Notes and Constraints on Using ECSs

Do not use ECSs as unauthorized servers for any illegal or violation service, such as gambling or cross-border VPN.
Do not use ECSs for fraudulent transactions, such as click farming on e-commerce websites.
Do not use ECSs to initiate network attacks, such as DDoS attacks, CC attacks, web attacks, brute force cracking, or to spread viruses and Trojan horses.
Do not use ECSs for traffic transit.
Do not use ECSs for web crawling.
Do not use ECSs to detect other systems like scanning or penetration unless otherwise being authorized.
Do not deploy any illegal websites or applications on ECSs.
Do not use ECSs to send spams.

Do not uninstall drivers on the ECS hardware.
Do not install external hardware devices, such as encryption dongles, USB flash drives, external hard disks, or bank USB security keys on ECSs.
Do not change the MAC address of NICs.
Do not install virtualization software on ECSs for nested virtualization.
Do not associate software licenses with the physical server hosting an ECS. Once an ECS is migrated from one physical server to another, the associated licenses may become invalid.
Do not deploy applications on a single ECS if you require high availability. Set up auto start for your ECSs or deploy applications in cluster or active/standby mode.
Data on ECSs running core applications needs to be backed up.
Monitoring needs to be configured for ECSs.
Do not change the default DNS server address. If you need to configure a public DNS address, configure both a public and a private DNS address on your ECS.
The system disk can boot from Basic Input Output System (BIOS) or Unified Extensible Firmware Interface (UEFI) according to the boot mode in the image file.
- You can change the OS to convert the boot mode of the ECS.
- You can create a UEFI or BIOS private image and use it to create an ECS.

Do not modify the /etc/issue file. Otherwise, the OS distribution will not be identified.
Do not delete system directories or files. Otherwise, the system may fail to run or start.
Do not change the permissions for or names of system directories. Otherwise, the system may fail to run or start.
Do not upgrade the kernel of the Linux unless necessary.
When you have to upgrade the Linux kernel, follow the instructions provided in How Can I Upgrade the Kernel of a Linux ECS?
Do not change the default /etc/resolv.conf of the DNS server. Otherwise, software sources and NTP may be unavailable.
Do not modify default intranet configurations, such as the IP address, subnet mask, or gateway address of an ECS. Otherwise, network exceptions may occur.
Manually specified IP addresses for Linux ECSs are generally static IP addresses. To avoid network exceptions caused by conflicts between NetworkManager and internal network services, do not enable NetworkManager when not required, such as when installing Kubernetes.