passwd

这是一个关于linux下上外网的drcom1.4.4

After sending REQUEST and receiving CHALLENGE, we send
a password change request packet:

struct drcom_passwd_packet
{
  struct drcom_host_header host_header;
  char username[16];
  u_int8_t checksum1_xor[16];
  u_int32_t unknown0;
  u_int32_t unknown1;
  u_int32_t unknown2;
  u_int32_t unknown3;
} __attribute__ ((__packed__));

pkt_type is 09 01.

len is sizeof(struct drcom_passwd_packet).

checksum1_xor is MD5 checksum of:
- checksum0 of host_header
- old password (excluding null bytes)
concatenated together.
Then the checksum is xor'ed with the new password.

unknown0 is LSB 0x12.

unknown1 is LSB 0x16.

unknown2 is LSB 0x04.

unknown3 is 0.

The unknowns can be overwritten by the username (if it's long
enough) except unknown3 and the second half of unknown2.