Hi,
I am using a virtual machine on my machine. My system ip address is 192.168.0.12, Gate way 192.168.0.1 mask is 255.255.255.0. My virtual machine's ip is 192.168.1.25. Now how do i do ssh to my virtual machijne. what gate way should i use on vartual host and what are the iptables rule should use on virtual machine. so that virtual machine should provide service to 192.168.0.0 network. Thanks for any help...

What virtualization application are you using? VMware Server, Xen, something else? The instructions are different for each.

If you're using VMware Server and you choose NAT for the network type, then the virtual guest (don't call it "host", in VMware-speak "host" is the machine that's running VMware, while "guests" are OSs running inside VMware) should set it's gateway to 192.168.1.2, assuming you have configured VMware to use this network for NAT (did you do that, or did you just pick an IP at random?). The guest should also set nameserver 192.168.1.2 in /etc/resolv.conf . You'll need to configure the nat.conf in VMware to use a local port in your host OS to forward to the guest OS for ssh.

I am using RHX_groundwork which is running under XEN Kernel.