux ECS. For configuration examples, see Remotely Logging In to an ECS from a Local Server. For details about how to log in to a Linux ECS, see Linux ECS Login Overview.
23	Telnet	Used to remotely log in to an ECS using Telnet.
25	SMTP	Used to send emails. For security purposes, TCP port 25 is disabled in the outbound direction by default. For details about how to open the port, see Why Is Outbound Access Through TCP Port 25 Restricted?
80	HTTP	Used to access websites over HTTP. For configuration examples, see Deploying a Website on an ECS.
110	POP3	Used to receive emails using Post Office Protocol version 3 (POP3).
143	IMAP	Used to receive emails using Internet Message Access Protocol (IMAP).
443	HTTPS	Used to access websites over HTTPS. For configuration examples, see Deploying a Website on an ECS.
1433	SQL Server	A TCP port of the SQL Server for providing services. For configuration examples, see Allowing External Instances to Access the Database Deployed on an ECS.
1434	SQL Server	A UDP port of the SQL Server for returning the TCP/IP port number used by the SQL Server. For configuration examples, see Allowing External Instances to Access the Database Deployed on an ECS.
1521	Oracle	Used for Oracle database communications. This port must be enabled on the ECSs where Oracle SQL Server is deployed. For configuration examples, see Allowing External Instances to Access the Database Deployed on an ECS.
3306	MySQL	Used by MySQL databases to provide services. For configuration examples, see Allowing External Instances to Access the Database Deployed on an ECS.
3389	Windows Server Remote Desktop Services	Used to connect to Windows ECSs. For configuration examples, see Remotely Logging In to an ECS from a Local Server. For details about how to log in to a Windows ECS, see Login Overview (Windows).
8080	Proxy	Used by the WWW proxy service for web browsing, like port 80. If you use port 8080, you need to add :8080 after the IP address when you visit a website or use a proxy server. If Apache Tomcat is installed, its default service port is 8080.
137, 138, and 139	NetBIOS	Used for Windows files, printer sharing, and Samba. Ports 137 and 138: UDP ports that are used when files are transferred using Network Neighborhood (My Network Places). Port 139: Connections from this port try to access the NetBIOS/SMB service.

Example Use Cases of Ports

The following table provides examples of security group rules configured with common ports. For more scenarios, see Security Group Examples.

**Table 3** Example use cases of ports
Use Case	Direction	Priority	Action	Type	Protocol & Port	Source
Remotely logging in to a Linux ECS using SSH	Inbound	1	Allow	IPv4	TCP (Custom ports): 22	IP address: Authorized IP address
Remotely logging in to a Windows ECS using RDP	Inbound	1	Allow	IPv4	TCP (Custom ports): 3389	IP address: Authorized IP address
Remotely uploading and downloading files using FTP	Inbound	1	Allow	IPv4	TCP (Custom ports): 20-21	IP address: Authorized IP address
Deploying a website on an ECS	Inbound	1	Allow	IPv4	TCP (Custom ports): 80	IP address: 0.0.0.0/0
Using Ping to test network connectivity of an ECS	Inbound	1	Allow	IPv4	ICMP: All	IP address: 0.0.0.0/0

Parent Topic: Security Group

Previous topic: Security Group Examples

Next topic: Managing a Security Group

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