[Baylisa] DSR load balancer oddities with Ubuntu?

Fri May 10 14:42:56 PDT 2013

Huh. looks like something is unhappy(cksum incorrect?) from what tcpdump is
showing me on the ACK packet back:

Flags [S.], cksum 0x0b22 (incorrect -> 0x2a9b), seq 3623362406, ack
2678610709, win 14480, options [mss 1460,sackOK,TS val 352288 ecr
394642277,nop,wscale 7], length 0

Must have missed some other setting?

On Fri, May 10, 2013 at 1:11 PM, Ray Wong <rayw at rayw.net> wrote:

> Yep, just found it myself, thanks for the nudge in the right direction.
> Unfortunately I seem to have busted it some other way now, so DSR is broken
> entirely. very odd...
>
>
>
> On Fri, May 10, 2013 at 1:07 PM, Ulf Zimmermann <ulf at alameda.net> wrote:
>
>> # Controls source route verification****
>>
>> net.ipv4.conf.default.rp_filter = 0****
>>
>> ** **
>>
>> That is the one  was talking about.****
>>
>> ** **
>>
>> ** **
>>
>> *From:* Anton Cohen [mailto:anton at antoncohen.com]
>> *Sent:* Friday, May 10, 2013 12:54
>> *To:* Ulf Zimmermann
>> *Cc:* Ray Wong; baylisa at baylisa.org
>> *Subject:* Re: [Baylisa] DSR load balancer oddities with Ubuntu?****
>>
>> ** **
>>
>> ** **
>>
>> On Fri, May 10, 2013 at 12:24 PM, Ulf Zimmermann <ulf at alameda.net> wrote:
>> ****
>>
>> Newer Linux kernel have a setting to disallow that. I am not at a
>> computer to look up the sysctl variable but look for something starting
>> with rt or rp.
>>
>> On May 10, 2013, at 12:12, Ray Wong <rayw at rayw.net> wrote:
>>
>> > Well, it sort of has to with DSR, right? :) the traffic hits the BigIP,
>> forwards to the server, and the server replies directly out the router. I'm
>> probably being thickheaded from a long week, do you mean some other sort of
>> pathing?****
>>
>>
>> I think Ulf is right, expect the other way around. You need different
>> return paths and Ubuntu disables them by default [1]. Try disabling return
>> path filtering [2].****
>>
>> ** **
>>
>> [1] https://bugs.launchpad.net/ubuntu/+source/procps/+bug/201952****
>>
>> [2] http://serverfault.com/a/35769/148146****
>>
>
>