server.write()

// telnet defaults to port
EthernetServer server = EthernetServer(int);

server.write(val)
server.write(buf, len)

#include <Ethernet.h>
 
// network configuration.  gateway and subnet are optional.
 
byte mac[] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };  
//the IP address:
byte ip[] = { 10, 0, 0, 177 };    
// the router's gateway address:
byte gateway[] = { 10, 0, 0, 1 };
// the subnet:
byte subnet[] = { 255, 255, 0, 0 };
 
// telnet defaults to port 23
EthernetServer server = EthernetServer(23);
 
void setup()
{
  // initialize the ethernet device
  Ethernet.begin(mac, ip, gateway, subnet);
 
  // start listening for clients
  server.begin();
}
 
void loop()
{
  // if an incoming client connects, there will be bytes available to read:
  EthernetClient client = server.available();
  if (client == true) {
    // read bytes from the incoming client and write them back
    // to any clients connected to the server:
    server.write(client.read());
  }
}