447 lines
20 KiB
Plaintext
447 lines
20 KiB
Plaintext
OPIE Software Distribution, Release 2.31 Important Information
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======================================== =====================
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Introduction
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============
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"One-time Passwords In Everything" (OPIE) is a freely distributable
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software package originally developed at and for the US Naval Research
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Laboratory (NRL). Recent versions are the result of a cooperative effort
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between of NRL, several of the original NRL authors, The Inner Net, and many
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other contributors from the Internet community.
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OPIE is an implementation of the One-Time Password (OTP) System that
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is being considered for the Internet standards-track. OPIE provides a one-time
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password system. The system should be secure against the passive attacks
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now commonplace on the Internet (see RFC 1704 for more details). The system
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is vulnerable to active dictionary attacks, though these are not widespread
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at present and can be detected through proper use of system audit
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software.
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OPIE is primarily written for UNIX-like operating systems, but
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we are working to make applicable portions portable to other operating systems.
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The OPIE software is derived in part from and is fully interoperable with the
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Bell Communications Research (Bellcore) S/Key Release 1 software. Because
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Bellcore claims "S/Key" as a trademark for their software, NRL was forced to
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use a different name (we picked "OPIE") for this software distribution.
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OPIE includes the following additions/modifications to the
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original Bellcore S/Key(tm) Version 1 software:
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* Just about three command installation (unpack the software, run the
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configure script, and run make install). While we still recommend that you
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follow instructions and test things by hand, the more adventurous can
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install OPIE quickly.
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* A modified BSD FTP daemon that does OTP.
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* A version of su that uses OTP by default.
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* MD5 support. MD5 is now the default algorithm, though MD4 is still supported
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by changing a parameter in the Makefile. This change was made because MD5 is
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widely believed to be cryptographically stronger than MD4 (see RFC 1321).
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* A more portable version of MD4 has been substituted for the original MD4.
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This should solve the endian problems that were in S/Key.
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* Most of the system-dependencies have been moved to a new file "opie_cfg.h".
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* Configuration options have been moved to the Makefile.
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* Isolated system dependencies (e.g. BSDisms) with appropriate #ifdefs.
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* Revised the opiekey(1) program to simultaneously support MD4 and MD5, with
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the default algorithm being tunable using the MDX symbol in the Makefile.
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* More operating systems are supported by recent versions of OPIE, but older
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BSD systems that aren't close to being compliant with the POSIX standard are
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no longer supported.
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* Transition mechanisms are optional to prevent potential back doors.
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* On systems using the /etc/opieaccess transition mechanism, users can choose
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to require the use of OPIE to login to their accounts when it would
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otherwise be optional.
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* Bug fixes
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* Cosmetic changes
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* Prompts (optionally) identify specifically what kind of entry (system
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password, secret pass phrase, or OTP response) is allowed.
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* Changes to mostly conform with the draft Internet OTP standard.
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A Glance at What's New
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======================
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2.31 March 20, 1997.
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Removed active attack protection support due to patent problems.
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Moved user locks to a separate directory.
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Moved user-serviceable configuration options to the configure script.
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Lots of portability and bug fixes.
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2.3 September 22, 1996
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Autoconf is now the only supported configuration method.
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Lots of internal functions got re-written in ways that will make some
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planned future changes easier.
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OTP extended responses, such as automatic re-initialization.
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Support for a supplemental key file that stores information that was
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not in the original /etc/skeykeys file. This allows OPIE to store extra data
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needed for things like the OTP re-initialization extended response without
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breaking interoperability with other S/Key derived programs. This file is
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named "/etc/opiekeys.ext" by default. Unlike the standard key file, it MUST
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NOT be world readable.
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OPIE should better support some of the native "features" of drain
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bamaged OSs such as AIX, HP-UX, and Solaris.
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OPIE's utmp/wtmp handling has been completely re-written. This should
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solve many of the utmp/wtmp problems people have been having.
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Lots of cleanups.
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Bug fixes.
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2.22 May 3, 1996.
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More minor bug fixes. OPIE once again works on Solaris 2.x.
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2.21 April 27, 1996.
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Minor bug fixes.
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2.2 April 11, 1996.
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opiesubr.c, opiesubr2.c, and a few other functions moved into
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a subdirectory and split into files with fine granularity. Ditto with
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missing function replacements. This subdirectory structure changes a lot
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of things around and more splitting like this should be expected in the
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near future.
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Added opiegenerator() library function that should make it very easy
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to create OTP clients using the OPIE library (this function is subject to
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change: there are a few problems remaining to be solved). Just about re-write
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opiegetpass() to use raw I/O and got most of the OPIE programs actually using
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that function. Autoconf build fixes. Lots of bug fixes. Lots of portability
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fixes. Function declarations should be ANSI style for ANSI compilers. Several
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fixes to bring OPIE in line with the latest OTP spec. MJR DES key crunch
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de-implemented.
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Added sample programs: opiegen (client) and opieserv (server).
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Probably broke non-autoconf support along the way :(. I've tried to
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bring this back in sync, but it may still be broken.
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2.11 December 27, 1995.
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Minor bug fixes.
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2.10 December 26, 1995.
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Optional autoconf support. opieinfo is now a normal program.
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Bugs fixed -- should work much better on SunOS, HP-UX, and AIX.
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System Requirements
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===================
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In order to build and run properly, OPIE requires:
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* A UNIX-like operating system
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* An ANSI C compiler and run-time library
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* POSIX.1- and X/Open XPG-compliance (including termios)
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* The BSD sockets API
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* Approximately five megabytes of free disk space
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In practice, we believe that many systems who are close to meeting
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these requirements but aren't completely there (for example, SunOS with the
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native compiler) will also work. Systems who aren't anywhere near close
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(for example, DOS) are not likely to work without major adjustments to the
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OPIE code.
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If OPIE Doesn't Work
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====================
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First and foremost, make sure you have the latest version of OPIE. The
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latest version is available by anonymous FTP at:
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ftp://ftp.nrl.navy.mil/pub/security/opie
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and
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ftp://ftp.inner.net/pub/opie
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If you have installed the OPIE software (either through "make test"
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in (7) above or "make install" in (14)), you can run "make uninstall" from the
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OPIE software distribution directory. This should remove the OPIE software and
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restore the original system programs, but it will not work properly (and can
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even result in the total loss of the old system programs -- beware!) if the
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installation procedure itself did not work properly.
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If you are running a release version, try installing the latest public
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test version (look around). These frequently have already fixed the problem
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you are seeing, but may have new problems of their own (that's why they're
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test versions!).
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OPIE is NOT supported software. We don't promise to support you or
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even to acknowledge your mail, but we are interested in bug reports and are
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reasonable folks. We also have an interest in seeing OPIE work on as many
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systems as we can. However, if your system doesn't meet the basic requirements
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for OPIE, this will probably require an unreasonable amount of effort.
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The best bug reports include a diagnosis of the problem and a fix.
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Your bug report can still be valuable if you can at least diagnose what the
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problem is. If you just tell us "it doesn't work," then we won't be able to
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do anything to help you.
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We've received a number of bug reports from people that look
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interesting, only to find when we try to follow up on them that the user
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either has an invalid return address or never bothered to respond to our
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followup. Please make sure that bug reports you send us have an electronic
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mail address that we can reply to somewhere in them (if necessary, just
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put it in the message body). If we send you a response and you are unable
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to invest the time to work with us to solve the problem, please tell us --
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few things are more irritating than when someone sends us information
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about a bug that we'd like to fix and then is never heard from again.
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We try to respond to all properly submitted bug reports. Improperly
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submitted bug reports will be responded to only if we have time left after
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responding to properly submitted bug reports. We deliberately ignore bug
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"reports" sent to mailing lists or USENET news groups instead of or before
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our bug report address. At the least, the latter practice is lacking in
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courtesy.
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The file BUG-REPORT contains our bug reporting form. Please use it
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and follow the submission instructions in that file. We are going to switch
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to machine-parsed bug report processing sometime in the near future to make
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it easier to coordinate bug hunting.
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Gotchas
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=======
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While an almost universal "feature", most people remain unaware that
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an intruder can log into a system, then log in again by running the "login"
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command from a shell. Because the second login is from the local host, the
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utmp entry will not show a remote login host anymore. The OPIE replacement
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for /bin/login currently carries on this behavior for compatibility reasons.
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If you would like to prevent this from happening, you should change the
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permissions of /bin/login to 0100, thus preventing unprivileged users from
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executing it. This fix should work on non-OPIE /bin/login programs as well.
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On 4.3BSDish systems, the supplied /bin/login replacement obtains
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the terminal type for the console comes from the console line in the /etc/ttys
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file. Several systems contain a default entry in this file that specifies the
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console terminal type as "unknown". This is probably not what you want.
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The OPIE FTP daemon responds with two 530 error messages if you have
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not yet logged in and execute a command that will also do a PORT request. This
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is a feature, not a bug, as the FTP client is really sending the server two
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commands (for instance, a PORT and a LIST if you tell your BSD FTP client to do
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a DIR command) and the server is responding to each of them with an error. The
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stock BSD FTP daemon doesn't check the PORT commands to see if you are logged
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in, so you would only get one error message. This change should not break any
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standards-compliant FTP client, but there are a number of brain-damaged GUI
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clients that have a track record for not dealing gracefully with any server
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other than the stock BSD one.
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The /etc/opieaccess transition mechanism is, by definition, a security
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hole in the OPIE software because an attacker could use it to circumvent the
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requirement for OPIE authentication. You should compile the software with
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support for this file disabled unless you absolutely cannot use the software
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without it because of your environment. If you do use this support for
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transition purposes, you should move people to OTP authentication as quickly
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as possible and rebuild and reinstall OPIE with this transition support
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disabled so that you won't have a lurking security hole.
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If this wasn't already clear, do not let your sequence number fall
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below about ten. If your sequence number reaches zero, your OTP sequence
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can only be reset by the superuser. System administrators should make this
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caveat known to their users.
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On Solaris 2.x systems (and possibly others) running NIS+, users
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should run keylogin(1) manually after login because opielogin(1) does not
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do that automatically like the system login(1) program.
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There are reports that some versions of GNU C Compiler (GCC)
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(when installed on some systems) use their own termios(4) instead of
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the system's termios(4). This can cause problems. If you are having
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compilation problems that seem to relate to termios and you are using
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GCC, you should probably verify that it is using the system's
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termios(4) and not some internal-to-GCC termios(4). One report
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indicates that Sun's C compiler works fine with SunOS 4.1.3/4.1.4 on
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SPARC, but that some version of GCC on the same system has this
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termios(4) problem. We haven't reproduced these problems ourselves
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and hence aren't sure what is happening, but we pass this along for
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your information. (This may have something to do with the use of GNU
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libc)
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If a user has a valid entry in the opiekeys database but has an
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asterisk in their traditional password entry, they will not be able to
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log in via opielogin, but opielogin will decrement their sequence number
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if a valid response is received.
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On some systems, the OPIE login program does not always display
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a "login:" prompt the first time. There is a race condition in many older
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telnetds that is probably the cause of this problem. This should be fixed by
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replacing your telnetd with the latest version of the stock telnetd
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(ftp.cray.com:/src/telnet).
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The standard HPUX compiler is severely drain bamaged. One of the
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worst parts is that it sometimes won't grok a symbol definition with forward
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slashes in them properly and can choke badly on the definition of the key
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file's location. If this happens to you, install and use GCC. (This problem
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may or may not also come up with the optional HP ANSI C compiler -- we don't
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know for sure what compilers have this problem).
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As of OPIE 2.2, the seed is converted to lower case and its length is
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checked in order to comply with the OTP specification. If any of your users
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have seeds that use capital letters or are too long, they need to run the OPIE
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2.2 opiepasswd program to re-initialize their sequence to one with a different
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seed.
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opielogin is a replacement for /bin/login. It is NOT an OPIE "shell."
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You can use it as one, but don't be surprised if it doesn't behave the way
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you expect -- we've seen various reports of success and failure when used this
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way. An OPIE "shell" is on the TODO list.
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Clients that use opiegen() will automatically send a re-initialization
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extended response if the sequence number falls below ten. If the server does
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not support this, the user will need to log in using opiekey and reset his
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sequence manually (using opiepasswd).
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For reasons that remain very unclear, Solaris passes the login name
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from getty/telnetd to login by stuffing it in the terminal input buffer
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instead of passing it on the command line like every other *IX. This is just
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plain broken. Solaris has other problems with its telnetd and getty; you may
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want to consider getting the telnet(d) sources (ftp.cray.com:/src/telnet)
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and reasonable getty sources (try sunsite.unc.edu:/pub/Linux/system/Serial, at
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least one of agetty, mingetty, and getty_ps should work) and replacing the
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Solaris versions with these. OPIE should work *much* more happily with these
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programs than the ones that come with Solaris. However, there could be negative
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side effects -- this is not a procedure recommended for the faint of heart. An
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even more drastic solution more likely to make OPIE happy is to install Linux
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or NetBSD on your box ;)
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OPIE is a lot more fussy than it used to be about lock files and where
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it puts them. The lock file directory must be a directory used only for OPIE
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lock files. It must be a directory, owned by the superuser, and must be mode
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0700.
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Gripes
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======
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Is it too much to ask that certain OS vendors just do the right thing
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and not "fix" what isn't broken? (Look at all the ifdefs in the OPIE code and
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the answer is clear)
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utmp and wtmp handling in OPIE has been a very, very sore subject.
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Every vendor does things differently, and, of course, most of them swear they
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are complying to some or other "standard." My (cmetz) conclusion is that the
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only thing that is standard about utmp and wtmp handling is that it will be
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nonstandard on any given system. I've tried a lot of things and I've wasted
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*a lot* of time on trying to make utmp and wtmp handling work for everybody;
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my conclusion is that it will never happen. I personally am willing to stand
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behind the code for utmp/wtmp handling on reasonable Linux and 4.4BSD-Lite
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systems. If it breaks, tell me and I will fix it. While I am still interested
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in hearing about fixes for other OSs, I'm not likely to go out of my way to fix
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utmp/wtmp handling on them. If you want it fixed, the best way to do it is to
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fix it yourself and give me a patch. As long as the patch is reasonable, I'll
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include it in the next release. If you can't wait, use the --disable-utmp
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option.
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Credits
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=======
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First and foremost credit goes to Phil Karn, Neil M. Haller, and John
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S. Walden of Bellcore for creating the S/Key Version 1 software distribution
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and for making its source code freely available to the public. Without their
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work, OPIE would not exist. Neil has also invested a good amount of his time
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in the development of a standard for One-Time Passwords so that packages like
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OPIE can interoperate.
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The first NRL OPIE distribution included modifications made primarily
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by Dan McDonald of the U.S. Naval Research Laboratory (NRL) during March 1994.
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The 2nd NRL OPIE distribution, which has a number of improvements in areas
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such as portability of software and ease of installation, is primarily the
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work of Ran Atkinson and Craig Metz. Other NRL contributors include Brian
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Adamson, Steve Batsell, Preston Mullen, Bao Phan, Jim Ramsey, and Georg Thomas.
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Some of version 2.2 was developed at NRL and released as a work in
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progress. Most of the release version was developed by Craig Metz (also of
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NRL), others at The Inner Net, and contributors from the Internet community.
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Versions beyond 2.2 were developed outside NRL, so don't blame them if they
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don't work (But please credit them when it does. Without the NRL effort, there
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wouldn't be an OPIE).
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We would like to also thank everyone who helped us by by beta testing,
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reporting bugs, suggesting improvements, and/or sending us patches. We
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appreciate your contributions -- they have helped to make OPIE more of a
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community effort. These contributors include:
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Mowgli Assor
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Lawrie Brown
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Andrew Davis
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Axel Grewe
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"Hobbit"
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Kojima Hajime
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Darren Hosking
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Martijn Koster
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Osamu Kurati
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Ayamura Kikuchi
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Hiroshi Nakano
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Ikuo Nakagawa
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Angelo Neri
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C. R. Oldham
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D. Jason Penney
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John Perkins
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Jim Simmons
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Brad Smith
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Werner Wiethege
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Wietse Venema
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OPIE development at NRL was sponsored by the Information Security
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Program Office (PD 71E), U.S. Space and Naval Warfare Systems Command, Crystal
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City, Virginia.
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If you have problems with OPIE, please follow the instructions under
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"If OPIE Doesn't Work." Under NO circumstances should you send trouble
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reports directly to the authors or contributors.
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Trademarks
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==========
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S/Key is a trademark of Bell Communications Research (Bellcore).
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UNIX is a trademark of X/Open.
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NRL is a trademark of the U. S. Naval Research Laboratory.
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All other trademarks are trademarks of their respective owners.
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The term "OPIE" is in the public domain and hence cannot be legally
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trademarked by anyone.
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Copyrights
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==========
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%%% portions-copyright-cmetz-96
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Portions of this software are Copyright 1996-1997 by Craig Metz, All Rights
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Reserved. The Inner Net License Version 2 applies to these portions of
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the software.
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You should have received a copy of the license with this software. If
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you didn't get a copy, you may request one from <license@inner.net>.
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Portions of this software are Copyright 1995 by Randall Atkinson and Dan
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McDonald, All Rights Reserved. All Rights under this copyright are assigned
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to the U.S. Naval Research Laboratory (NRL). The NRL Copyright Notice and
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License Agreement applies to this software.
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Portions of this software are copyright 1980-1990 Regents of the
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University of California, all rights reserved. The Berkeley Software
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License Agreement specifies the terms and conditions for redistribution.
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Portions of this software are copyright 1990 Bell Communications Research
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(Bellcore), all rights reserved.
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