[lvs-users] about NAT return path

Yonghua Peng yhpeng at orange.fr
Mon Feb 2 10:12:57 GMT 2015


Martin,

What I meant is, the incoming packages implement DNAT by LVS, then 
forward to realserver.
The outgoing packages implement SNAT, then forward to client.
Since host A and B have the same VIP (managed by OSPF), after the SNAT, 
the packages seem to be from the same host. Client shouldn't drop them.

Am I right?
Thanks.


  Martin Wheldon wrote:
> Hi,
>
> The DNAT would still need to be reversed. The client will otherwise
> drop
> the packet as it won't be from the host it started the connection with.
>
> Best Regards
>
> Martin
>
> On 2015-02-02 09:59, Yonghua Peng wrote:
>> If it's just a DNAT forwarding for the incoming packet, I don't think
>> LVS host has to keep the status of the connection.
>> I am probably wrong, just by curious. And I will test for it.
>>
>> Thanks.
>>
>> Martin Wheldon wrote:
>>> Hi,
>>>
>>> Because there will be no entry in the NAT table on the second host
>>> so
>>> it won't know how to deal with the return packet.
>>>
>>> Best Regards
>>>
>>> Martin
>>>
>>> On 2015-02-02 09:06, Yonghua Peng wrote:
>>>> Can you tell me why the realserver should use host A as the
>>>> gateway?
>>>> since host A and B have the same configure, and share the same VIP,
>>>> I
>>>> was thinking both A and B can be setup as the gateway.
>>>>
>>>> Thanks.
>>>>
>>>>     Ivan Havlicek wrote:
>>>>> No, if a transaction start via LVS host A, the realserver need to
>>>>> use
>>>>> this host as gateway to respond.
>>>>> This is the normal for a NAT.
>>>>
>>>> _______________________________________________
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>>>>
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>>>>
>>>>
>>>
>>>
>>> _______________________________________________
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>>>
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>>
>> _______________________________________________
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>> http://www.linuxvirtualserver.org/
>>
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>> !DSPAM:31,54cf4a4d101354641921266!
>
>
> _______________________________________________
> Please read the documentation before posting - it's available at:
> http://www.linuxvirtualserver.org/
>
> LinuxVirtualServer.org mailing list - lvs-users at LinuxVirtualServer.org
> Send requests to lvs-users-request at LinuxVirtualServer.org
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