| Reply Code | Typical Reply Text | Description |
|---|---|---|
| 110 | Restart marker reply. | Used as part of the marker restart feature when transferring in block mode. |
| 120 | Service ready in nnn minutes. | nnn indicates the number of minutes until the service will be available. |
| 125 | Data connection already open; transfer starting. | |
| 150 | File status okay; about to open data connection. | |
| 200 | Command okay. | Sometimes the text indicates the name of the command that was successful. |
| 202 | Command not implemented, or superfluous at this site. | |
| 211 | System status, or system help reply. | Will contain system-specific status or help information. |
| 212 | Directory status. | |
| 213 | File status. | |
| 214 | Help message. | Includes help information of use to a human user of this server. |
| 215 | NAME system type. | NAME is the name of a type of operating system. Often sent as a reply to the SYST command. |
| 220 | Service ready for new user. | Sent when the command channel is established before the USER command is sent. |
| 221 | Service closing control connection. | A goodbye message sent when the session is closed. |
| 225 | Data connection open; no transfer in progress. | |
| 226 | Closing data connection. | Sent after a successful file transfer or a file abort. |
| 227 | Entering Passive Mode (h1,h2,h3,h4,p1,p2). | Sent in reply to the PASV command, indicates the IP address and port to use for the data connection. |
| 230 | User logged in, proceed. | Sent after successful USER and PASS authentication. Systems often include additional greeting or other information with this code after a login. |
| 250 | Requested file action okay, completed. | The text description will provide more details about what was successfully done, such as confirming a change of directory or deleted file. |
| 257 | "PATHNAME" created. | "PATHNAME" is replaced by the path created. |
| 331 | User name okay, need password. | Intermediate result after sending USER but before sending PASS. |
| 332 | Need account for login. | |
| 350 | Requested file action pending further information. | |
| 421 | Service not available, closing control connection. | Sometimes sent if the FTP server is in the process of shutting down. |
| 425 | Can't open data connection. | |
| 426 | Connection closed; transfer aborted. | |
| 450 | Requested file action not taken. File unavailable. | The file is not available; for example, it may be locked by another user. Contrast to reply code 550. |
| 451 | Requested action aborted: local error in processing. | |
| 452 | Requested action not taken. Insufficient storage space in system. | The file system is full. |
| 500 | Syntax error, command unrecognized. | Bad or excessively long command line was sent. |
| 501 | Syntax error in parameters or arguments. | |
| 502 | Command not implemented. | |
| 503 | Bad sequence of commands. | |
| 504 | Command not implemented for that parameter. | |
| 530 | Not logged in. | Sent if authentication fails due to a bad user name or incorrect password. |
| 532 | Need account for storing files. | |
| 550 | Requested action not taken. File unavailable. | File was not found or user does not have access to it. This error code may be sent in reply to any file transfer command if the user has not successfully logged in yet. Contrast to reply code 450. |
| 551 | Requested action aborted: page type unknown. | |
| 552 | Requested file action aborted. Exceeded storage allocation. | |
| 553 | Requested action not taken. File name not allowed. | |
| 10065 | No route to host |
| number | When used as 1st digit | When used as 2nd digit |
|---|---|---|
| 0 | (not used) | Syntax These replies refer to syntax errors, syntactically correct commands that don't fit any functional category, unimplemented or superfluous commands. |
| 1 | Positive Preliminary reply The requested action is being initiated; expect another reply before proceeding with a new command. (The user-process sending another command before the completion reply would be in violation of protocol; but server-FTPprocesses should queue any commands that arrive while a preceding command is in progress.) This type of reply can be used to indicate that the command was accepted and the user-process may now pay attention to the data connections,for implementations where simultaneous monitoring is difficult. |
Information - These are replies to requests for information, such as status or help. |
| 2 | Positive Completion reply The requested action has been successfully completed. A new request may be initiated. |
Connections Replies referring to the TELNET and data connections. |
| 3 | Positive Intermediate reply The command has been accepted, but the requested action is being held in abeyance, pending receipt of further information. The user should send another command specifying this information. This reply is used in command sequence groups. |
Authentication and accounting Replies for the logon process and accounting procedures. |
| 4 | Transient Negative Completion reply The command was not accepted and the requested action did not take place, but the error condition is temporary and the action may be requested again. The user should return to the beginning of the command sequence, if any. It is difficult to assign a meaning to "transient", particularly when two distinct sites (Server and User-processes) have to agree on the interpretation. Each reply in the 4yz category might have a slightly different time value, but the intent is that the user-process is encouraged to try again. A rule of thumb in determining if a reply fits into the 4yz or the 5yz (Permanent Negative) category is that replies are 4yz if the commands can be repeated without any change in command form or in properties of the User or Server (e.g. the command is spelled the same with the same arguments used; the user does not change his file access or user name; the server does not put up a new implementation.) |
(not used) |
| 5 | Permanent Negative Completion reply The command was not accepted and the requested action did not take place. The User-process is discouraged from repeating the exact request (in the same sequence). Even some "permanent" error conditions can be corrected, so the human user may want to direct his User-process to reinitiate the command sequence by direct action at some point in the future (e.g. after the spelling has been changed, or the user has altered his directory status.) |
File system These replies indicate the status of the Server file system vis-a-vis the requested transfer or other file system action. |
| 6 to 9 | (not used) | |
FTP is a protocol designed to transfer files over TCP-based networks (LAN, WAN).
FTP uses separate control and data connections between the client and the server. FTP normally transfers data by having the server connect back to the client, after the PORT command is sent by the client. This is problematic when it comes to firewalls and NAT.
Hey server, I'm opening this port, please connect to it for data connection. This would be done with :
PORT a,b,c,d,4,1
Hey server, I want to open a data connection to you, which port should I connect to?, to what the server may answer :
227 Entering Passive Mode (192,168,0,100,105,163)
