Re: Half--NAT

From: Jason J. W. Williams <>
Date: Thu, 24 Mar 2011 15:28:29 -0600

Hi David,

I'd argue HAProxy is more of a L4-7 load balancer than just a proxy, and that's what we're trying to use it as on L4.

The functionality I need to replace is Half-NAT in a hardware load balancer: Select a backend server according to the SLB algorithm and rewrite the destination address (keeping the source IP as the client IP) on the packet to the RIP of the server before sending it along. Enables the load balancer to do balancing and the server to still see the client's IP address. At L4 there's not really another way get the client IP visible to the server (we're SLBing SMTP).


On Thu, Mar 24, 2011 at 3:12 PM, David Birdsong <>wrote:

> I don't think you'll find NAT capabilities in any proxy. I think a
> fair distinction between a proxy and a NAT device is:
> - a proxy actually listens and will call accept to create a separate
> socket connection with both client and server
> - a NATing device doesn't know about sockets at all and will simply
> rewrite IP and sometimes TCP/UDP headers
> On Thu, Mar 24, 2011 at 4:59 PM, Jason J. W. Williams
> <> wrote:
> > Hi All,
> > I'm trying to find documentation on configuring HAProxy to do half-NAT,
> but
> > can't seem to find any. Does HAProxy not support half-NAT or does it call
> it
> > something else? Thank you in advance for your help.
> > -J
Received on 2011/03/24 22:28

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