ES 5.2.0 in KVM - Netty Warning : Failed to find a usable hardware address from the network interfaces

I just upgraded my test cluster from 5.1.2 to 5.2 and i can see a "new warning" in my logs, i think is from Netty (which was upgraded from 4.1.6 to 4.1.7 according to docs)

[2017-02-02T14:46:48,481][WARN ][i.n.u.i.MacAddressUtil   ] Failed to find a usable hardware address from the network interfaces; using random bytes: 85:6d:c7:97:c3:fa:6d:3b

This will repeat every time i start elasticsearch selecting a different random address.

Of course i do have a valid mac address

# ifconfig eth0 | egrep ^eth0
eth0      Link encap:Ethernet  HWaddr 52:54:00:F9:32:BD

The only reference i was able to find to this issue is for Netty 4.1.0 beta , and it should be fixed in 4.1.7

Everything seems to be working fine though. not only my cluster looks good but tcpdump show the correct mac address , the interface one rather than the random one, for port 9300.

Before i consider to upgrade my live clusters though i need to understand if this is an issue in any way and what is causing it.

Does anyone know what this is ?
Is it new in 5.2.0 or did i simply miss it / not log it before ?


I am having the same problem, but elasticsearch immediately quits. Only will startup if I have the default for

It was introduced by this change in Netty:

Your MAC address is considered locally-administered address (because it starts with 0x52 -> the second-least significant bit is not zero) and therefore is not considered a good candidate (by Netty) for the "best" MAC address.

This is not a serious issue, these are just used to label channel IDs that appear in debug statements.

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No, I think you're having a different problem. It sounds to me like you're failing a bootstrap check. Check the tail of the logs for failing bootstrap checks and open a new topic if you need help.

I opened against Netty.

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