Open Stack

If I understood correctly, you talk about rules which are generated by
security_group extension as default from the fixed_ips +
allowed_address_pairs list. In our openstack installation we disabled the
security_group and the allowed_address_pairs extensions to simplify the
configuration the HA clusters.

Currently we configure the neutron as follows:
1. prevent_arp_spoofing = False
2. disable security_group extension
3. disable allowed_address_pairs extension

Actually, if port_security will be like a "central regulator" which
controll all mechanisms, it's perfectly in our case. But, we will lose
flexibility, because we can't changed default value for this option. And,
even if we disable the port_security extension in the neutron, the prevent
ARP-spoofing mechanism will work as default [1].

It's very important question, how do we may disable globally the prevent
ARP spoofing in the Pike release? To create all networks without specifying
an option port_security_enabled=False.

Changes that were proposed by Tatiana, just let save current flexability.

[1]
https://github.com/openstack/neutron/blob/stable/pike/neutron/plugins/ml2/drivers/openvswitch/agent/ovs_neutron_agent.py#L907

2018-03-19 16:24 GMT+03:00 Kevin Benton <kevin at benton.pub>:

> Disabling ARP spoofing protection alone will not let the standby instance
> source traffic using the active instance's IP. IP filtering rules
> independent of ARP enforcement rules ensure the source IP is in the
> fixed_ips or allowed_address_pairs.
>
> Are you already using allowed address pairs to add the shared IP to both?
>
> On Mon, Mar 19, 2018, 22:13 Vadim Ponomarev <ponomarev at selectel.ru> wrote:
>
>> Yes, there's really a need for mechanisms of high availability like
>> corosync, vrrp etc. Another simple example: we have two servers with the
>> active/standby HA configuration  (for example keepalived + haproxy) and we
>> have third-party monitoring system for these servers. The monitoring system
>> gets some load metrics and when one of the servers is unavailable, the
>> monitoring system scales architecture (adds new server to cluster) in this
>> way saving the HA architecture. In your case, this monitoring system must
>> do the following steps: create new instance, add new instance's MAC address
>> to allowed_address_pairs and only after that reconfigure all other nodes.
>> Otherwise cluster will not work. The solution to the problem is simple -
>> disable the prevent ARP spoofing mechnism.
>>
>> Ok, we may used port_security options for this network with the HA
>> cluster. For this case we must reconfigure our monitoring systems, create
>> allowed_address_pairs for all current servers and (it's hardest) train our
>> users how that done.
>>
>> Currently, we don't use the prevent ARP spoofing option
>> (prevent_arp_spoofing = False) and honestly I don't understand why this
>> option is enabled as default in private networks. Each such network belongs
>> to one user, who controls all instances. Who would decide to perform a MITM
>> attack in his own network?
>>
>> 2018-03-19 12:53 GMT+03:00 Kevin Benton <kevin at benton.pub>:
>>
>>> Do you need to spoof arbitrary addresses? If not (i.e. a set you know
>>> ahead of time), you can put entries in the allowed_address_pairs field of
>>> the port that will allow you to send traffic using other MAC/IPs.
>>>
>>> On Mar 19, 2018 8:42 PM, "Vadim Ponomarev" <ponomarev at selectel.ru>
>>> wrote:
>>>
>>> Hi,
>>>
>>> I support, that is a problem. It's unclear, how after removing the
>>> option prevent_arp_spoofing, I can manage the prevent ARP spoofing
>>> mechanism. Example: I use security groups but I don't want to use ARP
>>> spoofing protection. How do I can disable the protection?
>>>
>>> 2018-03-14 10:26 GMT+03:00 Tatiana Kholkina <holkina at selectel.ru>:
>>>
>>>> Sure, there is an ability to enable ARP spoofing for the port/network,
>>>> but it is impossible to make it enabled by default for all ports.
>>>> It looks a bit complicated to me and I think it would be better to have
>>>> an ability to set default port security via config file.
>>>>
>>>> Best regards,
>>>> Tatiana
>>>>
>>>> 2018-03-13 15:10 GMT+03:00 Claudiu Belu <cbelu at cloudbasesolutions.com>:
>>>>
>>>>> Hi,
>>>>>
>>>>> Indeed ARP spoofing is prevented by default, but AFAIK, if you want it
>>>>> enabled for a port / network, you can simply disable the security groups on
>>>>> that neutron network / port.
>>>>>
>>>>> Best regards,
>>>>>
>>>>> Claudiu Belu
>>>>>
>>>>> ------------------------------
>>>>> *From:* Татьяна Холкина [holkina at selectel.ru]
>>>>> *Sent:* Tuesday, March 13, 2018 12:54 PM
>>>>> *To:* openstack-dev at lists.openstack.org
>>>>> *Subject:* [openstack-dev] [neutron] Prevent ARP spoofing
>>>>>
>>>>> Hi,
>>>>> I'm using an ocata release of OpenStack where the option
>>>>> prevent_arp_spoofing can be managed via conf. But later in pike it was
>>>>> removed and it was decided to prevent spoofing by default.
>>>>> There are cases where security features should be disabled. As I can
>>>>> see now we can use a port_security option for these cases. But this option
>>>>> should be set for a particular port or network on create. The default value
>>>>> is set to True [1] and itt is impossible to change it. I'd like to
>>>>> suggest to get default value for port_security [2] from config option.
>>>>> It would be nice to know your opinion.
>>>>>
>>>>> [1] https://github.com/openstack/neutron-lib/blob/
>>>>> stable/queens/neutron_lib/api/definitions/port_security.py#L21
>>>>> [2] https://github.com/openstack/neutron/blob/stable/
>>>>> queens/neutron/objects/extensions/port_security.py#L24
>>>>>
>>>>> Best regards,
>>>>> Tatiana
>>>>>
>>>>> ____________________________________________________________
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>>>>>
>>>>
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>>>
>>>
>>> --
>>> Best regards,
>>> Vadim Ponomarev
>>> Developer of network automation department at Selectel Ltd.
>>>
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>> --
>> Best regards,
>> Vadim Ponomarev
>> Developer of network automation department at Selectel Ltd.
>>
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-- 
Best regards,
Vadim Ponomarev
Developer of network automation department at Selectel Ltd.

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