Re: [lvs-users] LVS-DR on default gateway

To: "Dennis J." <dennisml@xxxxxxxxxxxx>
Subject: Re: [lvs-users] LVS-DR on default gateway
Cc: lvs-users@xxxxxxxxxxxxxxxxxxxxxx
From: Julian Anastasov <ja@xxxxxx>
Date: Thu, 21 Jan 2010 23:05:47 +0200 (EET)

On Thu, 21 Jan 2010, Dennis J. wrote:

> Hm, I tried setting /proc/sys/net/ipv4/conf/*/rp_filter all both to 0 and 
> to 1 but that had no effect.
> According to this link one cannot control this behaviour using rp_filter:
> The forward_shared patch apparently changes this but I'm wondering why this 
> hasn't been accepted into the mainline kernel yet after all these years. 
> The patch seems to be simple enough. I'd really like to use the LVS-DR 
> approach but I had hoped that either this or a similar patch had moved 
> upstream by now so one could simply tell the kernel to accept these 
> packets. Isn't this what the rp_filter flags are for after all?

        It is too dangerous rp_filter to control such
packets because by default rp_filter is OFF. But we should
not worry anymore because more relaxed version of forward_shared
was accepted in kernel:;a=commit;h=8153a10c08f1312af563bb92532002e46d3f504a

        It is from Patrick McHardy (ipv4: add sysctl to accept packets 
with local source addresses) and adds "accept_local" flag
in /proc/sys/net/ipv4/conf/... It uses OR logic:

all/accept_local || <dev>/accept_local

        of course, all/accept_local=1 is dangerous to use
for hosts visible from world. So, <dev>/accept_local=1 is
enough to accept traffic from internal device (with real
servers in the IPVS case).


Julian Anastasov <ja@xxxxxx>

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