vCenter Logins Timeout Quickly

Products

• VMware vCenter Server

Issue/Introduction

Symptoms:

• vCenter GUI/CLI/VAMI is getting logged out within a few seconds.
  • vCenter GUI is getting logged out in approximately 30 seconds.
  • Putty session is getting logged out in approximately 30 seconds.
  • VAMI  is getting logged out in approximately 30 seconds.
  • df -h shows normal output.
  • vCenter was rebooted but issue persists..

• Errors indicating an IP address conflict with another system.
• Frequent logouts or connectivity issues from vCenter, VAMI, or SSH (e.g., PuTTY).

 

Environment

vCenter Server 7.x

vCenter Server 8.x

 

Cause

This issue occurs when two devices on the network are assigned the same IP address, either statically or dynamically. Common causes include:

• Manual misconfiguration of a static IP.
• Another device dynamically assigned the same IP by a DHCP server.

The static IP address that was just configured is already in use on the network.

There is an IP address conflict with another system on the network.

This issue may also occur if the statically assigned IP conflicts with another device using the same IP address.

Resolution

To verify, power off the Vcenter and attempt a ping to the assigned IP address. If replies are received while the Vcenter is powered down, there is a device with the same IP address on the network.

• Verify the IP Address Conflict

a. Power off the vCenter VM or physical server.
b. Open a command prompt or terminal on another device and run the following:

ping <vCenter_IP>

c. If you receive replies while the vCenter is powered off, another device on the network is using the same IP address.

• Identify the Conflicting Device
• Use network tools such as ARP to map the conflicting IP to a MAC address:

arp -a | find "<vCenter_IP>"

• Match the MAC address with known devices on your network or consult your network team.
• Resolve the Conflict
• If the conflicting device is identified:

a. Reconfigure the conflicting device with a unique static IP address.
b. Alternatively, if it’s dynamically assigned, release and renew its IP address.

• If the conflicting device cannot be identified:

a. Assign a new, unique static IP address to the vCenter. Ensure it is outside the DHCP range.
b. Update DNS or relevant configurations to reflect the new IP address.

• Prevent Future Conflicts
• Document and reserve static IP addresses in your DHCP server.
• Audit IP assignments periodically.

Additional Information

• Logs: Check for errors in /var/log/vmware/vpxd/vpxd.log (for vCenter) and /var/log/messages (for the ESXi).
• Connectivity Issues: If you continue to face frequent logouts or network issues, ensure no duplicate IP or DNS mismatches are present.