Eric at on 17 Feb 2012 06:52:31 -0800

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Re: [PLUG] network choice from the application level

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Thanks for the suggestions - I'm just going to have them do something else.
I have a big lever... they want the site up ASAP.


On 02/17/2012 09:21 AM, Matt Mossholder wrote:
> On Thu, Feb 16, 2012 at 10:09 PM, Eric at <> wrote:
>> Hash: SHA1
>> Suppose:
>> 1. I have two applications running on an OpenSuse server.
>> 2. This OpenSuse server has one NIC and two IP addresses.
>> 3. There is a database server in the same network
>>   that has a *single* IP address.
>> Is it possible for the applications (PHP) to select which of the two
>> OUTGOING IP addresses it uses to talk to the database server?
>> The database people want the requests to come FROM a different IP
>> address depending on the particular application.
>> I think it's impossible.
>> I told them to get another IP address for their database server and
>> then I can do it :-)
>> Anybody know if it's possible?
>> Eric
> A quick Google suggests that PHP always uses the IP that has the
> shortest path to the destination when sending packets, so you are
> going to have to do something "outside the box".
> A few things come to mind, in order of preference based on my
> impression of load:
>      1) There might be some things you could do with cgroups and/or
> Linux Containers (LXC) to mask out the IP addresses from the apps so
> that the only ones available are the ones you would like them to use,
>      2) iptables and NAT can be of use, as Doug suggests,
>      3) run a local reverse proxy (or even something like ncat), bound
> to localhost on a port for each app, and then have it establish the
> connections using the correct IPs for sources.
>      --Matt
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#  Eric Lucas
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