The following table lists commonly used ECS instance ports.

Port Service Description
21 FTP A port opened by the FTP service is used for uploading and downloading files.
22 SSH An SSH port is used to connect to a Linux instance by using a password in command-line mode.
23 Telnet The Telnet port is used for Telnet to log on to the ECS instance.
25 SMTP The port that is open to the SMTP service is used for sending mails.

Based on security concerns, ECS instance Port 25 is restricted by default. Open a ticket to open it. See apply to open TCP port 25.

80 HTTP Provides access to HTTP services, such as IIS, Apache, and Nginx.

You can verify if TCP port 80 works properly for port troubleshooting.

110 POP3 Used for the POP3 protocol, which is the protocol for sending and receiving emails.
143 IMAP Used for IMAP (Internet Message Access Protocol), which is the protocol for receiving emails.
443 HTTPS Used to provide access to the HTTPS service. HTTPS is a protocol that provides encryption and transmission through secure ports.
1433 SQL Server The TCP port of the SQL Server is used for external service by SQL Server.
1434 SQL Server SQL Server UDP port is used to return which TCP/IP port SQL Server uses.
1521 Oracle Oracle communications port. The port which needs to be released by Oracle SQL is deployed on the ECS instance.
3306 MySQL The port through which the MySQL database provides external service.
3389 Windows Server Remote Desktop Services Windows Server Remote Desktop Services port can be used to connect to a Windows instance.
8080 Proxy port As with 80 port, port 8080 is commonly used in WWW agent service to achieve web browsing. If you are using port 8080, when you visit a Web site or use a proxy server, you must add :8080 after the IP Address: 8080. After you install the Apache Tomcat service, the default service port is 8080.
137, 138, 139 NetBIOS protocol
  • 137 and 138 are UDP ports that are used to transfer files through the network neighbor.
  • The connection entering through the port 139 attempts to obtain the NetBIOS/smb service.
NetBIOS protocols are often used for Windows files, printer sharing, and samba.

Some ports cannot be accessed

Problem: The ECS instance listens for the corresponding port, but the port is not accessible in some areas, while other ports can be accessed normally.

Analysis: Some operators judge ports 135, 139, 444, 445, 5800, 5900, and so on as high-risk ports, so they are blocked by default.

Solution: We recommend that you change the port to other non-high-risk ports for business operation.

Related topic

For more information on how to release a service port through a security group, see add security group rules.