Dear All ,
I am facing a trouble in setting SNAT through my virtual interface .
I have 2 LAN cards , one is internal and another is external ,On external I have mentioned 1 virtual ip, but somehow , I am only able to DNAT it no SNAT o virtual ip . Also I am able to do SNATING through my external ip .
But this donot solve my purpose.

Scenario
Internal interface ip = A.A.A.A
Private ip to be Natted = E.E.E.E
External interface ip = B.B.B.B
Virtual ip on External interface = D.D.D.D

I want to do 1:1 nating between E.E.E.E and D.D.D.D
These are the rules which are not working

-A PREROUTING -d D.D.D.D -j DNAT --to-destination E.E.E.E ----->OK
-A POSTROUTING -s E.E.E.E -j SNAT --to-source D.D.D.D ------>Not working

Kindly suggest some way

seems like it should work, at least the iptables rules look good.

how have you configured your 'virtual ip'? I take it you mean that you just have two IP addrs configured on the outside interface, one on eth0 and one on eth0:0 (or similar), the eth0:0 being the vip you're talking about?

what distro are you using, and what kernel version?