Is there a way....

[David Sims <dpsims@dpsims.com>]

Hi,

  I want to use Linux to do NAT between some 192.168.x.x addresses
in a routed network on one side and a single 10.0.0.x/24 on the other
side. I want to do one-to-one NAT but in a dynamic way... such that a
calling address is NATed into the next available 10.0.0.x/24.... in a
round robin sort of way... IS there a way to do this using NETFILTER??
If not NETFILTER, then how??

  This sort of thing is common in many-to-one NAT (port-address
translation)... but I need each call to come from a separate NATed IP
address to support my application (TN3270 session)... It's OK to reuse
addresses after a call (session) is complete, but each session needs to
come from it's own fixed (for the duration of the session) IP address....

  The exact application that I am trying to support is connecting to an
IBM mainframe from random hosts in a routed network via an Attachmate
gateway where calling addresses are mapped into terminal sessions on a 1:1
basis.... Port address translation won't work because all calls appear to
eminate from the single IP address.... I need to do 1:1 NAT but only on a
temporary basis where once a call is complete the NAT address can be used
by another caller...

  Clues? Suggestions? Examples?

TIA,

Dave