What is the command to flash a NIC link light?

Solution 1:

Yeah it was ethtool I was looking for but specifically this will flash the link light for two minutes:

ethtool -p eth0 120

Is ethtool what you're looking for

ethtool --identify eth0

Ethtool also works with vmware ESXi with -p parameter:

Example: ethtool -p vmnic0 15

vmnic0 will blink for 15 seconds

Here is a video that shows how it works (at 2:50 shows blink):

http://www.sysadmit.com/2017/06/vmware-esxi-vmnic-nic-fisica.html