sending additional client info to server in C# -

i have written client program using c# socket programming send file server. there way can send client id (say: 1234) server server can recognize different clients? modification have make in following code?

// client    using system; using system.collections.generic; using system.net; using system.net.sockets; using system.io; using system.text;  namespace filetransferclient { class program {     static void main(string[] args)     {         try         {                          string filename = @"d:\demo.txt";             string p = path.getextension(filename);             fileinfo f = new fileinfo(filename);             long s1 = f.length;              tcpclient tcpclient = new tcpclient("127.0.0.1", 1234);             console.writeline("connected. sending file.");              streamwriter swriter = new streamwriter(tcpclient.getstream());              byte[] bytes = file.readallbytes(filename);              swriter.writeline(bytes.length.tostring());             swriter.flush();              swriter.writeline(filename);             swriter.flush();              console.writeline("sending file");             tcpclient.client.sendfile(filename);          }         catch (exception e)         {             console.write(e.message);         }          console.read();     } } }