[Openstack-operators] [neutron] Instances on private net can't resolve, no DNS

Christopher Hull chrishull42 at gmail.com
Thu Mar 31 16:43:09 UTC 2016


Hello all;

Here's my problem.    Instances on the Public net work perfectly.
Instances on the Private network can fully access other instances on both
the Public and Private networks ICMP/TCP/UDP.  They can ping IP addresses
on the internet.  But no TCP / UDP it seems.

>From the perspective of the Private net, what is the difference between the
Public net and the internet?

deas?

Chris


- Christopher T. Hull
I am presently seeking a new career opportunity  Please see career page
http://chrishull.com/career
333 Orchard Ave, Sunnyvale CA. 94085
(415) 385 4865
chrishull42 at gmail.com
http://chrishull.com



On Thu, Mar 31, 2016 at 6:54 AM, Christopher Hull <chrishull42 at gmail.com>
wrote:

> Hi James / all
>
> DNS is a red herring...
>
> From the private net, I can now ping any IP.   The northbound router
> Neutron Port is up.  So those are improvements as a result of the update.
> But I can't telnet to any IP / port from an instance on the private net.
> It shouldn't be Demo's security group settings as a Demo instance can do
> anything from the public net.  Looks like the Neutron Router still isn't
> working.
>
> Updated Neutron by hand.   Just noticed the CentOS Openstack repo has been
> updated as of last Tuesday.  Run yum update.  "No packages marked for
> update", so I suspect I'm finally running the latest Neutron at least.
> Any more bug fixes related to this that anyone knows of?   Guess I'll check
> the error logs again.
>
> -Chris
>
>
>
> - Christopher T. Hull
> I am presently seeking a new career opportunity  Please see career page
> http://chrishull.com/career
> 333 Orchard Ave, Sunnyvale CA. 94085
> (415) 385 4865
> chrishull42 at gmail.com
> http://chrishull.com
>
>
>
> On Wed, Mar 30, 2016 at 10:04 PM, <chrishull42 at gmail.com> wrote:
>
>> Hi James.
>>
>> That makes sense.   I had tried that.  Doesn't seem to work.   I'd think
>> the public and private subnets would behave the same way.  Public works but
>> private doesn't.   Private can ping though
>>
>> Telnet can't get to port 53 from an instance on the private net.
>>
>> Public net can use my ATT router gateway as DNS too.
>>
>> Wondering if Neutron router is to blame... again.  :)
>>
>> Thanks
>> Chris.
>>
>> Sent from my iPhone
>>
>> On Mar 30, 2016, at 9:20 PM, James Denton <james.denton at rackspace.com>
>> wrote:
>>
>> Hi Chris,
>>
>>
>> It shouldn't be as complex as that. DNS nameservers are pushed to
>> instances via DHCP, and those name servers are set during subnet creation.
>> You can also do a 'neutron subnet-update' to update an existing subnet.
>>
>>
>> Syntax:
>>
>> neutron subnet-update <subnet> --dns-nameservers <dns1> <dns2>
>>
>>>>
>> That would be used to update the subnet your instances attach to and not
>> the external subnet attached to the router. Hope that helps.
>>
>>
>> James
>>
>>
>>
>> ------------------------------
>> *From:* Christopher Hull <chrishull42 at gmail.com>
>> *Sent:* Wednesday, March 30, 2016 11:06 PM
>> *To:* openstack-operators
>> *Subject:* [Openstack-operators] [neutron] Instances on private net
>> can't resolve, no DNS
>>
>> Hello all;
>>
>> Well, more pulling of teeth it seems before I actually get to USE my
>> self-installed OpenStack Liberty.  :-)
>>
>> All networks seem to work just fine.  Can ping everything from private
>> network.  You would think DNS would work, but it doesn't    This I think
>> has something to do with dnsmasq.
>>
>> I've read a few web pages.   Set dnsmasq_dns_servers in dhcp_agent.ini to
>> 8.8.8.8,8.8.4.4 (Google DNS).   Also set the private subnet to those.
>> Nada.
>>
>> From within an instance on the Private network, telnet 8.8.8.8 53 "no
>> route to host".... but it PINGS!   Hmmm.
>>
>> So help me unravel more of this genome known as OpenStack.  Why if
>> private instances can reach the internet, doens't DNS work????
>>
>> Just patched Neutron to fix the previous bug.  I think I have the latest.
>>
>> Thanks
>> -Chris
>>
>>
>> - Christopher T. Hull
>> I am presently seeking a new career opportunity  Please see career page
>> http://chrishull.com/career
>> 333 Orchard Ave, Sunnyvale CA. 94085
>> (415) 385 4865
>> chrishull42 at gmail.com
>> http://chrishull.com
>>
>>
>>
>
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