[stunnel-users] client with two source IPs and one destination

Peter Pentchev roam at ringlet.net
Mon May 11 20:59:19 CEST 2020

On Mon, May 11, 2020 at 02:55:35PM -0400, Christopher Schultz wrote:
> Daniele,
> On 5/11/20 10:53, Daniele Basaldella wrote:
> > Dear group,
> > I've to configure a couple of tunneled connections (call them TC1 and
> > TC2), client side, on a linux system.
> > The target of both such connections is the same (destination ip and port
> > are the same, call it DST).
> > At source side (my server) I have a two IP addresses (call them IP1 and
> > IP2) assigned and currently working to its unique NIC. I normally use
> > iptables SNAT to split the traffic between IP1 and IP2 depending on
> > destination addresses but in this case I've to distinguish it at
> > application level (TC1 and TC2).
> > I'd like to get TC1 to set the outgoing traffic with source address IP1
> > and TC2 to set outgoing traffic with source address IP2. 
> > 
> >     Tunnel           Tunnel
> >     Client           Server
> > 
> > TC1:  IP1    --\
> >                 >-->   DST 
> > TC2:  IP2    --/
> > 
> > I'm thinking to set one entry in stunnel.conf for each TC1 and TC2 and
> > use *transparent* = source  clause to set the source address but it
> > seems my case is not so common and I didn't find documentation. 
> > Please could you suggest a solution.
> If it's important for you to set the outgoing interface, then you should
> use:
> local=IP1
> in your config for the tunnel definition.

I believe Daniele's main point was the desire to avoid having two
sections in the stunnel config, one with accept=IP1 and local=IP1
and one with IP2. Whether it can be done with transparent proxying is
something I've never tried, so I don't feel qualified to answer.


Peter Pentchev  roam at ringlet.net roam at debian.org pp at storpool.com
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