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

**URL:** <https://discuss.elastic.co/t/es-5-2-0-in-kvm-netty-warning-failed-to-find-a-usable-hardware-address-from-the-network-interfaces/73717>\
**Category:** Elasticsearch\
**Created:** [February 2, 2017, 4:23pm UTC](https://discuss.elastic.co/t/es-5-2-0-in-kvm-netty-warning-failed-to-find-a-usable-hardware-address-from-the-network-interfaces/73717 "2017-02-02T16:23:36Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![fciocchetti](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/fciocchetti/32/13368_2.png) [@fciocchetti](https://discuss.elastic.co/u/fciocchetti)\
**Post date:** [February 2, 2017, 4:23pm UTC](https://discuss.elastic.co/t/es-5-2-0-in-kvm-netty-warning-failed-to-find-a-usable-hardware-address-from-the-network-interfaces/73717/1 "2017-02-02T16:23:36Z")

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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](https://github.com/netty/netty/issues/3490) 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 ?

Thanks

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**Author:** ![kkircher805](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/kkircher805/32/14980_2.png) [@kkircher805](https://discuss.elastic.co/u/kkircher805)\
**Post date:** [February 3, 2017, 1:22am UTC](https://discuss.elastic.co/t/es-5-2-0-in-kvm-netty-warning-failed-to-find-a-usable-hardware-address-from-the-network-interfaces/73717/2 "2017-02-03T01:22:23Z")

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

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**Author:** ![jasontedor](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jasontedor/32/66992_2.png) [@jasontedor](https://discuss.elastic.co/u/jasontedor)\
**Post date:** [February 3, 2017, 1:56am UTC](https://discuss.elastic.co/t/es-5-2-0-in-kvm-netty-warning-failed-to-find-a-usable-hardware-address-from-the-network-interfaces/73717/3 "2017-02-03T01:56:26Z")

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> [@fciocchetti](#):
>
> Does anyone know what this is ?

It was introduced by this change in Netty: [Fix DefaultChannelId MAC address parsing bug by Scottmitch · Pull Request #6147 · netty/netty · GitHub](https://github.com/netty/netty/pull/6147/)

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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<div class="post-metadata">

**Author:** ![jasontedor](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jasontedor/32/66992_2.png) [@jasontedor](https://discuss.elastic.co/u/jasontedor)\
**Post date:** [February 3, 2017, 1:57am UTC](https://discuss.elastic.co/t/es-5-2-0-in-kvm-netty-warning-failed-to-find-a-usable-hardware-address-from-the-network-interfaces/73717/4 "2017-02-03T01:57:03Z")

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> [@kkircher805](#):
>
> I am having the same problem, but elasticsearch immediately quits. Only will startup if I have the default for network.host

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.

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<div class="post-metadata">

**Author:** ![jasontedor](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jasontedor/32/66992_2.png) [@jasontedor](https://discuss.elastic.co/u/jasontedor)\
**Post date:** [February 3, 2017, 2:19am UTC](https://discuss.elastic.co/t/es-5-2-0-in-kvm-netty-warning-failed-to-find-a-usable-hardware-address-from-the-network-interfaces/73717/5 "2017-02-03T02:19:23Z")

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I opened [https://github.com/netty/netty/pull/6308](https://github.com/netty/netty/pull/6308) against Netty.

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [March 3, 2017, 2:19am UTC](https://discuss.elastic.co/t/es-5-2-0-in-kvm-netty-warning-failed-to-find-a-usable-hardware-address-from-the-network-interfaces/73717/6 "2017-03-03T02:19:34Z")

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