You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
152 lines
5.0 KiB
152 lines
5.0 KiB
4 months ago
|
<refentry id="tftpd">
|
||
|
|
|
||
|
|
<refmeta>
|
||
|
|
<refentrytitle>tftpd</refentrytitle>
|
||
|
|
<manvolnum>8</manvolnum>
|
||
|
|
<refmiscinfo>iputils-&snapshot;</refmiscinfo>
|
||
|
|
</refmeta>
|
||
|
|
|
||
|
|
<refnamediv>
|
||
|
|
<refname>tftpd</refname>
|
||
|
|
<refpurpose>Trivial File Transfer Protocol server</refpurpose>
|
||
|
|
</refnamediv>
|
||
|
|
|
||
|
|
<refsynopsisdiv>
|
||
|
|
<cmdsynopsis>
|
||
|
|
<command>tftpd</command>
|
||
|
|
<arg choice="req"><replaceable/directory/</arg>
|
||
|
|
</cmdsynopsis>
|
||
|
|
</refsynopsisdiv>
|
||
|
|
|
||
|
|
<refsect1><title>DESCRIPTION</title>
|
||
|
|
<para>
|
||
|
|
<command/tftpd/ is a server which supports the DARPA
|
||
|
|
Trivial File Transfer Protocol
|
||
|
|
(<ulink url="http://tools.ietf.org/rfc/rfc1350.txt">RFC1350</ulink>).
|
||
|
|
The TFTP server is started
|
||
|
|
by <citerefentry><refentrytitle/inetd/<manvolnum/8/</citerefentry>.
|
||
|
|
</para>
|
||
|
|
|
||
|
|
<para>
|
||
|
|
<replaceable/directory/ is required argument; if it is not given
|
||
|
|
<command/tftpd/ aborts. This path is prepended to any file name requested
|
||
|
|
via TFTP protocol, effectively chrooting <command/tftpd/ to this directory.
|
||
|
|
File names are validated not to escape out of this directory, however
|
||
|
|
administrator may configure such escape using symbolic links.
|
||
|
|
</para>
|
||
|
|
|
||
|
|
<para>
|
||
|
|
It is in difference of variants of <command/tftpd/ usually distributed
|
||
|
|
with unix-like systems, which take a list of directories and match
|
||
|
|
file names to start from one of given prefixes or to some random
|
||
|
|
default, when no arguments were given. There are two reasons not to
|
||
|
|
behave in this way: first, it is inconvenient, clients are not expected
|
||
|
|
to know something about layout of filesystem on server host.
|
||
|
|
And second, TFTP protocol is not a tool for browsing of server's filesystem,
|
||
|
|
it is just an agent allowing to boot dumb clients.
|
||
|
|
</para>
|
||
|
|
|
||
|
|
<para>
|
||
|
|
In the case when <command/tftpd/ is used together with
|
||
|
|
<link linkend="rarpd">
|
||
|
|
<citerefentry><refentrytitle/rarpd/<manvolnum/8/</citerefentry></link>,
|
||
|
|
tftp directories in these services should coincide and it is expected
|
||
|
|
that each client booted via TFTP has boot image corresponding
|
||
|
|
its IP address with an architecture suffix following Sun Microsystems
|
||
|
|
conventions. See
|
||
|
|
<link linkend="rarpd">
|
||
|
|
<citerefentry><refentrytitle/rarpd/<manvolnum/8/</citerefentry></link>
|
||
|
|
for more details.
|
||
|
|
</para>
|
||
|
|
</refsect1>
|
||
|
|
|
||
|
|
<refsect1><title>SECURITY</title>
|
||
|
|
<para>
|
||
|
|
TFTP protocol does not provide any authentication.
|
||
|
|
Due to this capital flaw <command/tftpd/ is not able to restrict
|
||
|
|
access to files and will allow only publically readable
|
||
|
|
files to be accessed. Files may be written only if they already
|
||
|
|
exist and are publically writable.
|
||
|
|
</para>
|
||
|
|
|
||
|
|
<para>
|
||
|
|
Impact is evident, directory exported via TFTP <emphasis/must not/
|
||
|
|
contain sensitive information of any kind, everyone is allowed
|
||
|
|
to read it as soon as a client is allowed. Boot images do not contain
|
||
|
|
such information as rule, however you should think twice before
|
||
|
|
publishing f.e. Cisco IOS config files via TFTP, they contain
|
||
|
|
<emphasis/unencrypted/ passwords and may contain some information
|
||
|
|
about the network, which you were not going to make public.
|
||
|
|
</para>
|
||
|
|
|
||
|
|
<para>
|
||
|
|
The <command/tftpd/ server should be executed by <command/inetd/
|
||
|
|
with dropped root privileges, namely with a user ID giving minimal
|
||
|
|
access to files published in tftp directory. If it is executed
|
||
|
|
as superuser occasionally, <command/tftpd/ drops its UID and GID
|
||
|
|
to 65534, which is most likely not the thing which you expect.
|
||
|
|
However, this is not very essential; remember, only files accessible
|
||
|
|
for everyone can be read or written via TFTP.
|
||
|
|
</para>
|
||
|
|
|
||
|
|
</refsect1>
|
||
|
|
|
||
|
|
|
||
|
|
<refsect1><title>SEE ALSO</title>
|
||
|
|
<para>
|
||
|
|
<link linkend="rarpd">
|
||
|
|
<citerefentry><refentrytitle/rarpd/<manvolnum/8/</citerefentry></link>,
|
||
|
|
<citerefentry><refentrytitle/tftp/<manvolnum/1/</citerefentry>,
|
||
|
|
<citerefentry><refentrytitle/inetd/<manvolnum/8/</citerefentry>.
|
||
|
|
</para>
|
||
|
|
</refsect1>
|
||
|
|
|
||
|
|
<refsect1><title>HISTORY</title>
|
||
|
|
<para>
|
||
|
|
The <command/tftpd/ command appeared in 4.2BSD. The source in iputils
|
||
|
|
is cleaned up both syntactically (ANSIized) and semantically (UDP socket IO).
|
||
|
|
</para>
|
||
|
|
<para>
|
||
|
|
It is distributed with iputils mostly as good demo of an interesting feature
|
||
|
|
(<constant/MSG_CONFIRM/) allowing to boot long images by dumb clients
|
||
|
|
not answering ARP requests until they are finally booted.
|
||
|
|
However, this is full functional and can be used in production.
|
||
|
|
</para>
|
||
|
|
</refsect1>
|
||
|
|
|
||
|
|
|
||
|
|
<refsect1><title>AVAILABILITY</title>
|
||
|
|
<para>
|
||
|
|
<command/tftpd/ is part of <filename/iputils/ package
|
||
|
|
and the latest versions are available in source form at
|
||
|
|
<ulink url="http://www.skbuff.net/iputils/iputils-current.tar.bz2">
|
||
|
|
http://www.skbuff.net/iputils/iputils-current.tar.bz2</ulink>.
|
||
|
|
</para>
|
||
|
|
</refsect1>
|
||
|
|
|
||
|
|
|
||
|
|
<![IGNORE[
|
||
|
|
<refsect1><title>COPYING</title>
|
||
|
|
<para>
|
||
|
|
<literallayout>
|
||
|
|
This documentation is free software; you can redistribute
|
||
|
|
it and/or modify it under the terms of the GNU General Public
|
||
|
|
License Version 2.
|
||
|
|
|
||
|
|
This program is distributed in the hope that it will be
|
||
|
|
useful, but WITHOUT ANY WARRANTY; without even the implied
|
||
|
|
warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
|
||
|
|
See the GNU General Public License for more details.
|
||
|
|
|
||
|
|
For more details see the file COPYING in the source
|
||
|
|
distribution of Linux kernel of version 2.4.
|
||
|
|
</literallayout>
|
||
|
|
</literallayout>
|
||
|
|
</para>
|
||
|
|
</refsect1>
|
||
|
|
]]>
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
</refentry>
|