( Post Office Protocol - Version 3 ) POP3 RFC 1939 報告學生 : 駱正哲
POP3 smtp server User Agent mail drop POP3 Server TCP port 110 smtp port
POP3 +OK -ERR command arguments CRLF case-insensitive (status indicator) responses CRLF responses CRLF 40 characters 512 characters message format responses CRLF. CRLF
POP3 AUTHORIZATION TRANSACTION UPDATE USER / PASS APOP POP3 AUTH QUIT LIST,RETR, DELE …… QUIT Three stages greeting
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
POP3 AUTHORIZATION STAGE APOP 1. A timestamp in greeting 2. APOP user digestdigest Timestamp ex. 16 octets Hexadecimal ( and lower-case ASCII)
POP3 AUTHORIZATION STAGE MD 5 timestampshared secret digest
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 : *
Exclusive-access lock on the maildrop POP3 AUTHORIZATION STAGE Mailbox Pop3 client new mail Mailbox new mail
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
POP3 TRANSACTION STAGE LIST (msg) :List messages in the mailfrop or issue a scan listing for that message LIST +OK 10 messages (7817 octets) LIST 9 +OK 9 661
POP3 TRANSACTION STAGE RETR msg :+OK (message body) -ERR no such message DELE msg :+OK message deleted -ERR no such message NOOP :+OK
POP3 TRANSACTION STAGE UIDL (msg) :+OK unique-id listing -ERR no such message 1 ~ 70 characters Between : 0x21 ~ 0x7E unique - idmessage HASH
POP3 TRANSACTION STAGE UIDL +OK uidl command accepted. 1 e73f7d065d8ca4c4388ee3123c2b855a e2eff10ccce447c30c3a3f78b610 3 a9df87f9ca8ccbf72cb095c2ba ed16b3f3f00b53d0a7553eec96082efc 5 0a537b201c a133ee771f5f45b d8cc7da7d713548b5ea f747914f6e48c98692c38bf9 8 fab3686e92be670ebe5e cc44b 9 076ac86d0efeea6bca94240b4282f b3beb2d4c42f3563c19135b0ec0ff29.
POP3 UPDATE STAGE Remove message marked deleted Close TCP connection