File Transfer Protocol (Chinese version) (iii)

5.4. Command and response sequence

Communication between the server and the user is a dialogue process. The user sends an FTP command, waits for one or more responses from the server, and then sends a new command based on the response.

Connection
The response contains a lot of information. Normally, the server returns a 220 response and waits for the input. After receiving the response, the user sends a new command. If the server cannot receive the input immediately, after 220
Returns the value 120. For example, if the server stops working after 15 minutes, the server sends messages to the user, but the server cannot send messages directly to the user. The message is buffered and returned in the next response.
Return to the user. The following lists the command responses. The first is the prepared response, the second is the final response, the third is the rejected response, and the third is the intermediate response. These responses form the basis of the status chart, which will be shown in the following section.
Given:

•  

  • Establish a connection

120

220

220

421

•  

  • Login

1. User

230

530

500,501,421

331,332

2. Pass

230

202

530

500,501,503,421

332

3. Acct

230

202

530

500,501,503,421

4. CWD

250

500,501,502,421,530,550

5. Cdup

200

500,501,502,421,530,550

6. SMNT

202,250

500,501,502,421,530,550

•  

  • Log out

1. Rein

120

220

220

421

500,502

2. Quit

221

500

•  

  • Transmission Parameters

1. Port

200

500,501,421,530

2. PASV

227

500,501,502,421,530

3. Mode

200

500,501,504,421,530

4. Type

200

500,501,504,421,530

5. Stru

200

500,501,504,421,530

•  

  • File Operation commands

Allo

200

202

500,501,504,421,530

Rest

500,501,502,421,530

350

Stor

125,150

(110)

226,250

425,426,451,551,552

532,450,452,553

500,501,421,530