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________________________________
From: Carl Baldwin [carl at ecbaldwin.net]
Sent: Monday, June 30, 2014 3:43 AM
To: OpenStack Development Mailing List
Subject: Re: [openstack-dev] DVR and FWaaS integration

On Mon, Jun 30, 2014 at 3:43 AM, Carl Baldwin <carl at ecbaldwin.net<mailto:carl at ecbaldwin.net>> wrote:

In line...

On Jun 25, 2014 2:02 PM, "Yi Sun" <beyounn at gmail.com<mailto:beyounn at gmail.com>> wrote:
>
> All,
> During last summit, we were talking about the integration issues between DVR and FWaaS. After the summit, I had one IRC meeting with DVR team. But after that meeting I was tight up with my work and did not get time to continue to follow up the issue. To not slow down the discussion, I'm forwarding out the email that I sent out as the follow up to the IRC meeting here, so that whoever may be interested on the topic can continue to discuss about it.
>
> First some background about the issue:
> In the normal case, FW and router are running together inside the same box so that FW can get route and NAT information from the router component. And in order to have FW to function correctly, FW needs to see the both directions of the traffic.
> DVR is designed in an asymmetric way that each DVR only sees one leg of the traffic. If we build FW on top of DVR, then FW functionality will be broken. We need to find a good method to have FW to work with DVR.
>
> ---forwarding email---
>  During the IRC meeting, we think that we could force the traffic to the FW before DVR. Vivek had more detail; He thinks that since the br-int knowns whether a packet is routed or switched, it is possible for the br-int to forward traffic to FW before it forwards to DVR. The whole forwarding process can be operated as part of service-chain operation. And there could be a FWaaS driver that understands the DVR configuration to setup OVS flows on the br-int.

I'm not sure what this solution would look like.  I'll have to get the details from Vivek.  It seems like this would effectively centralize the traffic that we worked so hard to decentralize.

It did cause me to wonder about something:  would it be possible to reign the symmetry to the traffic by directing any response traffic back to the DVR component which handled the request traffic?  I guess this would require running conntrack on the target side to track and identify return traffic.  I'm not sure how this would be inserted into the data path yet.  This is a half-baked idea here.

> The concern is that normally firewall and router are integrated together so that firewall can make right decision based on the routing result. But what we are suggesting is to split the firewall and router into two separated components, hence there could be issues. For example, FW will not be able to get enough information to setup zone. Normally Zone contains a group of interfaces that can be used in the firewall policy to enforce the direction of the policy. If we forward traffic to firewall before DVR, then we can only create policy based on subnets not the interface.
> Also, I’m not sure if we have ever planed to support SNAT on the DVR, but if we do, then it depends on at which point we forward traffic to the FW, the subnet may not even work for us anymore (even DNAT could have problem too).

I agree that splitting the firewall from routing presents some problems that may be difficult to overcome.  I don't know how it would be done while maintaining the benefits of DVR.

Another half-baked idea:  could multi-primary state replication be used between DVR components to enable firewall operation?  Maybe work on the HA router blueprint -- which is long overdue to be merged Btw -- could be leveraged.  The number of DVR "pieces" could easily far exceed that of active firewall components normally used in such a configuration so there could be a major scaling problem.  I'm really just thinking out loud here.

Maybe you (or others) have other ideas?

I think ovs based firewall may resolve the conflict between "distributed" and "stateful". Redirect response traffic from ovs to iptable will bring a lot of challenge, such as how to restore source mac when traffic return to br-int from iptable.


In the future, security group and fwaas should be merged, present to user a unified firewall API.


>
> --- end of forwarding ----
>
> YI
>
>
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