NAME
tftp —
trivial file transfer
program
SYNOPSIS
DESCRIPTION
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.
COMMANDS
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.
HISTORY
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.
SECURITY CONSIDERATIONS
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.