Why Can't My ECS Access the Internet Even After an EIP Is Bound?

Symptom

An ECS with an EIP bound cannot access the Internet.

Troubleshooting

Figure 1 shows the networking diagram for an ECS to access the Internet using an EIP.

Figure 1 EIP network diagram

Locate the fault based on the following procedure.

Figure 2 Troubleshooting procedure

1. Step 1: Check Whether the Is Running Properly
2. Step 2: Check Whether the Network Configuration of the Is Correct
3. Step 3: Check Whether an EIP Has Been Assigned and Bound to the
4. Step 4: Check Whether an EIP Is Bound to the Primary Network Interface of the
5. Step 5: Check Whether Required Security Group Rules Have Been Configured
6. Step 6: Check Whether Traffic from the Subnet Is Blocked

Step 1: Check Whether the Is Running Properly

Check the status.

If the status is not Running, start or restart the .

Step 2: Check Whether the Network Configuration of the Is Correct

1. Check whether the 's network interface has an IP address assigned.

   Log in to the , and run ifconfig or ip address to check the IP address of the ECS's network interface.

   If the runs Windows, run ipconfig.

2. Check whether the ECS's network interface has a virtual IP address.

   Log in to the , and run ifconfig or ip address to check whether the 's network interface has a virtual IP address. If the 's network interface has no virtual IP address, run the ip addr add <virtual-IP-address> eth0 command to configure an IP address for the 's network interface.

   Figure 3 Virtual IP address of a network interface
   

   Check whether the ECS's network interface has a default route. If there is no default route, run ip route add to add one.

   Figure 4 Default route
   

Step 3: Check Whether an EIP Has Been Assigned and Bound to the

Check whether an EIP has been assigned and bound to the . If no EIP has been assigned, assign an EIP and bind it to the .

Step 4: Check Whether an EIP Is Bound to the Primary Network Interface of the

Check whether an EIP is bound to the primary network interface of the . If there is no EIP bound to the primary network interface of the , bind one.

You can view the network interface details by clicking the Network Interfaces tab on the details page. By default, the first record in the list is the primary network interface.

Step 5: Check Whether Required Security Group Rules Have Been Configured

For details about how to add security group rules, see Adding a Security Group Rule.

If security group rules have not been configured, configure them based on your service requirements. (The remote IP address indicates the allowed IP address, and 0.0.0.0/0 indicates that all IP addresses are allowed.)

Step 6: Check Whether Traffic from the Subnet Is Blocked

Check whether the network ACL associated with the subnet of the ECS's network interface blocks traffic.

You can configure the network ACL on the VPC console. Make sure that the network ACL rules allow the traffic from the subnet.