FreeTDS Development Group

[Marten Lehmann <lehmann AT cnm.de>]

Hello,

I'm not much into the glibc socket API, but the perl module 
http://search.cpan.org/~gbarr/IO-1.25/lib/IO/Socket/INET.pm manages to 
exactly do this: Define the local IP (and even port) a connection is 
made from.

First it looks if the option LocalAddr is specified, otherwise it leaves 
the decision to the OS:

$laddr = defined $laddr ? inet_aton($laddr) : INADDR_ANY;

And then, before connect() is called, it binds to the interface:

if($lport || ($laddr ne INADDR_ANY) || exists $arg->{Listen}) {
    $sock->bind($lport || 0, $laddr) or
        return _error($sock, $!, "$!");
}

If someone knows the underlying socket API of the OS, he can surely 
adapt this to create a localaddr option or similar for FreeTDS.

Kind regards
Marten Lehmann

On 18.10.2012 07:36, James K. Lowden wrote:
> On Thu, 18 Oct 2012 04:18:00 +0200
> Marten Lehmann <lehmann AT cnm.de> wrote:
>
> > How can I set the local ip address / interface that FreeTDS connects
> > from to the remote database host?
>
> There is no facility in FreeTDS to control which interface is used.  I
> cannot offhand think of any way to control that using the standard
> socket interface i.e. connect(2).   That sort of thing would be
> governed by the routing tables within the machine hosting the FreeTDS
> application.
>
> If I may ask, what prompts you to introduce a firewall between your
> webserver and your database server?  Surely the database server is on
> a network not accessible from the outside?
>
> --jkl
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