NTP – ntpdate works but does not update system time

Today I got a wired issue on AWS RHEL servers, ntpdate can’t update the time on it.

ntpdate can find out the time difference, but do not update system time.

And I did some research and found out this issue was caused by Wallclock Setting.

Below are the solutions for this issue:

0 means that the virtual machine is getting time from the host and not using independent wallclock.
1 means that the virtual machine is using independent wallclock and managing its time independent from the host.

Permanently Changing the Independent Wallclock Setting

Log in to the virtual machine environment as root.

Edit the virtual machine’s /etc/sysctl.conf file.
Add or change the following entry:

Enter 1 to enable or 0 to disable the wall clock settting.
Save the file and reboot the virtual machine operating system.

When it boots, a virtual machine gets its initial clock time from the host. Then, if the wallclock setting is set to 1 in the sysctl.conf file, it manages its clock time independently and does not synchronize with the host clock time.

Temporarily Changing the Independent Wallclock Setting

Log in to the virtual machine environment as root.
Enter the following command:

Enter 1 to enable or 0 to disable the wall clock settting.

Add or change the following entry:

Enter 1 to enable or 0 to disable the wall clock settting.
 

Ethernet address: ‘*’. It conflicts with VMware reserved MACs.

After manually modified the MAC address of a VM, got below error when try to power on the VM:

Ethernet address: ‘*’. It conflicts with VMware reserved MACs.

The solution is to modify the VMX file manually, and add below line:

ethernetN.checkMACAddress = “false”
ethernetN.addressType = “static”

ESXi 5.x and 6.x firewall Management command

esxcli network firewall get Returns the enabled or disabled status of the firewall and lists default actions.
esxcli network firewall set –default-action Update default actions.
esxcli network firewall set –enabled Set to true to enable the firewall, set to false to disable the firewall.
esxcli network firewall load Load the firewall module and rule set configuration files.
esxcli network firewall refresh Refresh the firewall configuration by reading the rule set files if the firewall module is loaded.
esxcli network firewall unload Destroy filters and unload the firewall module.
esxcli network firewall ruleset list List rule sets information.
esxcli network firewall ruleset set –allowedall Set the allowedall flag.
esxcli network firewall ruleset set –enabled Enable or disable the specified rule set.
esxcli network firewall ruleset allowedip list List the allowed IP addresses of the specified rule set.
esxcli network firewall ruleset allowedip add Allow access to the rule set from the specified IP address or range of IP addresses.
esxcli network firewall ruleset allowedip remove Remove access to the rule set from the specified IP address or range of IP addresses

Citrix Netscaler VPX high CPU usage? almost 100%

I’m running a Citrix Netscaler VPX in my lab, and I just noticed that even though there is no connection, the CPU usage for this VPX is 100%.

You can change this behavior by doing the following:

On the left, go to System > Settings.

On the right, in the bottom of the second column, click Change VPX Configuration Settings.

Change the CPU Yield drop-down to YES, and click OK.

After making this change, you can see an immediate drop-off in CPU consumption.

Remove 3D Objects from This PC’s Folders and File Explorer Navigation Pane (Windows 10 update 1079)

delete below two key from regedit