1. ( Post Office Protocol - Version 3 ) POP3 RFC 1939 報告學生 : 駱正哲

2. POP3 smtp server User Agent mail drop POP3 Server TCP port 110 smtp port

3. POP3 +OK -ERR command arguments CRLF case-insensitive (status indicator) responses CRLF responses CRLF 40 characters 512 characters message format responses CRLF. CRLF

4. POP3 AUTHORIZATION TRANSACTION UPDATE USER / PASS APOP POP3 AUTH QUIT LIST,RETR, DELE …… QUIT Three stages greeting

5. POP3 AUTHORIZATION STAGE USER / PASS Plaintext USER nameresponse : +OK Password required for name. PASS stringresponse : +OK name has n messages (m octets). space acceptable dangerous

6. POP3 AUTHORIZATION STAGE APOP 1. A timestamp in greeting 2. APOP user digestdigest Timestamp ex. 16 octets Hexadecimal ( and lower-case ASCII)

7. POP3 AUTHORIZATION STAGE MD 5 timestampshared secret digest

8. POP3 AUTHORIZATION STAGE POP3 AUTH +OK maildrop locked and ready -ERR authentication exchange failed AUTH mechanism : server challenge : + ( BASE64 encoded string) client answer : ( BASE64 encoded string) client cancel : *

9. Exclusive-access lock on the maildrop POP3 AUTHORIZATION STAGE Mailbox Pop3 client new mail Mailbox new mail

10. POP3 TRANSACTION STAGE STAT:issue a drop listing for that maildrop response :+OK nn mm number of messages total size in octet (decimal) STAT +OK 10 7817

11. POP3 TRANSACTION STAGE LIST (msg) :List messages in the mailfrop or issue a scan listing for that message LIST +OK 10 messages (7817 octets) 1 528 2 852 3 852 4 852 5 852 6 852 7 852 8 852 9 661 10 664. LIST 9 +OK 9 661

12. POP3 TRANSACTION STAGE RETR msg :+OK (message body) -ERR no such message DELE msg :+OK message deleted -ERR no such message NOOP :+OK

13. POP3 TRANSACTION STAGE UIDL (msg) :+OK unique-id listing -ERR no such message 1 ～ 70 characters Between : 0x21 ～ 0x7E unique - idmessage HASH

14. POP3 TRANSACTION STAGE UIDL +OK uidl command accepted. 1 e73f7d065d8ca4c4388ee3123c2b855a 2 1493e2eff10ccce447c30c3a3f78b610 3 a9df87f9ca8ccbf72cb095c2ba643027 4 ed16b3f3f00b53d0a7553eec96082efc 5 0a537b201c8859977a133ee771f5f45b 6 8451993202d8cc7da7d713548b5ea174 7 32653368f747914f6e48c98692c38bf9 8 fab3686e92be670ebe5e2514563cc44b 9 076ac86d0efeea6bca94240b4282f119 10 5b3beb2d4c42f3563c19135b0ec0ff29.

15. POP3 UPDATE STAGE Remove message marked deleted Close TCP connection