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Contributor
Posts: 30
Registered: ‎10-27-2015
Accepted Solution

Disabling IPv6

In a recent Predictive Cluster Validation Summary for one of my clusters, Cloudera Proactive Support states:

 

"The following hosts have IPv6 enabled, which is against our best practices, because it can cause connectivity problems. This is discussed in the CDH documentation. (http://www.cloudera.com/content/cloudera/en/documentation/core/latest/topics/cdh_ig_req_supported_ve..."

 

Yet that page simply says that "IPv6 is not supported and must be disabled."

 

If this is a hard requirement, then why is there no documentation on *how* to disable IPv6 for the various supported OSs?  I understand that Cloudera may not want to get into the OS configuration business, but at least pointers to vender documentation should be provided.

 

Posts: 713
Topics: 1
Kudos: 165
Solutions: 89
Registered: ‎04-22-2014

Re: Disabling IPv6

Hello @mjarnold,

 

Thank you for pointing that out.  I have added this post to internal Cloudera Jira DOCS-1862 where we are discussing documentation.

 

Regards,

 

Ben

Cloudera Employee
Posts: 13
Registered: ‎06-25-2014

Re: Disabling IPv6

Thank you Ben.

Contributor
Posts: 30
Registered: ‎10-27-2015

Re: Disabling IPv6

Hey @bgooley,

 

Is there any update on DOCS-1862?

Cloudera Employee
Posts: 13
Registered: ‎06-25-2014

Re: Disabling IPv6

Hi @mjarnold, I can comment on this on behalf of Ben. The docs received a minor improvement that advises the OS vendor to be contacted for complete information or any necessary assistance regarding disabling ipv6:

Networking Protocols Support
CDH requires IPv4. IPv6 is not supported and must be disabled.
Note: Contact your OS vendor for help disabling IPv6.

This was the resulting improvement in the docs stemming from the jira I filed after we first spoke about this issue. I know this isn’t much of a change, but we felt it was the most sound advice we could provide on the next-steps necessary.

If you have any feedback please do let us know. We sincerely appreciate your long-running excellent partnership here with us in Cloudera Support.

Best,
Alex
Contributor
Posts: 30
Registered: ‎10-27-2015

Re: Disabling IPv6

@Alex,

 

I am curious as to what the Proactive Support tests look for when testing whether IPv6 is enabled.  Is it the existence of IPv6 addresses on interfaces or the presence of the IPv6 kernel module?

 

Red Hat's solutions indicate that you can either disable the kernel module via kernel boot options (results in other things breaking) or disable IPv6 on network interfaces via sysctl.  Debian appears to be similar.

 

Cloudera Employee
Posts: 13
Registered: ‎06-25-2014

Re: Disabling IPv6

Hi Michael,

 

Based on what I see in the script/code, it's the presence of inet6 in the ifconfig output, which is included in the diagnostic bundle. If inet6 is present and in use, I believe that's the basis for the alert that was issued.

 

Best,

Alex

Contributor
Posts: 30
Registered: ‎10-27-2015

Re: Disabling IPv6

Thanks.  It sounds like the following should suffice:

 

sysctl -w net.ipv6.conf.all.disable_ipv6=1

sysctl -w net.ipv6.conf.default.disable_ipv6=1

 

Cloudera Employee
Posts: 13
Registered: ‎06-25-2014

Re: Disabling IPv6

Completely agreed sir. +1

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