Date: Thu, 15 Nov 2007 22:18:38 -0800 From: Julian Elischer <julian@elischer.org> To: Brian Hawk <brian@tnetus.com> Cc: freebsd-net@freebsd.org, Dima Dorfman <dd@freebsd.org> Subject: Re: Interface address sourced packets go thru default gateway on another interface Message-ID: <473D363E.20305@elischer.org> In-Reply-To: <473D3258.9040203@tnetus.com> References: <473C5593.4080407@tnetus.com> <20071116001429.GE1499@beaver.trit.net> <473D3258.9040203@tnetus.com>
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Brian Hawk wrote:
> Dima Dorfman wrote:
>> I don't think it ever worked the way you described. The source IP
>> address doesn't usually affect how replies will be routed on the way
>> out.
>>
> Then what would be the reason to bind a connection to a specific source
> address? We do
> ping -S A.B.C.D x.y.z.t
> to make ping send packets to x.y.z.t over A.B.C.D's interface (and
> source address) or
> telnet -s A.B.C.D x.y.z.t
no
binding does not affect the interface the packet goes out.
in affects the address that return packets will be sent to
but that's about all.
>
> I believe binding an IP's source address to an interface address
> (instead of INADDR_ANY) is to make packets go out from *that* interface,
> not the default gw.
>> You can fix this with policy routing rules. Here's an example with PF:
>>
>> : pass out quick route-to ($other_if $other_gw) from ($other_if)
>>
>>
> I really am an ipfilter fan. It's greate that pf support this. But I
> think ipfilter doesn't yet. At least not the version I'm using (v3.4.35).
ipfw can do it with
fwd {next hop} ip from ${other_if} to ${where-ever}
you can even do
fwd tablearg ip from ${src} to table(x) to implement a second routing table
for packets from ${src}
>
> -Brian
>
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