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Date:      Tue, 10 Mar 2015 23:53:09 +0900
From:      "Paul S." <contact@winterei.se>
To:        freebsd-net@freebsd.org
Subject:   Re: FreeBSD responding with wrong receiving interface IP
Message-ID:  <54FF0555.9070901@winterei.se>
In-Reply-To: <54FF0266.3080106@m.jwh.me.uk>
References:  <54FE566F.5030607@winterei.se> <B70E1152-E492-4B38-B2EE-A5DBF246DEF7@neville-neil.com> <54FF0266.3080106@m.jwh.me.uk>

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Joe,

That was it, thank you! I looked over net.inet.ip and ip6, icmp never 
crossed my mind.

George, thank you as well.

On 3/10/2015 午後 11:40, Joe Holden wrote:
> On 10/03/2015 13:16, George Neville-Neil wrote:
>> On 10 Mar 2015, at 11:26, Paul S. wrote:
>>
>>> Hi,
>>>
>>> I've been deploying FreeBSD as customer edge routers for customers
>>> with sites that do not require high throughput (>1g/s).
>>>
>>> Each site has two ISPs (Mostly Telstra + Verizon/Optus), and take full
>>> routes via OpenBGPd and BIRD. I use next-hop self on all received 
>>> routes.
>>>
>>> The FreeBSD boxes have static routes delegating the announced IP
>>> blocks to a L3 switch down the road. i.e: route add -net 10.100.1.0/24
>>> 10.0.0.1, and then that /24 is originated via BGP to both upstreams.
>>>
>>> Things in general work fine, but I've been receiving reports of 'weird
>>> traceroute results' from my customers.
>>>
>>> Examples of this would be,
>>>
>>> 1 some.random.isp (...) (...)
>>> 2  gigabitethernet3-3.exi1.melbourne.telstra.net (203.50.77.49) 0.309
>>> ms  0.284 ms  0.227 ms
>>> 3  bundle-ether3-100.exi-core10.melbourne.telstra.net (203.50.80.1)
>>> 1.966 ms  1.675 ms  1.852 ms
>>> 4  bundle-ether12.chw-core10.sydney.telstra.net (203.50.11.124) 16.707
>>> ms  15.917 ms  16.360 ms
>>> 5  customer-gw.syd.ALTER.net (...) (...)
>>>
>>> This traceroute seems to claim that the packet was received over the
>>> Verizon gateway, which in reality it was not -- it was received
>>> directly over the Telstra interface, but my outbound AS-PATH towards
>>> some.random.isp uses Verizon.
>>>
>>> So FreeBSD replies back with the Verizon address. Another person
>>> having the same issue (mostly, but on OpenBSD) can be found at
>>> http://openbsd.7691.n7.nabble.com/BGP-responding-with-wrong-IP-address-td90264.html 
>>>
>>>
>>>
>>> I would love to know if there's a way to fix this, or if I've missed
>>> something, or if there's something wrong in the way I set it up.
>>>
>>> Thank you for taking the time to read.
>>
>> I wonder if we could see some routing tables?  That might help.
>>
>> Best,
>> George
>
> sysctl net.inet.icmp.reply_from_interface=1 will probably do what you 
> expect.
>
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