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ProFTPD: Supported FTP Commands
ProFTPD: Supported FTP Commands
Supported FTP Commands
ABOR
ALLO
Short for ALLOcate.
APPE
Short for APPEnd.
AUTH
Short for AUTHenticate (supported by mod_tls)
CDUP
Short for Change Directory UP, this command is used
to move the client's "location" on the server up one level in
the filesystem hierarchy.
CLNT
Short for CLieNT, this command is used by clients to
offer/provide any freeform identification they desire to the server.
CWD
Short for Change Working Directory.
DELE
Short for DELEte, this command is used by the client to tell the
server to delete a file.
EPRT
Short for Extended PoRT, an enhanced version of
the PORT command that can handle IPv6
addresses.
EPSV
Short for Extended PaSsiVe, an enhanced
version of the PASV command that can
handle IPv6 addresses.
FEAT
Short for FEATures, this command is used by the client to request
a descriptive list of server-supported features.
HASH
This command is used by clients to request the checksum, or "hash", of
a file on the server. This command is available when the
mod_digest module
is compiled/loaded.
HELP
HOST
This command is the equivalent of HTTP's "Host" header for FTP, providing
the ability to have name-based virtual hosting.
LANG
LIST
MDTM
Short for MoDification TiMe, this command
is used by the client to request the modification time of a file on the
server. This command is defined formally in RFC 3659, and is a commonly implemented FTP command.
Note that this command cannot be used to change the
modification time of the file on the server; it only reports on the
file's modification time. The MFMT
command is used to change a file's modification time.
MFMT
Short for Modify Fact: Last Modified Time,
supported by mod_facts.
Some clients use this command to change the last modified timestamp on
a newly uploaded file so that the timestamp on the server matches the
timestamp of that file on the client.
MKD
Short for MaKe Directory.
MLSD
Short for Machine LiSting, Directory, supported
by mod_facts. Unlike
the LIST command, whose response format
was never specified, the MLSD command has a strictly defined
response format (see RFC 3659 for details). This format was designed to be easily machine parseable,
for automated processing of directory listing formats; the format was also
designed to be platform-agnostic, and thus portable.
MLST
Short for Machine LiSTing, supported by
mod_facts. This
command is similar to MLSD in that it
uses the same response format. Unlike MLSD, the response for a
MLST is sent back on the control connection rather than
using a data connection, and is for a single file only.
MODE
There are three mode types defined by RFC 959; proftpd only supports one (i.e. Stream).
NLST
Short for Name LiST.
NOOP
Short for NO OPeration. This command has no functionality, and
is often used as a session keepalive mechanism.
OPTS
Short for OPTionS. This command is used to specify
optional parameters for the command to follow the OPTS
command, if that command supports such optional parameters.
PASS
Short for PASSword, the client uses this command to convey the
password of the user attempting to log into the server.
PASV
Short for PASsiVe, the client uses this command to ask the
server for a port to which the client should connect, indicating a
passive data transfer.
PBSZ
Short for Protection Buffer SiZe. Used
to determine the size of a buffer needed for secure handshaking (supported
by mod_tls)
PORT
The client uses this command to tell the server to what client-side port
the server should contact; use of this command indicates an active data
transfer.
PROT
Short for PROTection. Used to set the protection level on the
data channel (supported by
mod_tls)
PWD
Short for Print Working Directory.
QUIT
RANG
Short for RANGe, this command is used by clients to request
that a specific range of bytes be transferred for files, including
uploads and downloads; supported by
mod_xfer and defined by
this IETF
Draft.
REST
Short for RESTart, this command is used by the client to tell the
server that it would like to restart a previous data transfer, either
upload or download.
RETR
Short for RETRieve, this command is used by the client to inform
the server of the file the client would like to download. On many FTP
client, this is implemented using the client-specfic "get"
command.
RMD
Short for ReMove Directory, this command is used
to have the server delete the requested directory from its filesystem.
RNFR
Short for ReName FRom.
RNTO
Short for ReName TO.
SITE
This command is used for site-specific commands. See below for descriptions
of proftpd's SITE commands.
SIZE
SSCN
Short for Set Secured Client Negotiation, this
non-standard command is used by FTPS clients to tell a server to use TLS
when performing a site-to-site transfer. For more details, see
here.
STAT
STOR
Short for STORe, this command is used by the client to tell the
the server that the client will be uploading data for a file to stored
on the server using the filename given. On many FTP clients, this
is implemented using the client-specific "put" command.
STOU
Short for STOre Uunique, it requests that the file being
stored on the server be given a unique filename. The server chooses the
unique name for the stored file, and reports the name chosen back to
the client. On some FTP clients, this ability is enabled using the
client-specific "sunique" command.
SYST
TYPE
USER
An FTP client uses this command to inform the server of the name of the
user requesting an FTP session.
XCUP
This is an X-variant of the CDUP command,
and has the same functionality.
XCWD
This is an X-variant of the CWD command,
and has the same functionality.
XMKD
This is an X-variant of the MKD command,
and has the same functionality.
XPWD
This is an X-variant of the PWD command,
and has the same functionality.
XRMD
This is an X-variant of the RMD command,
and has the same functionality.
Supported SITE commands
CHGRP
Short for CHange GRouP.
Example:
SITE CHGRP ftpgroup script.cgi
CHMOD
Short for CHange MODe.
Example:
SITE CHMOD 755 script.cgi
HELP
MKDIR
Similar to the MKD command, this
SITE can be used to create a directory. It will, unlike
MKD, also create any directories in the path that do
not exist.
Example:
SITE MKDIR /path/to/some/dir/that/is/not/there/
Supported by the mod_site_misc module.
RMDIR
Similar to the RMD command, this
SITE can be used to remove a directory. It will, unlike
RMD, also delete any files in the directory.
Example:
SITE RMDIR /path/to/some/dir/with/files/
Supported by the mod_site_misc module.
SYMLINK
Used to create a symbolic link (a.k.a. a symlink) from
the source path (src) to the destination path (dest).
Example:
SITE SYMLINK src dest
Supported by the mod_site_misc module.
UTIME
Used to update the access and modification timestamps on a file.
Example:
SITE UTIME 200412312359 /path/to/some/file.txt
Supported by the mod_site_misc module.
Unsupported FTP Commands
ACCT
Short for ACCounT
MACB
Short for MACintosh Binary. This command is not defined in
any RFC, and is something of a hack added by Apple in order to support
transfers of the resource forks of Mac files.
REIN
SMNT
STRU
Short for STRUcture. proftpd only supports a
STRU parameter of type F (for "file"),
and so does not support this command.
Frequently Asked Questions
Question: I can use the RNFR and
RNTO commands to move a file, even across different
disks/mount points. And I can use RNFR/RNTO to move
a directory, but I cannot move a directory across different
disks/mount points. Is this a bug?
Answer: No, it is not a bug. Why not? Ultimately,
it is because the FTP specifications do not guarantee (or even discuss)
that an FTP implementation must support renaming of directories across
mount points.
ProFTPD implements the RNFR/RNTO functionality
by using the rename(2) system call. And rename(2)
is documented to not work across mount points.
"But then why does it work when I rename a file across mount points?" you
ask. Good question. The answer is that for files only, ProFTPD
detects the rename(2) error for renaming across mount points,
and then copies the file in question to the new location, deleting
the old location when the copy completes successfully.
"Great!" you say, "Now do the same thing for directories!" Unfortunately, for
directories, the answer is not that simple. Here are some things to consider
when copying directories: what if the directory contains sockets, FIFOs,
devices, and other irregular file types which cannot be easily copied/moved?
Should copying/moving of directories automatically use root privileges in
order to preserve the ownership on files that do not belong to the logged-in
user? What if the copying/deleting of files fails in the midde: what should
then happen to the copied (and remaining) files/directories?
Since there are no easy answers as yet to the above questions, ProFTPD now
detects the rename(2) error for renaming across mount points
for a directory, and rejects the RNTO command, showing
something like:
RNFR directory
350 File or directory exists, ready for destination name
RNTO /other/mount/directory
550 Rename /other/mount/directory: Is a directory
That "Is a directory" error indicates that ProFTPD cannot rename a directory
across the mount points you requested. (That particular error message can,
and will, be made more informative.)
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