pure-ftpd.8

功能强大的ftp服务器源代码

.TP
.B \-x
In normal operation mode, authenticated users can read/write files
beginning with a dot ('.'). Anonymous users can't, for security reasons
(like changing banners or a forgotten .rhosts). When '\-x' is used,
authenticated users can download dot\-files, but not overwrite/create them,
even if they own them. That way, you can prevent hosted users from messing
.qmail files.
.TP
.B \-X
This flag is identical to the previous one (writing dot\-files is
prohibited), but in addition, users can't even *read* files and directories
beginning with a dot (like "cd .ssh").
.TP
.B \-y per user max sessions:max anonymous sessions
This switch enables per-user concurrency limits. Two values are separated by a
column. The first one is the max number of concurrent sessions for a single
login. The second one is the maximum number of anonoymous sessions.
.TP
.B \-Y tls behavior
\fB\-Y 0\fR
(default) disables SSL/TLS security mechanisms.
.br
\fB\-Y 1\fR
Accept both normal sessions and SSL/TLS ones.
.br
\fB\-Y 2\fR
refuses connections that aren't using SSL/TLS security mechanisms, including
anonymous ones.
.br
The server must have been compiled with SSL/TLS support and a valid certificate
must be in place to accept encrypted sessions.
.TP
.B \-z
Allow anonymous users to read files and directories starting with a dot ('.').
.TP
.B \-Z
Add safe guards against common customer mistakes (like chmod 0 on their own files) .


.SH "AUTHENTICATION"
Some of the complexities of older servers are left out.
.PP
This version of pure\-ftpd can use PAM for authentication. If you wan't it to
consult any files like /etc/shells or /etc/ftpd/ftpusers consult pam
docs. LDAP directories and SQL databases are also supported.
.PP
Anonymous users are authenticated in any of three ways:
.PP
1. The user logs in as "ftp" or "anonymous" and there is an
account called "ftp" with an existing home directory. This server
does not ask anonymous users for an email address or other password.
.PP
2. The user connects to an IP address which resolves to the name of a
directory in
.I /etc/pure\-ftpd
(or a symlink in that directory to a real directory), and there is an
account called "ftp" (which does not need to have a valid home
directory). See
.B Virtual Servers
below.
.PP
.B Ftpd
does a
.BR chroot (2)
to the relevant base directory when an anonymous user logs in.
.PP
Note that
.B ftpd
allows remote users to log in as root if the password is known and \-u
not used.

.SH "UNUSUAL FEATURES"
.B Ftpd
never switches uid and euid, it uses
.BR setfsuid (2)
instead. The main reason is that uid switching has been exploited in
several breakins, but the sheer ugliness of uid switching counts too.
.B Ftpd
only calls
.BR setfsuid (2)
once, at login.
.PP
If a user's home directory is \fB/path/to/home/./\fR, FTP sessions under that UID will be chroot()ed. In addition, if a users's home directory is \fB/path/to/home/./directory\fR the session will be chroot()ed to /path/to/home and the FTP session will start in 'directory'.
.PP
As noted above, this
.B pure\-ftpd
omits several features that are required by the RFC or might be
considered useful at first. Here is a list of the most important
omissions.
.PP
On\-the\-fly tar is not supported, for several reasons. I feel that
users who want to get many files should use a special FTP client such
as "mirror," which also supports incremental fetch. I don't want to
either add several hundred lines of code to create tar files or
execute an external tar. Finally, on\-the\-fly tar distorts log files.
.PP
On\-the\-fly compression is left out too. Most files on an FTP site are
compressed already, and if a file isn't, there presumably is a reason
why. (As for decompression: Don't FTP users waste bandwidth enough
without help from on\-the\-fly decompression?)

.SH "DIRECTORY ALIASES"
Shortcuts for the "cd" command can be set up if the server has been compiled
with the \-\-with\-diraliases feature.
.PP
To enable directory aliases, create a file called
.I /etc/pureftpd\-dir\-aliases
and alternate lines of alias names and associated directories.

.SH "ANONYMOUS FTP"
This server leaves out some of the commands and features that have
been used to subvert anonymous FTP servers in the past, but still you
have to be a little bit careful in order to support anonymous FTP
without risk to the rest of your files.
.PP
Make
.I ~ftp
and all files and directories below this directory owned by some user
other than "ftp," and only the
.I .../incoming
directory/directories writable by "ftp." It is probably best if all
directories are writable only by a special group such as "ftpadmin"
and "ftp" is not a member of this group.
.PP
If you do not trust the local users, put
.I ~ftp
on a separate partition, so local users can't hard\-link unapproved
files into the anonymous FTP area.
.PP
Use of the
.B \-s
option is strongly suggested. (Simply add "\-s" to the end of the
.B ftpd
line in
.I /etc/inetd.conf
to enable it.)
.PP
Most other FTP servers require that a number of files such as
.I ~ftp/bin/ls
exist. This server does not require that any files or directories
within
.I ~/ftp
whatsoever exist, and I recommend that all such unnecessary files are
removed (for no real reason).
.PP
It may be worth considering to run the anonymous FTP service as a
virtual server, to get automatic logins and to firewall off the FTP
address/port to which real users can log in.
.PP
If your server is a public FTP site, you may want to allow only 'ftp' and 'anonymous' users to log in. Use the
.B \-e
option for this. Real accounts will be ignored and you will get a secure, anonymous\-only FTP server.

.SH "MAGIC FILES"
The files
.I <ftproot>/.banner
and
.I .message
are magical.
.P
If there is a file called
.I .banner
in the root directory of the anonymous FTP area, or in the root
directory of a virtual host, and it is shorter than 1024 bytes, it is
printed upon login. (If the client does not log in explicitly, and an
implicit login is triggered by a CWD or CDUP command, the banner is
not printed. This is regrettable but hard to avoid.)
.P
If there is a file called
.I .message
in any directory and it is shorter than 1024 bytes, that file is
printed whenever a user enters that directory using CWD or CDUP.

.SH "VIRTUAL SERVERS"
You can run several different anonymous FTP servers on one host, by
giving the host several IP addresses with different DNS names.
.PP
Here are the steps needed to create an extra server using an IP alias
on linux 2.4.x, called "ftp.example.com" on address 10.11.12.13. on
the IP alias eth0.
.PP
1. Create an "ftp" account if you do not have one. It it best if
the account does not have a valid home directory and shell. I prefer
to make
.I /dev/null
the ftp account's home directory and shell.
.B Ftpd
uses this account to set the anonymous users' uid.
.PP
2. Create a directory as described in
.B Anonymous FTP
and make a symlink called
.I /etc/pure\-ftpd/10.11.12.13
which points to this directory.
.PP
3. Make sure your kernel has support for IP aliases.
.PP
4. Make sure that the following commands are run at boot:
.PP
.in +2
/sbin/ifconfig eth0:1 10.11.12.13
.PP
That should be all. If you have problems, here are some things to
try.
.PP
First, symlink
.I /etc/pure\-ftpd/127.0.0.1
to some directory and say "ftp localhost". If that doesn't log you
in, the problem is with
.B ftpd.
.PP
If not, "ping \-v 10.11.12.13" and/or "ping \-v ftp.example.com" from the
same host. If this does not work, the problem is with the IP alias.
.PP
Next, try "ping \-v 10.11.12.13" from a host on the local ethernet, and
afterwards "/sbin/arp \-a". If 10.11.12.13 is listed among the ARP
entries with the correct hardware address, the problem is probably
with the IP alias. If 10.11.12.13 is listed, but has hardware address
0:0:0:0:0:0, then proxy\-ARP isn't working.
.PP
If none of that helps, I'm stumped. Good luck.
.PP
.B Warning:
If you setup a virtual hosts, normal users will not be able to login via
this name, so
.B don't
create link/directory in
.I /etc/pure\-ftpd
for your regular hostname.

.SH "FILES"
.I /etc/passwd
is used via libc (and PAM is this case), to get the uid and home
directory of normal users, the uid and home directory of "ftp" for
normal anonymous ftp, and just the uid of "ftp" for virtual ftp hosts.
.PP
.I /etc/shadow
is used like
.I /etc/passwd
if shadow support is enabled.
.PP
.I /etc/group
is used via libc, to get the group membership of normal users.
.PP
.I /proc/net/tcp
is used to count existing FTP connections, if the
.B \-c
or
.B \-p
options are used
.PP
.I /etc/pure\-ftpd/<ip address>
is the base directory for the <ip address> virtual ftp server, or a
symbolic link to its base directory.
.B Ftpd
does a
.BR chroot (2)
into this directory when a user logs in to <ip address>, thus symlinks
outside this directory will not work.
.PP
.I ~ftp
is the base directory for "normal" anonymous FTP.
.B Ftpd
does a
.BR chroot (2)
into this directory when an anonymous user logs in, thus symlinks
outside this directory will not work.

.SH "LS"
The behaviour of LIST and NLST is a tricky issue. Few servers send
RFC\-compliant responses to LIST, and some clients depend on
non\-compliant responses.
.PP
This server uses
.BR glob (3)
to do filename globbing.
.PP
The response to NLST is by default similar to that of
.BR ls (1),
and
that to LIST is by default similar to that of
.B "ls \-l"
or
.B "ls \-lg"
on most Unix systems, except that the "total" count is meaningless.
Only regular files, directories and symlinks are shown. Only important
.B ls
options are supported:
.TP
.B \-1
Undoes
.BR \-l " and " \-C .
.TP
.B \-a
lists even files/directories whose names begin with ".".
.TP
.B \-C
lists files in as many colums as will fit on the screen. Undoes
.BR \-1 " and " \-l .
.TP
.B \-d
lists argument directories' names rather their contents.
.TP
.B \-D
List files beginning with a dot ('.') even when the client doesn't
append the
.B \-a
option to the
.B list
command.
.TP
.B \-F
appends '*' to executable regular files, '@' to symlinks and '/' to
directories.
.TP
.B \-l
shows various details about the file, including file group. See
.BR ls (1)
for details. Undoes
.BR \-1 " and " \-C .
.TP
.B \-r
reverses the sorting order (modifies
.BR \-S " and " \-t " and the default alphabetical ordering)."
.TP
.B \-R
recursively descends into subdirectories of the argument directories.
.TP
.B \-S
Sorts by file size instead of by name. Undoes
.BR \-t .
.TP
.B \-t
Sorts by file modification time instead of by name. Undoes
.BR \-S .

.SH "PROTOCOL"
Here are the FTP commands supported by this server.
.br
.B ABOR
.B NOOP
.B ALLO
.B USER
.B PASS
.B QUIT
.B SYST
.B PORT
.B EPRT
.B PASV
.B EPSV
.B SPSV
.B PWD
.B XPWD
.B CWD
.B XCWD
.B CDUP
.B XCUP
.B HELP
.B RETR
.B REST
.B DELE
.B STOR
.B APPE
.B STOU
.B MKD
.B XMKD
.B RMD
.B XRMD
.B LIST
.B NLST
.B TYPE
.B MODE
.B STRU
.B XDBG
.B MDTM
.B SIZE
.B RNFR
.B RNTO
.B STAT
.B MLST
.B MLSD
.B FEAT
.B ESTA
.B ESTP
.B AUTH TLS
.B PBSZ
.B PROT
.B SITE IDLE
.B SITE CHMOD
.B SITE HELP
.B SITE TIME

.SH "BUGS"
Please report bugs to the mailing\-list (see below).
Pure\-FTPd looks very stable and is used on production servers. However it comes with no warranty and it can have nasty bugs or security flaws.

.SH "HOME PAGE"
http://www.pureftpd.org/
.SH "NEW VERSIONS"
See the mailing\-list on \fBhttp://www.pureftpd.org/ml/\fR.

.SH "AUTHOR AND LICENSE"
Troll\-FTPd was written by Arnt Gulbrandsen <[e-mail]> and copyright 1995\-2002
Troll Tech AS, Waldemar Thranes gate 98B, N\-0175 Oslo, Norway, fax +47
22806380.
.PP
Pure\-FTPd is (C)opyleft 2001\-2003 by Frank DENIS <[e-mail]> and
the Pure\-FTPd team.
.PP
This software is covered by the BSD license.
.PP
Contributors:
.br
 Arnt Gulbrandsen,
 Troll Tech AS,
 Janos Farkas,
 August Fullford,
 Ximenes Zalteca,
 Patrick Michael Kane,
 Arkadiusz Miskiewicz,
 Michael K. Johnson,
 Kelley Lingerfelt,
 Sebastian Andersson,
 Andreas Westin,
 Jason Lunz,
 Mathias Gumz,
 Claudiu Costin,
 Ping,
 Paul Lasarev,
 Jean\-Mathieux Schaffhauser,
 Emmanuel Hocdet,
 Sami Koskinen,
 Sami Farin,
 Luis Llorente Campo,
 Peter Pentchev,
 Darren Casey,
 The Regents of the University of California,
 Theo de Raadt (OpenBSD),
 Matthias Andree,
 Isak Lyberth,
 Steve Reid,
 RSA Data Security Inc,
 Trilucid,
 Dmtry Lebkov,
 Johan Huisman,
 Thorsten Kukuk,
 Jan van Veen,
 Roger Constantin Demetrescu,
 Stefano F.,
 Robert Varga,
 Freeman,
 James Metcalf,
 Im Eunjea,
 Philip Gladstone,
 Kenneth Stailey,
 Brad Smith,
 Ulrik Sartipy, 
 Cindy Marasco,
 Nicolas Doye,
 Thomas Briggs,
 Stanton Gallegos,
 Florin Andrei,
 Chan Wilson,
 Bjoern Metzdorf,
 Ben Gertzfield,
 Akhilesch Mritunjai,
 Dawid Szymanski,
 Kurt Inge Smadal,
 Alex Dupre,
 Gabriele Vinci,
 Andrey Ulanov,
 Fygul Hether,
 Jeffrey Lim,
 Ying-Chieh Liao,
 Johannes Erdfelt,
 Martin Sarfy,
 Clive Goodhead,
 Aristoteles Pagaltzis,
 Stefan Hornburg,
 Mehmet Cokcevik,
 Brynjar Eide.

.SH "SEE ALSO"
.BR "ftp(1)" ,
.BR "pure-ftpd(8)"
.BR "pure-ftpwho(8)"
.BR "pure-mrtginfo(8)"
.BR "pure-uploadscript(8)"
.BR "pure-statsdecode(8)"
.BR "pure-pw(8)"
.BR "pure-quotacheck(8)"
.BR "pure-authd(8)"

.BR "RFC 959" ,
.BR "RFC 2228",
.BR "RFC 2389" " and"
.BR "RFC 2428" .