Why the guest can't access host's virtual adapter?

Question

I installed vmware workstation with 1 guest OS(Ubuntu). My host system is windows. I use NAT as guest OS's network type. So, right now, the situation is:

1. In host system, there is a virtual adapter vmnet8, IP address is 192.168.142.1

2. In vmware network editor, the NAT configuration is: the gateway is 192.168.142.2(I don't know where this 192.168.142.2 comes from, this is the default value vmware workstation provided and it works -- guest system can access the Internet).

3. The guest system use DHCP and acquired an IP address 192.168.142.128

So, the problem is: Host system can access guest system(SSH, samba...) but the guest system can't access host system(E.g: in guest system, "ping 192.168.142.1" shows no reponse packet received).

I want guest system can access host system right now because I wrote a network program which runs in guest system and it will talk with another program runs in host system.

Thank you for any helps.