Modifying the DNS Server Address and Adding Security Group Rules (Linux)

This topic describes how to add the DNS server address and security group rules to a Linux ECS or BMS to ensure successful download of the Agent installation package and successful monitoring data collection. This topic takes an ECS as an example. The operations for BMSs are similar.

You can modify the DNS configuration of an ECS in either of the following ways: command line and management console. Choose a method based on your habits.

DNS and security group configuration are intended for the primary NIC.

Modifying the DNS Server Address (Command Lines)

The following describes how to add the DNS server address to the resolv.conf file using command lines.

To use the management console, see Modifying the DNS Server Address (Management Console).

The nameserver value varies depending on the region. For details, see What Are Huawei Cloud Private DNS Server Addresses?

Log in to an ECS as user root.
Run the vi /etc/resolv.conf command to open the file.
Add the DNS server address, for example, nameserver 100.125.1.250 and nameserver 100.125.21.250 to the file. Press Esc and enter :wq. Then, press Enter to save the change.
Figure 1 Adding DNS server addresses (Linux)

Modifying the DNS Server Address (Management Console)

The following describes how to modify the DNS server address of an ECS in the region on the management console. The operations for BMSs are similar.

In the upper left corner, select a region and project.
Click Service List in the upper left corner. Under Compute, select Elastic Cloud Server.
On the ECS console, click the target ECS name to view its details.
In the ECS Information area of the Summary tab, click the VPC name.
The Virtual Private Cloud page is displayed.
Locate the target VPC and click the number of subnets.
In the subnet list, locate the subnet of the ECS and click its name.
On the subnet details page, click next to DNS Server Address in the Gateway and DNS Information area.
In the Edit DNS Server Address dialog box, enter a DNS server address.

Set the DNS server address to the value of nameserver in 3.
Click OK.

The new DNS server address is applied after the ECS or BMS is restarted.

Modifying the ECS Security Group Rules (Management Console)

The following describes how to modify security group rules for an ECS on the management console. The operations for BMSs are similar.

On the ECS details page, click the Security Groups tab.
The security group list is displayed.
Click a security group name.
On the security group details page, click Outbound Rules.
For BMSs:
1. Click the security group ID on the upper left.
2. Locate the security group and click Manage Rule in the Operation column.
On the Outbound Rules page, click Add Rule.

Add rules based on Table 1.

**Table 1** Security group rules
Priority	Action	Type	Protocol & Port		Destination IP Address	Description
1	Allow	IPv4	TCP	80	100.125.0.0/16	Used to download the Agent installation package from an OBS bucket to an ECS or BMS and obtain the ECS or BMS metadata and authentication information.
1	Allow	IPv4	TCP	53	100.125.0.0/16	Used by DNS to resolve domain names, for example, resolve the OBS domain name when you are downloading the Agent installation package, and resolve the Cloud Eye endpoint when the Agent is sending monitoring data to Cloud Eye.
1	Allow	IPv4	UDP	53	100.125.0.0/16	Used by DNS to resolve domain names, for example, resolve the OBS domain name when you are downloading the Agent installation package, and resolve the Cloud Eye endpoint when the Agent is sending monitoring data to Cloud Eye.
1	Allow	IPv4	TCP	443	100.125.0.0/16	Used to collect monitoring data to Cloud Eye.