Change TCP and UDP IP address

What I want to do is address translation for all public IPs and turns them to private IPs.

 

I want to trick a router that has a default route 0.0.0.0 to 172.16.20.10. This router sends all unknown traffic to Internet by the router with the 172.16.20.10 IP, but I need that in sometimes it sends all traffic to another router 172.16.20.20. I mean, I need that default route but in some times I do not (what I am trying to do is like a dynamic default route).

 

 

I need when all the traffic goes through the LTM an irule changes the public IP to a private one, let’s say 200.11.22.33 to 10.10.10.2, then all traffic goes through the first router. When the packets arrives at the second LTM, another irule changes the private one to a public ip again (the original) 10.10.10.2 to 200.11.22.33

 

 

I will hide the public IP into the payload at this way:

 

 

Set XX [scan [IP:: remote_addr] " %d.%d.%d.%d"]

 

Set yy [binary format c4 $xx]

 

TCP:: payload replace 0 0 $yy

 

here I need to change any public IP by a private (65.33.44.55 to 10.10.10.2) or (200.10.20.30 to 10.10.10.2) or any public IP to 10.10.10.2

 

 

Then in the second LTM (irule 2) I am going to look for the original IP an put it back again

 

 

Set zz [binary scan [TCP:: payload] a4 XX]

 

here I need to put the public IP again (the original)

 

 

can it be performed with the node command?