authentication

校园网拨号端软件

struct drcom_auth

For every UDP packet and every TCP connection, with the other end outside the
ISP network, we add authentication data.

For UDP, the packet is prepended with this 16 byte data.

For TCP, the first outgoing packet of every connection is preceded with this
16 byte data.

struct drcom_auth
{
  char drco[4];
  u_int32_t servip;
  u_int16_t servport;
  u_int32_t hostip;
  u_int16_t hostport;
}  __attribute__ ((__packed__));

drco is "Drco".

the names servip, servport, hostip, hostport are just my inventions.