1OPIE Software Distribution, Release 2.4 Important Information
2======================================= =====================
3
4Introduction
5============
6
7 "One-time Passwords In Everything" (OPIE) is a freely distributable
8software package originally developed at and for the US Naval Research
9Laboratory (NRL). Recent versions are the result of a cooperative effort
10between of NRL, several of the original NRL authors, The Inner Net, and many
11other contributors from the Internet community.
12
13 OPIE is an implementation of the One-Time Password (OTP) System that
14is being considered for the Internet standards-track. OPIE provides a one-time
15password system. The system should be secure against the passive attacks
16now commonplace on the Internet (see RFC 1704 for more details). The system
17is vulnerable to active dictionary attacks, though these are not widespread
18at present and can be detected through proper use of system audit
19software.
20
21 OPIE is primarily written for UNIX-like operating systems, but
22we are working to make applicable portions portable to other operating systems.
23The OPIE software is derived in part from and is fully interoperable with the
24Bell Communications Research (Bellcore) S/Key Release 1 software. Because
25Bellcore claims "S/Key" as a trademark for their software, NRL was forced to
26use a different name (we picked "OPIE") for this software distribution.
27
28 OPIE includes the following additions/modifications to the
29original Bellcore S/Key(tm) Version 1 software:
30
31* Just about three command installation (unpack the software, run the
32 configure script, and run make install). While we still recommend that you
33 follow instructions and test things by hand, the more adventurous can
34 install OPIE quickly.
35
36* A modified BSD FTP daemon that does OTP.
37
38* A version of su that uses OTP by default.
39
40* MD5 support. MD5 is now the default algorithm, though MD4 is still supported
41 by changing a parameter in the Makefile. This change was made because MD5 is
42 widely believed to be cryptographically stronger than MD4 (see RFC 1321).
43
44* A more portable version of MD4 has been substituted for the original MD4.
45 This should solve the endian problems that were in S/Key.
46
47* Most of the system-dependencies have been moved to a new file "opie_cfg.h".
48
49* Configuration options have been moved to the Makefile.
50
51* Isolated system dependencies (e.g. BSDisms) with appropriate #ifdefs.
52
53* Revised the opiekey(1) program to simultaneously support MD4 and MD5, with
54 the default algorithm being tunable using the MDX symbol in the Makefile.
55
56* More operating systems are supported by recent versions of OPIE, but older
57 BSD systems that aren't close to being compliant with the POSIX standard are
58 no longer supported.
59
60* Transition mechanisms are optional to prevent potential back doors.
61
62* On systems using the /etc/opieaccess transition mechanism, users can choose
63 to require the use of OPIE to login to their accounts when it would
64 otherwise be optional.
65
66* Bug fixes
67
68* Cosmetic changes
69
70* Prompts (optionally) identify specifically what kind of entry (system
71 password, secret pass phrase, or OTP response) is allowed.
72
73* Changes to mostly conform with the draft Internet OTP standard.
74
75A Glance at What's New
76======================
77
78 2.4 TEST VERSION -- NOT FOR REDISTRIBUTION
79
80 Merged in opieauto, which is disabled by default.
81
82 Lots of documentation updates.
83
84 Portability and bug fixes.
85
86 2.32 January 1, 1998.
87
88 Indicate support for extended responses in challenges and check for such
89indication before generating any extended responses.
90
91 Lots of portability and bug fixes.
92
93 2.31 March 20, 1997.
94
95 Removed active attack protection support due to patent problems.
96
97 Removed the supplemental key file; it did more harm than good.
98
99 Moved user locks to a separate directory.
100
101 Moved user-serviceable configuration options to the configure script.
102
103 Lots of portability and bug fixes.
104
105 2.3 September 22, 1996
106
107 Autoconf is now the only supported configuration method.
108
109 Lots of internal functions got re-written in ways that will make some
110planned future changes easier.
111
112 OTP extended responses, such as automatic re-initialization.
113
114 Support for a supplemental key file that stores information that was not
115in the original /etc/skeykeys file. This allows OPIE to store extra data needed
116for things like the OTP re-initialization extended response without breaking
117interoperability with other S/Key derived programs. This file is named
118"/etc/opiekeys.ext" by default. Unlike the standard key file, it MUST NOT be
119world readable.
120
121 OPIE should better support some of the native "features" of drain bamaged
122OSs such as AIX, HP-UX, and Solaris.
123
124 OPIE's utmp/wtmp handling has been completely re-written. This should solve
125many of the utmp/wtmp problems people have been having.
126
127 Lots of cleanups.
128
129 Bug fixes.
130
131 2.22 May 3, 1996.
132
133 More minor bug fixes. OPIE once again works on Solaris 2.x.
134
135 2.21 April 27, 1996.
136
137 Minor bug fixes.
138
139 2.2 April 11, 1996.
140
141 opiesubr.c, opiesubr2.c, and a few other functions moved into a
142subdirectory and split into files with fine granularity. Ditto with missing
143function replacements. This subdirectory structure changes a lot of things
144around and more splitting like this should be expected in the near future.
145
146 Added opiegenerator() library function that should make it very easy to
147create OTP clients using the OPIE library (this function is subject to change:
148there are a few problems remaining to be solved). Just about re-wrote
149opiegetpass() to use raw I/O and got most of the OPIE programs actually using
150that function. Autoconf build fixes. Lots of bug fixes. Lots of portability
151fixes. Function declarations should be ANSI style for ANSI compilers. Several
152fixes to bring OPIE in line with the latest OTP spec. MJR DES key crunch
153de-implemented.
154
155 Added sample programs: opiegen (client) and opieserv (server).
156
157 Probably broke non-autoconf support along the way :(. I've tried to bring
158this back in sync, but it may still be broken.
159
160 2.11 December 27, 1995.
161
162 Minor bug fixes.
163
164 2.10 December 26, 1995.
165
166 Optional autoconf support. opieinfo is now a normal program. Bugs fixed --
167should work much better on SunOS, HP-UX, and AIX.
168
169 2.01 -- 2.04
170
171 Bug fix releases.
172
173 2.00
174
175 Initial release of OPIE 2.0.
176
177System Requirements
178===================
179
180 In order to build and run properly, OPIE requires:
181
182 * A UNIX-like operating system
183 * An ANSI C compiler and run-time library
184 * POSIX.1- and X/Open XPG-compliance (including termios)
185 * The BSD sockets API
186 * Approximately five megabytes of free disk space
187
188 In practice, we believe that many systems who are close to meeting
189these requirements but aren't completely there (for example, SunOS with the
190native compiler) will also work. Systems who aren't anywhere near close
191(for example, DOS) are not likely to work without major adjustments to the
192OPIE code.
193
194If OPIE Doesn't Work
195====================
196
197 Under NO circumstances should you send trouble reports directly to the
198authors or contributors. They WILL BE IGNORED.
199
200 Make sure you have the latest version of OPIE. The latest version is
201available by HTTP at:
202
203 http://www.inner.net/pub/opie
204
205 (sorry, but anonymous FTP is no longer available)
206
207 If you have installed the OPIE software (either through "make test"
208in (7) above or "make install" in (14)), you can run "make uninstall" from the
209OPIE software distribution directory. This should remove the OPIE software and
210restore the original system programs, but it will not work properly (and can
211even result in the total loss of the old system programs -- beware!) if the
212installation procedure itself did not work properly.
213
214 If you are running a release version, try installing the latest public
215test version (look around). These frequently have already fixed the problem
216you are seeing, but may have new problems of their own (that's why they're
217test versions!). Similarly, if you are running a test version, try installing
218the latest released version.
219
220 OPIE is NOT supported software. We don't promise to support you or
221even to acknowledge your mail, but we are interested in bug reports and are
222reasonable folks. We also have an interest in seeing OPIE work on as many
223systems as we can. However, if your system doesn't meet the basic requirements
224for OPIE, this will probably require an unreasonable amount of effort.
225
226 The best bug reports include a diagnosis of the problem and a fix.
227Your bug report can still be valuable if you can at least diagnose what the
228problem is. If you just tell us "it doesn't work," then we won't be able to
229do anything to help you.
230
231 We've received a number of bug reports from people that look
232interesting, only to find when we try to follow up on them that the user
233either has an invalid return address or never bothered to respond to our
234followup. Please make sure that bug reports you send us have an electronic
235mail address that we can reply to somewhere in them (if necessary, just
236put it in the message body). If we send you a response and you are unable
237to invest the time to work with us to solve the problem, please tell us --
238few things are more irritating than when someone sends us information
239about a bug that we'd like to fix and then is never heard from again.
240
241 We try to respond to all properly submitted bug reports. Improperly
242submitted bug reports will be responded to only if we have time left after
243responding to properly submitted bug reports. We deliberately ignore bug
244"reports" sent to mailing lists or USENET news groups instead of or before
245our bug report address. At the least, the latter practice is lacking in
246courtesy.
247
248 The file BUG-REPORT contains our bug reporting form. Please use it
249and follow the submission instructions in that file. We are going to switch
250to machine-parsed bug report processing sometime in the near future to make
251it easier to coordinate bug hunting.
252
253Gotchas
254=======
255
256 Solaris 2.x is just a lose. It does a lot of nonstandard and downright
257broken things. If you want OPIE to be reliable on your box, upgrade to OpenBSD
258or Linux.
259
260 While an almost universal "feature", most people remain unaware that
261an intruder can log into a system, then log in again by running the "login"
262command from a shell. Because the second login is from the local host, the
263utmp entry will not show a remote login host anymore. The OPIE replacement
264for /bin/login currently carries on this behavior for compatibility reasons.
265If you would like to prevent this from happening, you should change the
266permissions of /bin/login to 0100, thus preventing unprivileged users from
267executing it. This fix should work on non-OPIE /bin/login programs as well.
268
269 On 4.3BSDish systems, the supplied /bin/login replacement obtains
270the terminal type for the console comes from the console line in the /etc/ttys
271file. Several systems contain a default entry in this file that specifies the
272console terminal type as "unknown". This is probably not what you want.
273
274 The OPIE FTP daemon responds with two 530 error messages if you have
275not yet logged in and execute a command that will also do a PORT request. This
276is a feature, not a bug, as the FTP client is really sending the server two
277commands (for instance, a PORT and a LIST if you tell your BSD FTP client to do
278a DIR command) and the server is responding to each of them with an error. The
279stock BSD FTP daemon doesn't check the PORT commands to see if you are logged
280in, so you would only get one error message. This change should not break any
281standards-compliant FTP client, but there are a number of brain-damaged GUI
282clients that have a track record for not dealing gracefully with any server
283other than the stock BSD one.
284
285 The /etc/opieaccess transition mechanism is, by definition, a security
286hole in the OPIE software because an attacker could use it to circumvent the
287requirement for OPIE authentication. You should compile the software with
288support for this file disabled unless you absolutely cannot use the software
289without it because of your environment. If you do use this support for
290transition purposes, you should move people to OTP authentication as quickly
291as possible and rebuild and reinstall OPIE with this transition support
292disabled so that you won't have a lurking security hole.
293
294 If this wasn't already clear, do not let your sequence number fall
295below about ten. If your sequence number reaches zero, your OTP sequence
296can only be reset by the superuser. System administrators should make this
297caveat known to their users.
298
299 On Solaris 2.x systems (and possibly others) running NIS+, users
300should run keylogin(1) manually after login because opielogin(1) does not
301do that automatically like the system login(1) program.
302
303 There are reports that some versions of GNU C Compiler (GCC)
304(when installed on some systems) use their own termios(4) instead of
305the system's termios(4). This can cause problems. If you are having
306compilation problems that seem to relate to termios and you are using
307GCC, you should probably verify that it is using the system's
308termios(4) and not some internal-to-GCC termios(4). One report
309indicates that Sun's C compiler works fine with SunOS 4.1.3/4.1.4 on
310SPARC, but that some version of GCC on the same system has this
311termios(4) problem. We haven't reproduced these problems ourselves
312and hence aren't sure what is happening, but we pass this along for
313your information. (This may have something to do with the use of GNU
314libc)
315
316 If a user has a valid entry in the opiekeys database but has an
317asterisk in their traditional password entry, they will not be able to
318log in via opielogin, but opielogin will decrement their sequence number
319if a valid response is received.
320
321 On some systems, the OPIE login program does not always display
322a "login:" prompt the first time. There is a race condition in many older
323telnetds that is probably the cause of this problem. This should be fixed by
324replacing your telnetd with the latest version of the stock telnetd
325(ftp.cray.com:/src/telnet).
326
327 The standard HPUX compiler is severely drain bamaged. One of the
328worst parts is that it sometimes won't grok a symbol definition with forward
329slashes in them properly and can choke badly on the definition of the key
330file's location. If this happens to you, install and use GCC. (This problem
331may or may not also come up with the optional HP ANSI C compiler -- we don't
332know for sure what compilers have this problem).
333
334 As of OPIE 2.2, the seed is converted to lower case and its length is
335checked in order to comply with the OTP specification. If any of your users
336have seeds that use capital letters or are too long, they need to run the OPIE
3372.2 opiepasswd program to re-initialize their sequence to one with a different
338seed.
339
340 opielogin is a replacement for /bin/login. It is NOT an OPIE "shell."
341You can use it as one, but don't be surprised if it doesn't behave the way
342you expect -- we've seen various reports of success and failure when used this
343way. An OPIE "shell" is on the TODO list.
344
345 Clients that use opiegen() will automatically send a re-initialization
346extended response if the sequence number falls below ten. If the server does
347not support this, the user will need to log in using opiekey and reset his
348sequence manually (using opiepasswd).
349
350 For reasons that remain very unclear, Solaris passes the login name
351from getty/telnetd to login by stuffing it in the terminal input buffer
352instead of passing it on the command line like every other *IX. This is just
353plain broken. Solaris has other problems with its telnetd and getty; you may
354want to consider getting the telnet(d) sources (ftp.cray.com:/src/telnet)
355and reasonable getty sources (try sunsite.unc.edu:/pub/Linux/system/Serial, at
356least one of agetty, mingetty, and getty_ps should work) and replacing the
357Solaris versions with these. OPIE should work *much* more happily with these
358programs than the ones that come with Solaris. However, there could be negative
359side effects -- this is not a procedure recommended for the faint of heart.
360
361 OPIE is a lot more fussy than it used to be about lock files and where
362it puts them. The lock file directory must be a directory used only for OPIE
363lock files. It must be a directory, owned by the superuser, and must be mode
3640700.
365
366 opieauto is a potential security hole. It opens a limited window of
367exposure by transmitting and storing information that can be used to
368generate one or more OTPs earlier than the current sequence number. Every
369effort has been made to limit the potential for compromise to the user-
370specified window. However, an attacker with superuser priveleges or access to
371your account on the client system can still generate OTPs based on the
372information cached via opieauto. In practice, there are other ways for such an
373an attacker to get your entire secret pass phrase, so this is probably not
374creating a significant new security problem. However, because of this
375potential for problems and because opieauto uses system features that are not
376present on all systems, opieauto support is not compiled in by default and
377must be specifically enabled at compile time.
378
379 Many users are running OPIE with the key file on a shared NFS volume
380in order to use OTP as a single-login system for a cluster of machines. OPIE
381was NOT designed to be operated this way, though it does seem to work. If it
382fails or if this proves insecure, this is not OPIE's fault. Note that, if you
383do this, you probably want to share the OPIE lock files too.
384
385Gripes
386======
387
388 Is it too much to ask that certain OS vendors just do the right thing
389and not "fix" what isn't broken? (Look at all the ifdefs in the OPIE code and
390the answer is clear)
391
392 utmp and wtmp handling in OPIE has been a very, very sore subject.
393Every vendor does things differently, and, of course, most of them swear they
394are complying to some or other "standard." My (cmetz) conclusion is that the
395only thing that is standard about utmp and wtmp handling is that it will be
396nonstandard on any given system. I've tried a lot of things and I've wasted
397*a lot* of time on trying to make utmp and wtmp handling work for everybody;
398my conclusion is that it will never happen. While I am still interested in
399hearing about fixes for utmp/wtmp on systems where they don't work, I'm not
400likely to go out of my way to fix utmp/wtmp handling. If you want it fixed,
401the best way to do it is to fix it yourself and contribute a patch. As long as
402the patch is reasonable, it will be included in the next release. If you can't
403wait, use the --disable-utmp option.
404
405Credits
406=======
407
408 First and foremost credit goes to Phil Karn, Neil M. Haller, and John
409S. Walden of Bellcore for creating the S/Key Version 1 software distribution
410and for making its source code freely available to the public. Without their
411work, OPIE would not exist. Neil has also invested a good amount of his time
412in the development of a standard for One-Time Passwords so that packages like
413OPIE can interoperate.
414
415 The first NRL OPIE distribution included modifications made primarily
416by Dan McDonald of the U.S. Naval Research Laboratory (NRL) during March 1994.
417The 2nd NRL OPIE distribution, which has a number of improvements in areas
418such as portability of software and ease of installation, is primarily the
419work of Ran Atkinson and Craig Metz. Other NRL contributors include Brian
420Adamson, Steve Batsell, Preston Mullen, Bao Phan, Jim Ramsey, and Georg Thomas.
421
422 Some of version 2.2 was developed at NRL and released as a work in
423progress. Most of the release version was developed by Craig Metz (also of
424NRL), others at The Inner Net, and contributors from the Internet community.
425Versions beyond 2.2 were developed outside NRL, so don't blame them if they
426don't work (But please credit them when it does. Without the NRL effort, there
427wouldn't be an OPIE).
428
429 We would like to also thank everyone who helped us by by beta testing,
430reporting bugs, suggesting improvements, and/or sending us patches. We
431appreciate your contributions -- they have helped to make OPIE more of a
432community effort. These contributors include:
433
434 Mowgli Assor
435 Lawrie Brown
436 Andrew Davis
437 Taso N. Devetzis
438 Carson Gaspar
439 Dennis Glatting
440 Ben Golding
441 Axel Grewe
442 "Hobbit"
443 Kojima Hajime
444 Darren Hosking
445 Matt Hucke
446 Kenji Kamizono
447 Charles Karney
448 Jeff Kletsky
449 Peter Koch
450 Martijn Koster
451 Osamu Kurati
452 Ayamura Kikuchi
453 Ronald van der Meer
454 Bret Musser
455 Hiroshi Nakano
456 Ikuo Nakagawa
457 Angelo Neri
458 C. R. Oldham
459 Ossama Othman
460 D. Jason Penney
461 John Perkins
462 Steve Price
463 Jim Simmons
464 Steve Simmons
465 Brad Smith
466 Werner Wiethege
467 Ken-ichi Yamasaki
468 Wietse Venema
469
470 OPIE development at NRL was sponsored by the Information Security
471Program Office (PD 71E), U.S. Space and Naval Warfare Systems Command, Crystal
472City, Virginia.
473
474 If you have problems with OPIE, please follow the instructions under
475"If OPIE Doesn't Work." Under NO circumstances should you send trouble
476reports directly to the authors or contributors. They WILL BE IGNORED.
477
478Trademarks
479==========
480S/Key is a trademark of Bell Communications Research (Bellcore).
481UNIX is a trademark of X/Open.
482NRL is a trademark of the U. S. Naval Research Laboratory.
483
484All other trademarks are trademarks of their respective owners.
485
486The term "OPIE" is in the public domain and hence cannot be legally
487trademarked by anyone. Please do not abuse it.
488
489Copyrights
490==========
491%%% portions-copyright-cmetz-96
492Portions of this software are Copyright 1996-1999 by Craig Metz, All Rights
493Reserved. The Inner Net License Version 2 applies to these portions of
494the software.
495You should have received a copy of the license with this software. If
496you didn't get a copy, you may request one from <license@inner.net>.
497
498Portions of this software are Copyright 1995 by Randall Atkinson and Dan
499McDonald, All Rights Reserved. All Rights under this copyright are assigned
500to the U.S. Naval Research Laboratory (NRL). The NRL Copyright Notice and
501License Agreement applies to this software.
502
503Portions of this software are copyright 1980-1990 Regents of the
504University of California, all rights reserved. The Berkeley Software
505License Agreement specifies the terms and conditions for redistribution.
506
507Portions of this software are copyright 1990 Bell Communications Research
508(Bellcore), all rights reserved.
509