netdev - Re: Fwd: LVS on local node

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Message-ID: <AANLkTimLZG_-4wbKy8nrajHVKQvvGtRKEd8qHNoU3swJ@mail.gmail.com>
Date:	Thu, 22 Jul 2010 17:52:35 +0800
From:	Changli Gao <xiaosuo@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Patrick McHardy <kaber@...sh.net>,
	Jan Engelhardt <jengelh@...ozas.de>,
	Franchoze Eric <franchoze@...dex.ru>, wensong@...ux-vs.org,
	lvs-devel@...r.kernel.org, netdev@...r.kernel.org,
	netfilter-devel@...r.kernel.org
Subject: Re: Fwd: LVS on local node

On Thu, Jul 22, 2010 at 5:46 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> Le jeudi 22 juillet 2010 à 17:10 +0800, Changli Gao a écrit :
>
>>
>> I think maybe REDIRECT is enough. If the public port is one of the
>> real ports, you need to append "random" option to iptables target
>> REDIRECT. If not, "REDIRECT --to-ports 1000-1007" is good enough, and
>> the destination port will be selected in the round-robin manner.
>>
>
> Yes, on 2.6.32, no RPS, so undocumented --random option is probably the
> best we can offer. (random option was added in 2.6.22)
>
> iptables -t nat -A PREROUTING -p tcp --dport 1234 -j REDIRECT --random --to-port 1000-1007
>
> Here is a patch to add "random" help to REDIRECT iptables target
>

FYI: the random option is documented in the manual page of iptables.

   REDIRECT
       This  target is only valid in the nat table, in the PREROUTING and OUT-
       PUT chains, and user-defined chains which are only  called  from  those
       chains.   It redirects the packet to the machine itself by changing the
       destination IP  to  the  primary  address  of  the  incoming  interface
       (locally-generated packets are mapped to the 127.0.0.1 address).

       --to-ports port[-port]
              This  specifies  a  destination  port  or range of ports to use:
              without this, the destination port is never  altered.   This  is
              only valid if the rule also specifies -p tcp or -p udp.

       --random
              If  option --random is used then port mapping will be randomized
              (kernel >= 2.6.22).


-- 
Regards,
Changli Gao(xiaosuo@...il.com)
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