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OPIE Software Distribution, Release 2.4 Important Information ======================================= ===================== Introduction ============ "One-time Passwords In Everything" (OPIE) is a freely distributable software package originally developed at and for the US Naval Research Laboratory (NRL). Recent versions are the result of a cooperative effort between of NRL, several of the original NRL authors, The Inner Net, and many other contributors from the Internet community. OPIE is an implementation of the One-Time Password (OTP) System that is being considered for the Internet standards-track. OPIE provides a one-time password system. The system should be secure against the passive attacks now commonplace on the Internet (see RFC 1704 for more details). The system is vulnerable to active dictionary attacks, though these are not widespread at present and can be detected through proper use of system audit software. OPIE is primarily written for UNIX-like operating systems, but we are working to make applicable portions portable to other operating systems. The OPIE software is derived in part from and is fully interoperable with the Bell Communications Research (Bellcore) S/Key Release 1 software. Because Bellcore claims "S/Key" as a trademark for their software, NRL was forced to use a different name (we picked "OPIE") for this software distribution. OPIE includes the following additions/modifications to the original Bellcore S/Key(tm) Version 1 software: * Just about three command installation (unpack the software, run the configure script, and run make install). While we still recommend that you follow instructions and test things by hand, the more adventurous can install OPIE quickly. * A modified BSD FTP daemon that does OTP. * A version of su that uses OTP by default. * MD5 support. MD5 is now the default algorithm, though MD4 is still supported by changing a parameter in the Makefile. This change was made because MD5 is widely believed to be cryptographically stronger than MD4 (see RFC 1321). * A more portable version of MD4 has been substituted for the original MD4. This should solve the endian problems that were in S/Key. * Most of the system-dependencies have been moved to a new file "opie_cfg.h". * Configuration options have been moved to the Makefile. * Isolated system dependencies (e.g. BSDisms) with appropriate #ifdefs. * Revised the opiekey(1) program to simultaneously support MD4 and MD5, with the default algorithm being tunable using the MDX symbol in the Makefile. * More operating systems are supported by recent versions of OPIE, but older BSD systems that aren't close to being compliant with the POSIX standard are no longer supported. * Transition mechanisms are optional to prevent potential back doors. * On systems using the /etc/opieaccess transition mechanism, users can choose to require the use of OPIE to login to their accounts when it would otherwise be optional. * Bug fixes * Cosmetic changes * Prompts (optionally) identify specifically what kind of entry (system password, secret pass phrase, or OTP response) is allowed. * Changes to mostly conform with the draft Internet OTP standard. A Glance at What's New ====================== 2.4 TEST VERSION -- NOT FOR REDISTRIBUTION Merged in opieauto, which is disabled by default. Lots of documentation updates. Portability and bug fixes. 2.32 January 1, 1998. Indicate support for extended responses in challenges and check for such indication before generating any extended responses. Lots of portability and bug fixes. 2.31 March 20, 1997. Removed active attack protection support due to patent problems. Removed the supplemental key file; it did more harm than good. Moved user locks to a separate directory. Moved user-serviceable configuration options to the configure script. Lots of portability and bug fixes. 2.3 September 22, 1996 Autoconf is now the only supported configuration method. Lots of internal functions got re-written in ways that will make some planned future changes easier. OTP extended responses, such as automatic re-initialization. Support for a supplemental key file that stores information that was not in the original /etc/skeykeys file. This allows OPIE to store extra data needed for things like the OTP re-initialization extended response without breaking interoperability with other S/Key derived programs. This file is named "/etc/opiekeys.ext" by default. Unlike the standard key file, it MUST NOT be world readable. OPIE should better support some of the native "features" of drain bamaged OSs such as AIX, HP-UX, and Solaris. OPIE's utmp/wtmp handling has been completely re-written. This should solve many of the utmp/wtmp problems people have been having. Lots of cleanups. Bug fixes. 2.22 May 3, 1996. More minor bug fixes. OPIE once again works on Solaris 2.x. 2.21 April 27, 1996. Minor bug fixes. 2.2 April 11, 1996. opiesubr.c, opiesubr2.c, and a few other functions moved into a subdirectory and split into files with fine granularity. Ditto with missing function replacements. This subdirectory structure changes a lot of things around and more splitting like this should be expected in the near future. Added opiegenerator() library function that should make it very easy to create OTP clients using the OPIE library (this function is subject to change: there are a few problems remaining to be solved). Just about re-wrote opiegetpass() to use raw I/O and got most of the OPIE programs actually using that function. Autoconf build fixes. Lots of bug fixes. Lots of portability fixes. Function declarations should be ANSI style for ANSI compilers. Several fixes to bring OPIE in line with the latest OTP spec. MJR DES key crunch de-implemented. Added sample programs: opiegen (client) and opieserv (server). Probably broke non-autoconf support along the way :(. I've tried to bring this back in sync, but it may still be broken. 2.11 December 27, 1995. Minor bug fixes. 2.10 December 26, 1995. Optional autoconf support. opieinfo is now a normal program. Bugs fixed -- should work much better on SunOS, HP-UX, and AIX. 2.01 -- 2.04 Bug fix releases. 2.00 Initial release of OPIE 2.0. System Requirements =================== In order to build and run properly, OPIE requires: * A UNIX-like operating system * An ANSI C compiler and run-time library * POSIX.1- and X/Open XPG-compliance (including termios) * The BSD sockets API * Approximately five megabytes of free disk space In practice, we believe that many systems who are close to meeting these requirements but aren't completely there (for example, SunOS with the native compiler) will also work. Systems who aren't anywhere near close (for example, DOS) are not likely to work without major adjustments to the OPIE code. If OPIE Doesn't Work ==================== Under NO circumstances should you send trouble reports directly to the authors or contributors. They WILL BE IGNORED. Make sure you have the latest version of OPIE. The latest version is available by HTTP at: http://www.inner.net/pub/opie (sorry, but anonymous FTP is no longer available) If you have installed the OPIE software (either through "make test" in (7) above or "make install" in (14)), you can run "make uninstall" from the OPIE software distribution directory. This should remove the OPIE software and restore the original system programs, but it will not work properly (and can even result in the total loss of the old system programs -- beware!) if the installation procedure itself did not work properly. If you are running a release version, try installing the latest public test version (look around). These frequently have already fixed the problem you are seeing, but may have new problems of their own (that's why they're test versions!). Similarly, if you are running a test version, try installing the latest released version. OPIE is NOT supported software. We don't promise to support you or even to acknowledge your mail, but we are interested in bug reports and are reasonable folks. We also have an interest in seeing OPIE work on as many systems as we can. However, if your system doesn't meet the basic requirements for OPIE, this will probably require an unreasonable amount of effort. The best bug reports include a diagnosis of the problem and a fix. Your bug report can still be valuable if you can at least diagnose what the problem is. If you just tell us "it doesn't work," then we won't be able to do anything to help you. We've received a number of bug reports from people that look interesting, only to find when we try to follow up on them that the user either has an invalid return address or never bothered to respond to our followup. Please make sure that bug reports you send us have an electronic mail address that we can reply to somewhere in them (if necessary, just put it in the message body). If we send you a response and you are unable to invest the time to work with us to solve the problem, please tell us -- few things are more irritating than when someone sends us information about a bug that we'd like to fix and then is never heard from again. We try to respond to all properly submitted bug reports. Improperly submitted bug reports will be responded to only if we have time left after responding to properly submitted bug reports. We deliberately ignore bug "reports" sent to mailing lists or USENET news groups instead of or before our bug report address. At the least, the latter practice is lacking in courtesy. The file BUG-REPORT contains our bug reporting form. Please use it and follow the submission instructions in that file. We are going to switch to machine-parsed bug report processing sometime in the near future to make it easier to coordinate bug hunting. Gotchas ======= Solaris 2.x is just a lose. It does a lot of nonstandard and downright broken things. If you want OPIE to be reliable on your box, upgrade to OpenBSD or Linux. While an almost universal "feature", most people remain unaware that an intruder can log into a system, then log in again by running the "login" command from a shell. Because the second login is from the local host, the utmp entry will not show a remote login host anymore. The OPIE replacement for /bin/login currently carries on this behavior for compatibility reasons. If you would like to prevent this from happening, you should change the permissions of /bin/login to 0100, thus preventing unprivileged users from executing it. This fix should work on non-OPIE /bin/login programs as well. On 4.3BSDish systems, the supplied /bin/login replacement obtains the terminal type for the console comes from the console line in the /etc/ttys file. Several systems contain a default entry in this file that specifies the console terminal type as "unknown". This is probably not what you want. The OPIE FTP daemon responds with two 530 error messages if you have not yet logged in and execute a command that will also do a PORT request. This is a feature, not a bug, as the FTP client is really sending the server two commands (for instance, a PORT and a LIST if you tell your BSD FTP client to do a DIR command) and the server is responding to each of them with an error. The stock BSD FTP daemon doesn't check the PORT commands to see if you are logged in, so you would only get one error message. This change should not break any standards-compliant FTP client, but there are a number of brain-damaged GUI clients that have a track record for not dealing gracefully with any server other than the stock BSD one. The /etc/opieaccess transition mechanism is, by definition, a security hole in the OPIE software because an attacker could use it to circumvent the requirement for OPIE authentication. You should compile the software with support for this file disabled unless you absolutely cannot use the software without it because of your environment. If you do use this support for transition purposes, you should move people to OTP authentication as quickly as possible and rebuild and reinstall OPIE with this transition support disabled so that you won't have a lurking security hole. If this wasn't already clear, do not let your sequence number fall below about ten. If your sequence number reaches zero, your OTP sequence can only be reset by the superuser. System administrators should make this caveat known to their users. On Solaris 2.x systems (and possibly others) running NIS+, users should run keylogin(1) manually after login because opielogin(1) does not do that automatically like the system login(1) program. There are reports that some versions of GNU C Compiler (GCC) (when installed on some systems) use their own termios(4) instead of the system's termios(4). This can cause problems. If you are having compilation problems that seem to relate to termios and you are using GCC, you should probably verify that it is using the system's termios(4) and not some internal-to-GCC termios(4). One report indicates that Sun's C compiler works fine with SunOS 4.1.3/4.1.4 on SPARC, but that some version of GCC on the same system has this termios(4) problem. We haven't reproduced these problems ourselves and hence aren't sure what is happening, but we pass this along for your information. (This may have something to do with the use of GNU libc) If a user has a valid entry in the opiekeys database but has an asterisk in their traditional password entry, they will not be able to log in via opielogin, but opielogin will decrement their sequence number if a valid response is received. On some systems, the OPIE login program does not always display a "login:" prompt the first time. There is a race condition in many older telnetds that is probably the cause of this problem. This should be fixed by replacing your telnetd with the latest version of the stock telnetd (ftp.cray.com:/src/telnet). The standard HPUX compiler is severely drain bamaged. One of the worst parts is that it sometimes won't grok a symbol definition with forward slashes in them properly and can choke badly on the definition of the key file's location. If this happens to you, install and use GCC. (This problem may or may not also come up with the optional HP ANSI C compiler -- we don't know for sure what compilers have this problem). As of OPIE 2.2, the seed is converted to lower case and its length is checked in order to comply with the OTP specification. If any of your users have seeds that use capital letters or are too long, they need to run the OPIE 2.2 opiepasswd program to re-initialize their sequence to one with a different seed. opielogin is a replacement for /bin/login. It is NOT an OPIE "shell." You can use it as one, but don't be surprised if it doesn't behave the way you expect -- we've seen various reports of success and failure when used this way. An OPIE "shell" is on the TODO list. Clients that use opiegen() will automatically send a re-initialization extended response if the sequence number falls below ten. If the server does not support this, the user will need to log in using opiekey and reset his sequence manually (using opiepasswd). For reasons that remain very unclear, Solaris passes the login name from getty/telnetd to login by stuffing it in the terminal input buffer instead of passing it on the command line like every other *IX. This is just plain broken. Solaris has other problems with its telnetd and getty; you may want to consider getting the telnet(d) sources (ftp.cray.com:/src/telnet) and reasonable getty sources (try sunsite.unc.edu:/pub/Linux/system/Serial, at least one of agetty, mingetty, and getty_ps should work) and replacing the Solaris versions with these. OPIE should work *much* more happily with these programs than the ones that come with Solaris. However, there could be negative side effects -- this is not a procedure recommended for the faint of heart. OPIE is a lot more fussy than it used to be about lock files and where it puts them. The lock file directory must be a directory used only for OPIE lock files. It must be a directory, owned by the superuser, and must be mode 0700. opieauto is a potential security hole. It opens a limited window of exposure by transmitting and storing information that can be used to generate one or more OTPs earlier than the current sequence number. Every effort has been made to limit the potential for compromise to the user- specified window. However, an attacker with superuser priveleges or access to your account on the client system can still generate OTPs based on the information cached via opieauto. In practice, there are other ways for such an an attacker to get your entire secret pass phrase, so this is probably not creating a significant new security problem. However, because of this potential for problems and because opieauto uses system features that are not present on all systems, opieauto support is not compiled in by default and must be specifically enabled at compile time. Many users are running OPIE with the key file on a shared NFS volume in order to use OTP as a single-login system for a cluster of machines. OPIE was NOT designed to be operated this way, though it does seem to work. If it fails or if this proves insecure, this is not OPIE's fault. Note that, if you do this, you probably want to share the OPIE lock files too. Gripes ====== Is it too much to ask that certain OS vendors just do the right thing and not "fix" what isn't broken? (Look at all the ifdefs in the OPIE code and the answer is clear) utmp and wtmp handling in OPIE has been a very, very sore subject. Every vendor does things differently, and, of course, most of them swear they are complying to some or other "standard." My (cmetz) conclusion is that the only thing that is standard about utmp and wtmp handling is that it will be nonstandard on any given system. I've tried a lot of things and I've wasted *a lot* of time on trying to make utmp and wtmp handling work for everybody; my conclusion is that it will never happen. While I am still interested in hearing about fixes for utmp/wtmp on systems where they don't work, I'm not likely to go out of my way to fix utmp/wtmp handling. If you want it fixed, the best way to do it is to fix it yourself and contribute a patch. As long as the patch is reasonable, it will be included in the next release. If you can't wait, use the --disable-utmp option. Credits ======= First and foremost credit goes to Phil Karn, Neil M. Haller, and John S. Walden of Bellcore for creating the S/Key Version 1 software distribution and for making its source code freely available to the public. Without their work, OPIE would not exist. Neil has also invested a good amount of his time in the development of a standard for One-Time Passwords so that packages like OPIE can interoperate. The first NRL OPIE distribution included modifications made primarily by Dan McDonald of the U.S. Naval Research Laboratory (NRL) during March 1994. The 2nd NRL OPIE distribution, which has a number of improvements in areas such as portability of software and ease of installation, is primarily the work of Ran Atkinson and Craig Metz. Other NRL contributors include Brian Adamson, Steve Batsell, Preston Mullen, Bao Phan, Jim Ramsey, and Georg Thomas. Some of version 2.2 was developed at NRL and released as a work in progress. Most of the release version was developed by Craig Metz (also of NRL), others at The Inner Net, and contributors from the Internet community. Versions beyond 2.2 were developed outside NRL, so don't blame them if they don't work (But please credit them when it does. Without the NRL effort, there wouldn't be an OPIE). We would like to also thank everyone who helped us by by beta testing, reporting bugs, suggesting improvements, and/or sending us patches. We appreciate your contributions -- they have helped to make OPIE more of a community effort. These contributors include: Mowgli Assor Lawrie Brown Andrew Davis Taso N. Devetzis Carson Gaspar Dennis Glatting Ben Golding Axel Grewe "Hobbit" Kojima Hajime Darren Hosking Matt Hucke Kenji Kamizono Charles Karney Jeff Kletsky Peter Koch Martijn Koster Osamu Kurati Ayamura Kikuchi Ronald van der Meer Bret Musser Hiroshi Nakano Ikuo Nakagawa Angelo Neri C. R. Oldham Ossama Othman D. Jason Penney John Perkins Steve Price Jim Simmons Steve Simmons Brad Smith Werner Wiethege Ken-ichi Yamasaki Wietse Venema OPIE development at NRL was sponsored by the Information Security Program Office (PD 71E), U.S. Space and Naval Warfare Systems Command, Crystal City, Virginia. If you have problems with OPIE, please follow the instructions under "If OPIE Doesn't Work." Under NO circumstances should you send trouble reports directly to the authors or contributors. They WILL BE IGNORED. Trademarks ========== S/Key is a trademark of Bell Communications Research (Bellcore). UNIX is a trademark of X/Open. NRL is a trademark of the U. S. Naval Research Laboratory. All other trademarks are trademarks of their respective owners. The term "OPIE" is in the public domain and hence cannot be legally trademarked by anyone. Please do not abuse it. Copyrights ========== %%% portions-copyright-cmetz-96 Portions of this software are Copyright 1996-1999 by Craig Metz, All Rights Reserved. The Inner Net License Version 2 applies to these portions of the software. You should have received a copy of the license with this software. If you didn't get a copy, you may request one from <firstname.lastname@example.org>. Portions of this software are Copyright 1995 by Randall Atkinson and Dan McDonald, All Rights Reserved. All Rights under this copyright are assigned to the U.S. Naval Research Laboratory (NRL). The NRL Copyright Notice and License Agreement applies to this software. Portions of this software are copyright 1980-1990 Regents of the University of California, all rights reserved. The Berkeley Software License Agreement specifies the terms and conditions for redistribution. Portions of this software are copyright 1990 Bell Communications Research (Bellcore), all rights reserved.