Why Can't I Log In to My Windows ECS?

Symptom

A Windows ECS cannot be logged in to due to some reasons. For example, the network is abnormal, the firewall does not allow access to the local port for accessing the remote desktop, or the ECS vCPUs are overloaded.

This section describes how to troubleshoot login failures on a Windows ECS.

If you cannot log in to your Windows ECS, follow the instructions provided in Checking the VNC Login. Then, locate the login fault by referring to Fault Locating.

Checking the VNC Login

Check whether you can log in to the ECS using VNC on the management console.

1. Log in to the management console.
2. Under Computing, choose Elastic Cloud Server.
3. In the Operation column of the target ECS, click Remote Login.

If the VNC login still fails, record the resource details and fault occurred time for further fault locating and analysis.

Fault Locating

If you can log in to the ECS using VNC but cannot log in to the ECS using a remote desktop connection, locate the fault as follows.

The following fault causes are sequenced based on their occurrence probability.

If the fault persists after you have ruled out a cause, check other causes.

Checking the ECS Status

Check whether the ECS is in the Running state on the management console. If the ECS is stopped, start it and try to log in to the ECS again.

Figure 1 Checking the ECS status

Checking the Login Mode

Check the login mode you set when you created the ECS.

Figure 2 Login Mode

• Password: Check whether the login password is correct. If you forgot your password, reset the password. After you reset the password, restart the ECS for the new password to take effect.
• Key pair: If your ECS is authenticated using a key pair, parse the private key file to obtain a password.

Checking Whether the ECS Is Overloaded

If the bandwidth or CPU usage of the ECS is excessively high, login failures may occur.

If you have created an alarm rule in Cloud Eye, the system automatically sends an alarm notification to you when the bandwidth or CPU usage reaches the threshold specified in the rule.

To resolve this issue, perform the operations described in Why Is My Windows ECS Running Slowly?

• If the login failure is caused by high CPU usage, perform the following operations to reduce the CPU usage:
  • Stop certain processes that are not used temporarily and try again.
  • Verify that the Windows Update process is not running on the backend.
  • Restart the ECS.
  • Reinstall the ECS OS. Back up important data before the reinstallation.
  • If the ECS OS cannot be reinstalled due to important data, replace the disk attached to the ECS. To do so, back up data on the original disk, detach the disk from the ECS, attach the new disk to the ECS, and copy data to the new disk.

  You can also upgrade the vCPUs and memory by modifying the ECS specifications.

• If the login fails because the bandwidth exceeds the limit, perform the following operations:

  For instructions about how to increase the bandwidth, see Changing an EIP Bandwidth.

After you perform the preceding operations, try to remotely log in to the ECS again.

Checking Whether an ECS Has an EIP Bound

An ECS can access the Internet only after it has an EIP bound.

Before logging in to an ECS using MSTSC, make sure that an EIP has been bound to the ECS. For details, see Assigning an EIP and Binding It to an ECS.

If you log in to an ECS over an intranet, for example, using VPN or Direct Connect, you do not need to bind an EIP to the ECS.

Checking Whether the Network Is Normal

Use a local PC in another network or use another hotspot to access the ECS. Check whether the fault occurs on the local network. If so, contact the carrier to resolve this issue.

After you perform the preceding operations, try to remotely log in to the ECS again.

Checking Whether the Firewall Is Correctly Configured

Check whether the firewall is enabled.

1. Log in to the Windows ECS.
2. Click the Windows icon in the lower left corner of the desktop and choose Control Panel > System and Security > Windows Firewall.
   Figure 3 Windows Firewall
   
3. Choose Check firewall status > Turn Windows Firewall on or off.

   View and set the firewall status.

   Figure 4 Turn off Windows Firewall
   

Ensure that the remote access port on the local end is allowed on the firewall. The default port is TCP 3389.

If the port configured in the inbound rule of the firewall is different from that configured on the remote server, the remote login will fail. If this occurs, add the port configured on the remote server in the inbound rule of the firewall.

The default port is 3389. If you use another port, add that port in the inbound rule of the firewall.

After you perform the preceding operations, try to remotely log in to the ECS again.

Checking Whether the Remote Access Port Is Correctly Configured

1. Check whether port 3389 (used by default) on the ECS is accessible.

   Ensure that port 3389 has been added in the inbound rule.

   On the ECS details page, click the Security Groups tab and check port 3389 in the inbound rule of the security group.

   Figure 5 Checking remote access ports
   

   If you need to modify security group rules, see Modifying a Security Group Rule.

2. Check whether the remote connection port is changed.
   1. Choose Start > Run, enter cmd, and press Enter. In the CLI, enter regedit to open Registry Editor.
   2. In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\TerminalServer\WinStations\RDP Tcp\PortNumber, check whether the port is the default port 3389. If not, change the port to port 3389.

      

3. Check whether the number of connections is limited.

   Check the internal remote desktop configuration of the ECS.

   1. Choose Start > Run, enter cmd, and press Enter. In the CLI, enter gpedit.msc to open Local Group Policy Editor.
   2. Choose Computer Configuration > Administrative Templates > Windows Components > Remote Desktop Services > Remote Desktop Session Host > Connections. Then, in the Limit number of connections dialog box, check whether the number of connections is limited.

      

      

      If Limit number of connections is set to Enabled, a remote connection to the Windows ECS may fail when the number of connections exceeds the limit. In such a case, disable Limit number of connections or set a larger limit for connections.

Checking the IP Address Whitelist for SSH Logins (with HSS Enabled)

After HSS is enabled, you can configure an IP address whitelist for SSH logins as required. The IP address whitelist controls SSH access to ECSs, effectively preventing account cracking.

After you configure the allowlist, SSH logins will be allowed only from IP addresses in the allowlist.

1. On the Events page, check whether a local host IP address is intercepted due to brute force cracking.
2. Check whether the IP address whitelist for SSH logins has been enabled. If it has been enabled, ensure that the IP address of the local host has been added to the IP address whitelist.
   

   • Before enabling this function, ensure that all IP addresses that need to initiate SSH logins are added to the allowlist. Otherwise, you cannot remotely log in to your ECS through SSH.
   • Exercise caution when adding a local IP address to the allowlist. This will make HSS no longer restrict access from this IP address to your ECSs.

Checking the Remote Desktop Protocol on the ECS

Make sure that the remote desktop protocol has been enabled on the ECS (only required for MSTSC logins).

Log in to the ECS using VNC and enable the remote desktop protocol.

For details, see Enabling RDP.

Checking Whether the Access Is Blocked by Antivirus Software

Third-party antivirus software may lead to a failure in accessing the ECS.

If third-party antivirus software is running, check whether the remote connection is blocked by the software. If the remote connection is blocked, add the EIP bound to the ECS to the whitelist of the antivirus software and try to access the ECS again.

You can also disable or uninstall the third-party antivirus software and try to remotely log in to the ECS again.

Checking Whether an Error Occurred During a Remote Login

If an error message is displayed during remote login, check the operation guide based on the error information.

If the fault persists, record the resource details and fault occurred time, and contact technical support for assistance