I got 2 domain names, www.domain1.com and www.domain2.com. They have the same external IP address 10.10.10.10.

My router can redirect an external IP address to a LAN address.

(10.10.10.10 to 192.168.0.1)

Now I want www.domain1.com redirecting to 192.168.0.2, www.domain2.com redirecting to 192.168.0.3

I don't know if any software can do that for me. If there is, please let me know.

Thanks.

It sounds like you are talking about Network address translation. If you are trying to direct traffic at one address but designate it for two servers running the same application you would need a load balancer (like F5). If you are running differentiated services on different ports you need to do port address translation instead, that way your external address stays the same but you port traffic can go two different directions (i.e. port 80 traffic goes to 192.168.0.2 and port 445 to 192.168.0.3)

blah

look up some stuff on DNS...

What router are you using? A lot of SOHO class routers only allow for a single translation, but larger routers will allow multiple. Let me know and I can work up a sample config.