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34 .\" @(#)ftpd.8 8.2 (Berkeley) 4/19/94
35 .\"
36 .Dd July 19, 2003
37 .Dt FTPD 8
38 .Os BSD 4.2
39 .Sh NAME
40 .Nm ftpd
41 .Nd Internet File Transfer Protocol server
42 .Sh SYNOPSIS
43 .Nm
44 .Op Fl a Ar authmode
45 .Op Fl dilvU
46 .Op Fl g Ar umask
47 .Op Fl p Ar port
48 .Op Fl T Ar maxtimeout
49 .Op Fl t Ar timeout
50 .Op Fl -gss-bindings
51 .Op Fl I | Fl -no-insecure-oob
52 .Op Fl u Ar default umask
53 .Op Fl B | Fl -builtin-ls
54 .Op Fl -good-chars= Ns Ar string
55 .Sh DESCRIPTION
56 .Nm Ftpd
57 is the
58 Internet File Transfer Protocol
59 server process. The server uses the
60 .Tn TCP
61 protocol
62 and listens at the port specified in the
63 .Dq ftp
64 service specification; see
65 .Xr services 5 .
66 .Pp
67 Available options:
68 .Bl -tag -width Ds
69 .It Fl a
70 Select the level of authentication required. Kerberised login can not
71 be turned off. The default is to only allow kerberised login. Other
72 possibilities can be turned on by giving a string of comma separated
73 flags as argument to
74 .Fl a .
75 Recognised flags are:
76 .Bl -tag -width plain
77 .It Ar plain
78 Allow logging in with plaintext password. The password can be a(n) OTP
79 or an ordinary password.
80 .It Ar otp
81 Same as
82 .Ar plain ,
83 but only OTP is allowed.
84 .It Ar ftp
85 Allow anonymous login.
86 .El
87 .Pp
88 The following combination modes exists for backwards compatibility:
89 .Bl -tag -width plain
90 .It Ar none
91 Same as
92 .Ar plain,ftp .
93 .It Ar safe
94 Same as
95 .Ar ftp .
96 .It Ar user
97 Ignored.
98 .El
99 .It Fl d
100 Debugging information is written to the syslog using LOG_FTP.
101 .It Fl g
102 Anonymous users will get a umask of
103 .Ar umask .
104 .It Fl -gss-bindings
105 require the peer to use GSS-API bindings (ie make sure IP addresses match).
106 .It Fl i
107 Open a socket and wait for a connection. This is mainly used for
108 debugging when ftpd isn't started by inetd.
109 .It Fl l
110 Each successful and failed
111 .Xr ftp 1
112 session is logged using syslog with a facility of LOG_FTP.
113 If this option is specified twice, the retrieve (get), store (put), append,
114 delete, make directory, remove directory and rename operations and
115 their filename arguments are also logged.
116 .It Fl p
117 Use
118 .Ar port
119 (a service name or number) instead of the default
120 .Ar ftp/tcp .
121 .It Fl T
122 A client may also request a different timeout period;
123 the maximum period allowed may be set to
124 .Ar timeout
125 seconds with the
126 .Fl T
127 option.
128 The default limit is 2 hours.
129 .It Fl t
130 The inactivity timeout period is set to
131 .Ar timeout
132 seconds (the default is 15 minutes).
133 .It Fl u
134 Set the initial umask to something else than the default 027.
135 .It Fl U
136 In previous versions of
137 .Nm ftpd ,
138 when a passive mode client requested a data connection to the server, the
139 server would use data ports in the range 1024..4999. Now, by default,
140 if the system supports the IP_PORTRANGE socket option, the server will
141 use data ports in the range 49152..65535. Specifying this option will
142 revert to the old behavior.
143 .It Fl v
144 Verbose mode.
145 .It Xo
146 .Fl B ,
147 .Fl -builtin-ls
148 .Xc
149 use built-in ls to list files
150 .It Xo
151 .Fl -good-chars= Ns Ar string
152 .Xc
153 allowed anonymous upload filename chars
154 .It Xo
155 .Fl I
156 .Fl -no-insecure-oob
157 .Xc
158 don't allow insecure out of band.
159 Heimdal ftp clients before 0.6.3 doesn't support secure oob, so turning
160 on this option makes them no longer work.
161 .El
162 .Pp
163 The file
164 .Pa /etc/nologin
165 can be used to disable ftp access.
166 If the file exists,
167 .Nm
168 displays it and exits.
169 If the file
170 .Pa /etc/ftpwelcome
171 exists,
172 .Nm
173 prints it before issuing the
174 .Dq ready
175 message.
176 If the file
177 .Pa /etc/motd
178 exists,
179 .Nm
180 prints it after a successful login.
181 .Pp
182 The ftp server currently supports the following ftp requests.
183 The case of the requests is ignored.
184 .Bl -column "Request" -offset indent
185 .It Request Ta "Description"
186 .It ABOR Ta "abort previous command"
187 .It ACCT Ta "specify account (ignored)"
188 .It ALLO Ta "allocate storage (vacuously)"
189 .It APPE Ta "append to a file"
190 .It CDUP Ta "change to parent of current working directory"
191 .It CWD Ta "change working directory"
192 .It DELE Ta "delete a file"
193 .It HELP Ta "give help information"
194 .It LIST Ta "give list files in a directory" Pq Dq Li "ls -lgA"
195 .It MKD Ta "make a directory"
196 .It MDTM Ta "show last modification time of file"
197 .It MODE Ta "specify data transfer" Em mode
198 .It NLST Ta "give name list of files in directory"
199 .It NOOP Ta "do nothing"
200 .It PASS Ta "specify password"
201 .It PASV Ta "prepare for server-to-server transfer"
202 .It PORT Ta "specify data connection port"
203 .It PWD Ta "print the current working directory"
204 .It QUIT Ta "terminate session"
205 .It REST Ta "restart incomplete transfer"
206 .It RETR Ta "retrieve a file"
207 .It RMD Ta "remove a directory"
208 .It RNFR Ta "specify rename-from file name"
209 .It RNTO Ta "specify rename-to file name"
210 .It SITE Ta "non-standard commands (see next section)"
211 .It SIZE Ta "return size of file"
212 .It STAT Ta "return status of server"
213 .It STOR Ta "store a file"
214 .It STOU Ta "store a file with a unique name"
215 .It STRU Ta "specify data transfer" Em structure
216 .It SYST Ta "show operating system type of server system"
217 .It TYPE Ta "specify data transfer" Em type
218 .It USER Ta "specify user name"
219 .It XCUP Ta "change to parent of current working directory (deprecated)"
220 .It XCWD Ta "change working directory (deprecated)"
221 .It XMKD Ta "make a directory (deprecated)"
222 .It XPWD Ta "print the current working directory (deprecated)"
223 .It XRMD Ta "remove a directory (deprecated)"
224 .El
225 .Pp
226 The following commands are specified by RFC2228.
227 .Bl -column Request -offset indent
228 .It AUTH Ta "authentication/security mechanism"
229 .It ADAT Ta "authentication/security data"
230 .It PROT Ta "data channel protection level"
231 .It PBSZ Ta "protection buffer size"
232 .It MIC Ta "integrity protected command"
233 .It CONF Ta "confidentiality protected command"
234 .It ENC Ta "privacy protected command"
235 .It CCC Ta "clear command channel"
236 .El
237 .Pp
238 The following non-standard or
239 .Tn UNIX
240 specific commands are supported
241 by the
242 SITE request.
243 .Pp
244 .Bl -column Request -offset indent
245 .It UMASK Ta change umask, (e.g.
246 .Ic "SITE UMASK 002" )
247 .It IDLE Ta set idle-timer, (e.g.
248 .Ic "SITE IDLE 60" )
249 .It CHMOD Ta change mode of a file (e.g.
250 .Ic "SITE CHMOD 755 filename" )
251 .It FIND Ta quickly find a specific file with GNU
252 .Xr locate 1 .
253 .It HELP Ta give help information.
254 .El
255 .Pp
256 The following Kerberos related site commands are understood.
257 .Bl -column Request -offset indent
258 .It KAUTH Ta obtain remote tickets.
259 .It KLIST Ta show remote tickets
260 .El
261 .Pp
262 The remaining ftp requests specified in Internet RFC 959
263 are
264 recognized, but not implemented.
265 MDTM and SIZE are not specified in RFC 959, but will appear in the
266 next updated FTP RFC.
267 .Pp
268 The ftp server will abort an active file transfer only when the
269 ABOR
270 command is preceded by a Telnet "Interrupt Process" (IP)
271 signal and a Telnet "Synch" signal in the command Telnet stream,
272 as described in Internet RFC 959.
273 If a
274 STAT
275 command is received during a data transfer, preceded by a Telnet IP
276 and Synch, transfer status will be returned.
277 .Pp
278 .Nm Ftpd
279 interprets file names according to the
280 .Dq globbing
281 conventions used by
282 .Xr csh 1 .
283 This allows users to use the metacharacters
284 .Dq Li \&*?[]{}~ .
285 .Pp
286 .Nm Ftpd
287 authenticates users according to these rules.
288 .Pp
289 .Bl -enum -offset indent
290 .It
291 If Kerberos authentication is used, the user must pass valid tickets
292 and the principal must be allowed to login as the remote user.
293 .It
294 The login name must be in the password data base, and not have a null
295 password (if Kerberos is used the password field is not checked). In
296 this case a password must be provided by the client before any file
297 operations may be performed. If the user has an OTP key, the response
298 from a successful USER command will include an OTP challenge. The
299 client may choose to respond with a PASS command giving either a
300 standard password or an OTP one-time password. The server will
301 automatically determine which type of password it has been given and
302 attempt to authenticate accordingly. See
303 .Xr otp 1
304 for more information on OTP authentication.
305 .It
306 The login name must not appear in the file
307 .Pa /etc/ftpusers .
308 .It
309 The user must have a standard shell returned by
310 .Xr getusershell 3 .
311 .It
312 If the user name appears in the file
313 .Pa /etc/ftpchroot
314 the session's root will be changed to the user's login directory by
315 .Xr chroot 2
316 as for an
317 .Dq anonymous
318 or
319 .Dq ftp
320 account (see next item). However, the user must still supply a password.
321 This feature is intended as a compromise between a fully anonymous account
322 and a fully privileged account. The account should also be set up as for an
323 anonymous account.
324 .It
325 If the user name is
326 .Dq anonymous
327 or
328 .Dq ftp ,
329 an
330 anonymous ftp account must be present in the password
331 file (user
332 .Dq ftp ) .
333 In this case the user is allowed
334 to log in by specifying any password (by convention an email address for
335 the user should be used as the password).
336 .El
337 .Pp
338 In the last case,
339 .Nm ftpd
340 takes special measures to restrict the client's access privileges.
341 The server performs a
342 .Xr chroot 2
343 to the home directory of the
344 .Dq ftp
345 user.
346 In order that system security is not breached, it is recommended
347 that the
348 .Dq ftp
349 subtree be constructed with care, consider following these guidelines
350 for anonymous ftp.
351 .Pp
352 In general all files should be owned by
353 .Dq root ,
354 and have non-write permissions (644 or 755 depending on the kind of
355 file). No files should be owned or writable by
356 .Dq ftp
357 (possibly with exception for the
358 .Pa ~ftp/incoming ,
359 as specified below).
360 .Bl -tag -width "~ftp/pub" -offset indent
361 .It Pa ~ftp
362 The
363 .Dq ftp
364 homedirectory should be owned by root.
365 .It Pa ~ftp/bin
366 The directory for external programs (such as
367 .Xr ls 1 ) .
368 These programs must either be statically linked, or you must setup an
369 environment for dynamic linking when running chrooted.
370 These programs will be used if present:
371 .Bl -tag -width "locate" -offset indent
372 .It ls
373 Used when listing files.
374 .It compress
375 When retrieving a filename that ends in
376 .Pa .Z ,
377 and that file isn't present,
378 .Nm
379 will try to find the filename without
380 .Pa .Z
381 and compress it on the fly.
382 .It gzip
383 Same as compress, just with files ending in
384 .Pa .gz .
385 .It gtar
386 Enables retrieval of whole directories as files ending in
387 .Pa .tar .
388 Can also be combined with compression. You must use GNU Tar (or some
389 other that supports the
390 .Fl z
391 and
392 .Fl Z
393 flags).
394 .It locate
395 Will enable ``fast find'' with the
396 .Ic SITE FIND
397 command. You must also create a
398 .Pa locatedb
399 file in
400 .Pa ~ftp/etc .
401 .El
402 .It Pa ~ftp/etc
403 If you put copies of the
404 .Xr passwd 5
405 and
406 .Xr group 5
407 files here, ls will be able to produce owner names rather than
408 numbers. Remember to remove any passwords from these files.
409 .Pp
410 The file
411 .Pa motd ,
412 if present, will be printed after a successful login.
413 .It Pa ~ftp/dev
414 Put a copy of
415 .Xr /dev/null 7
416 here.
417 .It Pa ~ftp/pub
418 Traditional place to put whatever you want to make public.
419 .El
420 .Pp
421 If you want guests to be able to upload files, create a
422 .Pa ~ftp/incoming
423 directory owned by
424 .Dq root ,
425 and group
426 .Dq ftp
427 with mode 730 (make sure
428 .Dq ftp
429 is member of group
430 .Dq ftp ) .
431 The following restrictions apply to anonymous users:
432 .Bl -bullet
433 .It
434 Directories created will have mode 700.
435 .It
436 Uploaded files will be created with an umask of 777, if not changed
437 with the
438 .Fl g
439 option.
440 .It
441 These command are not accessible:
442 .Ic DELE , RMD , RNTO , RNFR ,
443 .Ic SITE UMASK ,
444 and
445 .Ic SITE CHMOD .
446 .It
447 Filenames must start with an alpha-numeric character, and consist of
448 alpha-numeric characters or any of the following:
449 .Li \&+
450 (plus),
451 .Li \&-
452 (minus),
453 .Li \&=
454 (equal),
455 .Li \&_
456 (underscore),
457 .Li \&.
458 (period), and
459 .Li \&,
460 (comma).
461 .El
462 .Sh FILES
463 .Bl -tag -width /etc/ftpwelcome -compact
464 .It Pa /etc/ftpusers
465 Access list for users.
466 .It Pa /etc/ftpchroot
467 List of normal users who should be chroot'd.
468 .It Pa /etc/ftpwelcome
469 Welcome notice.
470 .It Pa /etc/motd
471 Welcome notice after login.
472 .It Pa /etc/nologin
473 Displayed and access refused.
474 .It Pa ~/.klogin
475 Login access for Kerberos.
476 .El
477 .Sh SEE ALSO
478 .Xr ftp 1 ,
479 .Xr otp 1 ,
480 .Xr getusershell 3 ,
481 .Xr ftpusers 5 ,
482 .Xr syslogd 8
483 .Sh STANDARDS
484 .Bl -tag -compact -width "RFC 1938"
485 .It Cm RFC 959
486 FTP PROTOCOL SPECIFICATION
487 .It Cm RFC 1938
488 OTP Specification
489 .It Cm RFC 2228
490 FTP Security Extensions.
491 .El
492 .Sh BUGS
493 The server must run as the super-user
494 to create sockets with privileged port numbers. It maintains
495 an effective user id of the logged in user, reverting to
496 the super-user only when binding addresses to sockets. The
497 possible security holes have been extensively
498 scrutinized, but are possibly incomplete.
499 .Sh HISTORY
500 The
501 .Nm
502 command appeared in
503 .Bx 4.2 .