Hello everyone. I'm sorry that my english is poor. If u can't understand me , I'll tell u more details.
First, I describe the structure of that special network here
There're many computers in the LAN, assigned an unique IP address through DHCP Server, but they can't access each other even if specific ports are opened. I CAN find workgroups and there computers with hostnames by "My Network Place" in MS
Windows(i'm using 2003 ent). When I want to open the tag of the property of each computers. I got an error message said that:"The computer can't be found!". I used a scaning tool and got all the IP addresses that are activite in LAN ,but there MAC is the same as the GATEWAY.
Someone told me that :because I can see the hostnames, maybe I can access them by communication based on UDP. I wrote two programs, a server and a client based on UDP by C#.
But I failed to communicate the other PCs.
Who can tell me that how can i write program to make communication available!. Thank u very much
How to access this special network 
Linear Mode
