This topic describes commonly used ports of ECS instances and the typical applications of these ports.

Commonly used ports

21FTPA port opened to the FTP service. The port is used to upload and download files.
22SSHSSH port, which is used to connect to a Linux instance by using a password in the command line mode.
23TelnetTelnet port, which is used to telnet to the ECS instance.
25SMTPA port opened to the SMTP service. The port is used to send emails.

For security purposes, ECS instances are disabled to access port 25. We recommend that you use port 465 to send emails. 

80HTTPThis port provides access to HTTP services, such as IIS, Apache, and Nginx.

For more information, see Verify if TCP port 80 works properly.

110POP3This port is used for the POP3 protocol to send and receive emails.
143IMAPThis port is used for the IMAP protocol to receive emails.
443HTTPSThis port is used to provide access to the HTTPS service. HTTPS is a protocol that provides encryption and transmission through secure ports.
1433SQL ServerThe TCP port of the SQL Server. This port is used for the SQL Server to provide external services.
1434SQL ServerThe UDP port of the SQL Server. This port is used to return which TCP/IP port the SQL Server uses.
1521OracleAn Oracle communication port. This port needs to be enabled when Oracle SQL is deployed on the ECS instance.
3306MySQLThe port through which the MySQL database provides external services.
3389Windows Server Remote Desktop ServicesThis port is used to connect to a Windows instance.
8080Proxy portSimilar to port 80, port 8080 is used by WWW agents to browse webpages. If you use port 8080 to access a website or use a proxy server, you must add :8080 after the IP address. If you install the Apache Tomcat service, the default service port is 8080.
137, 138, and 139NetBIOS protocol
  • Ports 137 and 138 are UDP ports used to transfer files through the network neighbor.
  • Port 139 provides access to the NetBIOS/SMB service.
The NetBIOS protocol is often used for Windows files, printer sharing, and Samba.

Typical applications of commonly used ports

ScenarioNetwork typeNICRule directionAuthorization policyProtocol typePort rangeAuthorization typeAuthorization objectPriority
Remote access to Linux instances through SSHVPCConfiguration is not required. InboundAllowSSH (22)22/22Address field access0.0.0.0/01
Classic networkInternet
Remote access to Windows instances through RDPVPCConfiguration is not required. InboundAllowRDP (3389)3389/3389Address field access0.0.0.0/01
Classic networkInternet
Ping ECS instances through the InternetVPCConfiguration is not required. InboundAllowICMP-1/-1Address field access or security group accessSet this parameter according to the authorization type.1
Classic networkInternet
Use an ECS instance as a Web server.VPCConfiguration is not required. InboundAllowHTTP (80)80/80Address field access0.0.0.0/01
Classic networkInternet
Upload or download files through FTP.VPCConfiguration is not required. InboundAllowCustom TCP20/21Address field access0.0.0.0/01
Classic networkInternet
  • Some operators consider ports 135, 139, 444, 445, 5800, and 5900 as high-risk ports and block these ports by default. Therefore, even if the ports are enabled for ECS instances, the ports cannot be accessed in some regions. We recommend that you use non-high-risk ports to meet your specific service needs.
  • For more information about Windows instance service ports, see Service overview and network port requirements for Windows.