Masquerading VM works 99%

Slawek Kaplonski skaplons at redhat.com
Tue Feb 15 09:37:48 UTC 2022


Hi,

On piątek, 11 lutego 2022 20:31:24 CET Laurent Dumont wrote:
> You might want to look at port-security if you are using an Openstack VM as
> more of a router. By default, it will permit only it's own mac-address +
> ip-address from exiting the interface.
> 
> You can fully disable it to see if it's the root cause.
> 
>    1. Remove allowed-address-pairs.
>    2. Remove security-groups
>    3. Disable port-security.

It is very likely that the issue is caused by the port security on the 
internal interface of the external vm (where packets are dropped).

> 
> 
> On Thu, Feb 10, 2022 at 11:17 AM Derek O keeffe <derekokeeffe85 at yahoo.ie>
> 
> wrote:
> > Hi all,
> > 
> > We have an openstack cluster with one controller and 4 computes (Victoria)
> > we have set it up using vlan provider networks with linuxbridge agent,
> > distributed routing & ml2 (I am only partly on the networking so there
> > could be more to that which I can find out if needed)

ML2/Linuxbridge don't supports distributed routing (DVR) at all. What do You 
mean by "distributed routing" here?

> > 
> > So I was tasked with creating two Instances, one (lets call it the
> > external vm) with an external interface 10.55.9.67 and internal interface
> > 192.168.1.2. A second instance (lets call it the internal vm) would then 
be
> > placed on the 192.168.1.0 network.
> > 
> > I configured masquerading on the "external vm" and tried to ping the
> > outside world from the "internal" vm as per something like this
> > https://kifarunix.com/configure-ubuntu-20-04-as-linux-router/?unapproved=49
> > 571&moderation-hash=b5168c04420557dcdc088994ffa4bdbb#comment-49571
> > 
> > 
> > Both VM's were instantiated on the same compute host (I've tried it with
> > them on separate hosts as well).
> > 
> > I can see the ping leave using tcpdumps along the way and it makes it all
> > the way back to the internal interface on the external machine. It just
> > fails on the last hop to the internal machine. I've tried everything in my
> > power to find why this won't work so I would be grateful for any advice at
> > all. I have added the below to show how I followed the ping manually and
> > where it went and when it failed. Thank you in advance.
> > 
> > Following the ping from source to destination and back:
> > Generated on the private VM
> > sent to the internal interface on the external vm
> > sent to the external interface on the external vm
> > sent to the tap interface on the compute
> > sent to the physical nic on the compute
> > sent to the nic on the network device out to the internet
> > 
> > received on nic on the network devicefrom the internet
> > received on physical nic on the compute
> > received on tap interface on compute
> > received on external interface on the external vm
> > received on the internal interface on the external vm
> > NEVER gets to last step on the internal vm
> > 
> > Regards,
> > Derek



-- 
Slawek Kaplonski
Principal Software Engineer
Red Hat
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 488 bytes
Desc: This is a digitally signed message part.
URL: <http://lists.openstack.org/pipermail/openstack-discuss/attachments/20220215/697c9680/attachment-0001.sig>


More information about the openstack-discuss mailing list