tftp
—
trivial file transfer program
tftp
is the user interface to the Internet TFTP (Trivial
File Transfer Protocol), which allows users to transfer files to and from a
remote machine. The remote host (and optional
port) may be specified on the command line, in which
case tftp
uses host (and
port) as the default for future transfers (see the
connect
command below).
The optional -e
argument sets a binary
transfer mode as well as setting the extended options as if
tout
, tsize
, and
blksize 65464
, had been given.
The Multicast TFTP option is supported in open-loop (i.e.,
"slave-only") mode based on IETF
draft-dion-tftp-multicast-option-01.txt (May 2002), which in turn was based
on RFC2026.
Once tftp
is running, it issues the prompt
‘tftp>
’ and recognizes the following
commands:
?
command-name ...
- Print help information.
ascii
- Shorthand for "mode ascii"
binary
- Shorthand for "mode binary"
blksize
blk-size
- Set the tftp blksize option to blk-size octets
(8-bit bytes). Since the number of blocks in a tftp
get
or put
is 65535, the
default block size of 512 bytes only allows a maximum of just under 32
megabytes to be transferred. The value given for
blk-size must be between 8 and 65464, inclusive.
Note that many servers will not respect this option.
connect
host-name [port]
- Set the host (and optionally
port) for transfers. Note that the TFTP protocol,
unlike the FTP protocol, does not maintain connections between transfers;
thus, the
connect
command does not actually create
a connection, but merely remembers what host is to be used for transfers.
You do not have to use the connect
command; the
remote host can be specified as part of the get
or
put
commands.
get
filename
-
get
remotename localname
-
get
file1 file2 ... fileN
- Get a file or set of files from the specified
sources. Source can be in one
of two forms: a filename on the remote host, if the host has already been
specified, or a string of the form hosts:filename to
specify both a host and filename at the same time. If the latter form is
used, the last hostname specified becomes the default for future
transfers.
mode
transfer-mode
- Set the mode for transfers; transfer-mode may be one
of ascii or binary. The default is
ascii.
put
file
-
put
localfile remotefile
-
put
file1 file2 ... fileN remote-directory
- Put a file or set of files to the specified remote file or directory. The
destination can be in one of two forms: a filename on the remote host, if
the host has already been specified, or a string of the form
hosts:filename to specify both a host and filename
at the same time. If the latter form is used, the hostname specified
becomes the default for future transfers. If the remote-directory form is
used, the remote host is assumed to be a UNIX
machine. If you need to specify IPv6 numeric address to
hosts, wrap them using square bracket like
[hosts]:filename to disambiguate the colon.
quit
- Exit
tftp
. An end of file also exits.
rexmt
retransmission-timeout
- Set the per-packet retransmission timeout, in seconds.
status
- Show current status.
timeout
total-transmission-timeout
- Set the total transmission timeout, in seconds.
tout
- Toggle the tftp "timeout" option. If enabled, the client will
pass its retransmission-timeout to the server. Note
that many servers will not respect this option.
trace
- Toggle packet tracing.
tsize
- Toggle the tftp "tsize" option. If enabled, the client will pass
and request the filesize of a file at the beginning of a file transfer.
Note that many servers will not respect this option.
verbose
- Toggle verbose mode.
The tftp
command appeared in
4.3BSD. IPv6 support was implemented by WIDE/KAME
project in 1999. TFTP options were implemented by Wasabi Systems, Inc., in
2003, and first appeared in NetBSD 2.0. Multicast TFTP
was implemented by Jared D. McNeill in 2006, and first
appeared in NetBSD 4.0.
Because there is no user-login or validation within the TFTP protocol, the
remote site will probably have some sort of file-access restrictions in place.
The exact methods are specific to each site and therefore difficult to
document here.