vSphere HA is enhanced by several security features.

Select firewall ports opened

vSphere HA uses TCP and UDP port 8182 for agent-to-agent communication. The firewall ports open and close automatically to ensure they are open only when needed.

Configuration files protected using file system permissions

vSphere HA stores configuration information on the local storage or on ramdisk if there is no local datastore. These files are protected using file system permissions and they are accessible only to the root user.

Detailed logging

The location where vSphere HA places log files depends on the version of host.

For ESXi 5.x hosts, vSphere HA writes to syslog only by default, so logs are placed where syslog is configured to put them. The log file names for vSphere HA are prepended with fdm, fault domain manager, which is a service of vSphere HA.

For legacy ESXi 4.x and 3.x hosts, vSphere HA writes to /var/log/vmware/fdm on local disk, as well as syslog if it is configured.

For legacy ESX 4.x and 3.x hosts, vSphere HA writes to /var/log/vmware/fdm.

Secure vSphere HA logins

vSphere HA logs onto the vSphere HA agents using a user account, vpxuser, created by vCenter Server. This account is the same account used by vCenter Server to manage the host. vCenter Server creates a random password for this account and changes the password periodically. The time period is set by the vCenter Server VirtualCenter.VimPasswordExpirationInDays setting. You can change the setting using the Advanced Settings control in the vSphere Client. Users with administrative privileges on the root folder of the host can also log in to the agent.

Secure communication

All communication between vCenter Server and the vSphere HA agent is done over SSL. Agent-to-agent communication also uses SSL except for election messages, which occur over UDP. Election messages are verified over SSL so that a rogue agent can prevent only the host on which the agent is running from being elected as a master host. In this case, a configuration issue for the cluster is issued so the user is aware of the problem.

Host SSL certificate verification required

vSphere HA requires that each host have a verified SSL certificate. Each host generates a self-signed certificate when it is booted for the first time. This certificate can then be regenerated or replaced with one issued by an authority. If the certificate is replaced, vSphere HA needs to be reconfigured on the host. If a host becomes disconnected from vCenter Server after its certificate is updated and the ESXi or ESX Host agent is restarted, then vSphere HA is automatically reconfigured when the host is reconnected to vCenter Server. If the disconnection does not occur because vCenter Server host SSL certificate verification is disabled at the time, verify the new certificate and reconfigure vSphere HA on the host.