2020-01-04 15:52:48

by Jon Masters

[permalink] [raw]
Subject: nf_nat not running in a netns

Hi there,

Can anyone offer any reasons why the nat table chains for a netns wouldn’t be running?

Longer detail:

I’ve be playing with Kolla (containerized OpenStack) and the way they implement (virtual) routers for tenant networks is to create network namespaces with interfaces representing the ports plugged into the router. To translate addresses from internal to external networks, they apply D/SNAT rules within that netns. All of these are created and the interfaces are pingable, but the nat rules aren’t being run and the untranslated addresses are ultimately seen on the physical network once packets traverse out of the containers and to the external neutron interface.

Jon.

--
Computer Architect


2020-01-05 18:59:39

by Jon Masters

[permalink] [raw]
Subject: Re: nf_nat not running in a netns

Ignore. The below was exactly the problem.

It was broken. netns nat rules in CentOS7.7 kernel were exactly not working due to a bug. Sigh.

--
Computer Architect


> On Jan 4, 2020, at 10:51, Jon Masters <[email protected]> wrote:
>
> Hi there,
>
> Can anyone offer any reasons why the nat table chains for a netns wouldn’t be running?
>
> Longer detail:
>
> I’ve be playing with Kolla (containerized OpenStack) and the way they implement (virtual) routers for tenant networks is to create network namespaces with interfaces representing the ports plugged into the router. To translate addresses from internal to external networks, they apply D/SNAT rules within that netns. All of these are created and the interfaces are pingable, but the nat rules aren’t being run and the untranslated addresses are ultimately seen on the physical network once packets traverse out of the containers and to the external neutron interface.
>
> Jon.
>
> --
> Computer Architect
>