xref: /freebsd/usr.bin/tftp/tftp.1 (revision bdcbfde31e8e9b343f113a1956384bdf30d1ed62)

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.Dd March 2, 2020
.Dt TFTP 1
.Os
.Sh NAME
.Nm tftp
.Nd trivial file transfer program
.Sh SYNOPSIS
.Nm
.Op Ar host Op Ar port
.Sh DESCRIPTION
The
.Nm
utility is the user interface to the Internet
.Tn TFTP
(Trivial File Transfer Protocol),
which allows users to transfer files to and from a remote machine.
The remote
.Ar host
may be specified on the command line, in which case
.Nm
uses
.Ar host
as the default host for future transfers (see the
.Cm connect
command below).
.Sh COMMANDS
Once
.Nm
is running, it issues the prompt
.Dq Li tftp>
and recognizes the following commands:
.Pp
.Bl -tag -width verbose -compact
.It Cm \&? Ar command-name ...
Print help information.
.Pp
.It Cm ascii
Shorthand for "mode ascii"
.Pp
.It Cm binary
Shorthand for "mode binary"
.Pp
.It Cm blocksize Ar [size]
Sets the TFTP blksize option in TFTP Read Request or Write Request packets
to
.Ar [size]
as specified in RFC 2348.
Valid values are between 8 and 65464.
If no blocksize is specified, then by default a blocksize of 512 bytes
will be used.
.Pp
.It Cm blocksize2 Ar [size]
Sets the TFTP blksize2 option in TFTP Read Request or Write Request packets
to
.Ar [size] .
Values are restricted to powers of 2 between 8 and 32768.
This is a non-standard TFTP option.
.Pp
.It Cm connect Ar host Op Ar port
Set the
.Ar host
(and optionally
.Ar port )
for transfers.
Note that the
.Tn TFTP
protocol, unlike the
.Tn FTP
protocol,
does not maintain connections between transfers; thus, the
.Cm 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
.Cm connect
command; the remote host can be specified as part of the
.Cm get
or
.Cm put
commands.
.Pp
.It Cm debug Ar level
Enable or disable debugging levels during verbose output.
The value of
.Ar level
can be one of
.Cm packet , simple , options ,
or
.Cm access .
.Pp
.It Cm get Oo Ar host : Oc Ns Ar file Op Ar localname
.It Cm get Xo
.Oo Ar host1 : Oc Ns Ar file1
.Oo Ar host2 : Oc Ns Ar file2 ...
.Oo Ar hostN : Oc Ns Ar fileN
.Xc
Get one or more files from the remote host.
When using the
.Ar host
argument, the
.Ar host
will be used as default host for future transfers.
If
.Ar localname
is specified, the file is stored locally as
.Ar localname ,
otherwise the original filename is used.
Note that it is not possible to download two files at a time, only
one, three, or more than three files, at a time.
.Pp
To specify an IPv6 numeric address for a host, wrap it using square
brackets like
.Dq Li [3ffe:2900:e00c:ffee::1234] : Ns Ar file
to disambiguate the
colons used in the IPv6 address from the colon separating the host and
the filename.
.Pp
.It Cm mode Ar transfer-mode
Set the mode for transfers;
.Ar transfer-mode
may be one of
.Em ascii
or
.Em binary .
The default is
.Em binary .
.Pp
.It Cm packetdrop [arg]
Randomly drop
.Ar arg
out of 100 packets during a transfer.
This is a debugging feature.
.Pp
.It Cm put Ar file Op Oo Ar host : Oc Ns Ar remotename
.It Cm put Ar file1 file2 ... fileN Op Oo Ar host : Oc Ns Ar remote-directory
Put a file or set of files to the remote host.
When
.Ar remotename
is specified, the file is stored remotely as
.Ar remotename ,
otherwise the original filename is used.
If the
.Ar remote-directory
argument is used, the remote host is assumed to be a
.Ux
machine.
To specify an IPv6 numeric address for a
.Ar host ,
see the example under the
.Cm get
command.
.Pp
.It Cm options Ar [arg]
Enable or disable support for TFTP options.
The valid values of
.Ar arg
are
.Cm on
(enable RFC 2347 options),
.Cm off
(disable RFC 2347 options), and
.Cm extra
(toggle support for non-RFC defined options).
.Pp
.It Cm quit
Exit
.Nm .
An end of file also exits.
.Pp
.It Cm rexmt Ar retransmission-timeout
Set the per-packet retransmission timeout, in seconds.
.Pp
.It Cm rollover [arg]
Specify the rollover option in TFTP Read Request or Write
Request packets.
After 65535 packets have been transmitted, set the block counter to
.Ar arg .
Valid values of
.Ar arg
are 0 and 1.  This is a non-standard TFTP option.
.Pp
.It Cm status
Show current status.
.Pp
.It Cm timeout Ar total-transmission-timeout
Set the total transmission timeout, in seconds.
.Pp
.It Cm trace
Toggle packet tracing.
.Pp
.It Cm verbose
Toggle verbose mode.
.Pp
.It Cm windowsize Op Ar size
Sets the TFTP windowsize option in TFTP Read Request or Write Request packets to
.Op Ar size
blocks as specified in RFC 7440.
Valid values are between 1 and 65535.
If no windowsize is specified,
then the default windowsize of 1 block will be used.
.El
.Sh SEE ALSO
.Xr tftpd 8
.Pp
The following RFC's are supported:
.Rs
.%T RFC 1350: The TFTP Protocol (Revision 2)
.Re
.Rs
.%T RFC 2347: TFTP Option Extension
.Re
.Rs
.%T RFC 2348: TFTP Blocksize Option
.Re
.Rs
.%T RFC 2349: TFTP Timeout Interval and Transfer Size Options
.Re
.Rs
.%T RFC 3617: Uniform Resource Identifier (URI) Scheme and Applicability Statement for the Trivial File Transfer Protocol (TFTP)
.Re
.Rs
.%T RFC 7440: TFTP Windowsize Option
.Re
.Pp
The non-standard
.Cm rollover
and
.Cm blksize2
TFTP options are mentioned here:
.Rs
.%T Extending TFTP
.%U https://www.compuphase.com/tftp.htm
.Re
.Sh HISTORY
The
.Nm
command appeared in
.Bx 4.3 .
.Pp
Edwin Groothuis <edwin@FreeBSD.org> performed a major rewrite of the
.Xr tftpd 8
and
.Nm
code to support RFC2348.
.Sh NOTES
Because there is no user-login or validation within
the
.Tn 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.
.Pp
Files larger than 33488896 octets (65535 blocks) cannot be transferred
without client and server supporting the TFTP blocksize option (RFC2348),
or the non-standard TFTP rollover option.