$Id: README,v 1.50 2003/06/12 04:08:09 nickm Exp $ ====================================================================== This is Mixminion version 0.0.4. WARNING! Mixminion 0.0.4 breaks backward compatibility with version 0.0.3. Versions older than 0.0.3 are no longer supported; you should upgrade now. CONTENTS: I. Overview II. What's new in this version III. How to upgrade IV. How to install V. How to send messages VI. How to run a server VII. How to report bugs and suggestions VIII. Future interoperability IX. How to contribute I. OVERVIEW =========== Mixminion is the standard implementation of the Type III anonymous remailer protocol, which lets you send very anonymous email. This best-of-breed remailer uses conservative design approaches to provide security against most known attacks. We chose a simple, extensible design so that we can provide a robust core system and then experiment with new research features such as dummy policies, directory servers, and reputation systems. You can find the latest information at http://mixminion.net/, or on the mailing list, archived at http://archives.seul.org/mixminion/dev/. Please consider subscribing, especially if you're going to run a node. This is a testing alpha release. You will probably only want to use it if you are technically inclined, curious, and interested in helping the Mixminion development effort. WARNING! Do NOT use this release if you require strong anonymity. It has known deficiencies, including some that make it possible for an adversary to trace your message through the system. II. WHAT'S NEW IN THIS VERSION? =============================== NEW IN FINAL 0.0.4 release: BUGFIXES: - Fixed a bug that would sometimes give a useless error message when trying to build a message with a too-long path. NEW IN VERSION 0.0.4rc4: BUGFIXES: - Improved error message on nonexistent directory. - Fixed a bug (found by Mike Gurski) that could kill a server if a message was received for an old key in between deleting the old key's replay cache, and deleting the old key itself. - Fixed a bug in setting up server directories. NEW IN VERSION 0.0.4rc3: BUGFIXES: - Memory leaks: - Made server code release memory more aggressively. - Fixed a race condition where messages could be queued on a server connection that was already shutting down. - Fixed memory leaks on certificate checking. - Server bugs: - Fixed a server crash on key-rotation that would occur when to trying to open the same hash log db file twice. - Fixed bug that would crash server if PublicKeyLifetime changed. - Made server differentiate between ENOENT and EACCES when starting. - Fixed a bug that would cause key generation to happen at the wrong times. - Other bugs: - Fixed a bug related to using client keyrings without passwords. - Made ASCII armor more reliable in the face of extraneous space, headerless armor, and so on. - Excluded superceeded servers from directories more thoroughly. OTHER CHANGES: - Cosmetic: - Commented most uncommented code. - Refactored path selection again. - Refactored code to use more reliable file accessing functions. - Added more unit tests - Performance enhancements: - Changed recommended OpenSSL version to 0.9.7b. - Implementation quality - Improved a few log messages. - Made included etc/mixminiond.conf more reasonable by using a less aggressive retry schedule, commenting out unused Allow lines, and decreasing PublicKeyLifetime. - Made os.expanduser work on more configuration values. - Enabled threading on more C functions. NEW IN VERSION 0.0.4rc2: BUGFIXES: - The server shouldn't crash so much when it gets bad TLS errors or timed-out connections. Sometimes, it will give better errors when it does. NEW IN VERSION 0.0.4rc1: First steps toward directory automation: - Servers generate new keys and server descriptors when the old ones are close to expiring. (~2 weeks) - Servers also regenerate server descriptors when their configuration changes. - When a set of keys expires, a server rotates to the next set automatically (with some overlap). - Servers can upload their descriptors to a directory server automatically. - There's a trivial directory backend that accepts signed updates automatically, and queues new servers. - Directories now include a list of which servers are believed to be working correctly. Right now, this list is still manually configured. - There's a cron job that regenerates the directory every so often. Packet format overhaul: - Server RSA keys are now 2048 bits long. - The header representation is more compact now, so we don't pay in space for the increased key length. MMTP improvements: - The certificate regime has changed so that key rotation is now possible: instead of authenticating servers based on their TLS keys, we authenticate based on their identity keys, which never change. - Packets sent from a server to itself no longer hit the network. - When relaying messages, a server never opens more than 1 connection at a time to the same server. - MMTP clients now recognize a 'REJECTED' reply that a server can use to refuse messages when under high load. Other server improvements: - Servers can (optionally) track the number of packets received, relayed successfully, dropped, and so on. - Servers can recognize and advertise whether they are configured 'securely.' - The deliver/retry logic has been largely rewritten. It should freak out and die less frequently now. In any case, it also prints better debugging messages, and thrashes the disk less. Minor changes: - We now use real OpenPGP-style ASCII-armor. Accept no substitutes! Numerous UI Improvements: - There are saner error messages for many common cases. - Support for multiple SURB keys to prevent identity-blending attack. - There's a new (temporary) 'mixminion ping' command that you can use to tell whether a server is accepting connections. It's potentially dangerous (if you go pinging all the servers in your path), and has a banner saying so. - The path selection syntax has changed to be more flexible. (You can now specify a single random hop, or N random hops.) STILL NOT IN THIS VERSION: - We could use some man pages. - IP-based restrictions don't work. - No support for distributed directories. - Other stuff too numerous to mention; see TODO. III. HOW TO UPGRADE FROM MIXMINION 0.0.3 ======================================== First, follow the installation instructions from section IV to install the new version of the software. If you're running a server, you will need to upgrade your server's files. Follow these steps: 1. Your configuration file may be out of date. The following options are new (but not required): "Publish" "LogStats" "StatsInterval" "StatsFile" The following options have been renamed: "PublicKeySloppiness" -> "PublicKeyOverlap". The following options, formerly optional, are now mandatory: "Nickname" Because key rotation is now implemented, you may want to decrease the value you've chosen for PublicKeyLifetime. Formerly, "3 months" was typical. Now, something on the order of one to three weeks is probably in order. See etc/mixminiond.conf for an example. 2. Run 'mixminion server-upgrade' to delete keys and packets in obsolete formats. (If you forget this step, the server will remind you when you try to start it.) 3. Start your server as usual ('mixminion server-start') and try sending some messages through it. (You can find the filename(s) of the currently live server descriptors stored in $HOMEDIR/current-desc.) Example: % mixminion server-start [wait for server to start] % cat $HOMEDIR/current-desc $HOMEDIR/keys/key_0022/ServerDesc % cp `cat $HOMEDIR/current-desc` myserver % mixminion send -t -P './myserver,?,?' [Type your message, followed by Ctrl-D.] [Wait a while, and see if your message gets sent.] 4. When you're confident your server is working correctly, and you want to advertise your server to the rest of the world, edit your mixminiond.conf, and set the "Publish" option to 'yes'. 5. Restart your server. It will now advertise itself to the (still, alas!) central directory. The first time you do this, I have to update the directory manually (to prevent pseudospoofing). Once your server is listed, future updates will be get into the directory automatically. IV. HOW TO INSTALL MIXMINION ============================ The quick version. ------------------ % cd Mixminion-0.0.4 % make download-openssl % make build-openssl % make % make test EITHER: % su Password: # make install OR: % make install PREFIX=~ The verbose version. -------------------- 1) You must have Python version 2.0 or later installed on your system. The binary may be called "python", "python2", "python2.X", or something else. If you don't have Python >=v2.0, go install it. You can find source and binary distributions at http://www.python.org/. 2) If you have OpenSSL version 0.9.7beta3 or later, go to step 5. Otherwise, continue. 3) Run "make download-openssl". 4) Run "make build-openssl". If this step fails, OpenSSL didn't build correctly on your system. Go read contrib/openssl/INSTALL, and make OpenSSL build. 5) Run "make". If you don't get any error messages, go to step 6. If you have OpenSSL 0.9.7 installed, but the build script doesn't find it, you can force it to look in a particular location (say, "/home/ssl") with: make OPENSSL_PREFIX=/home/ssl This will make the scripts look for headers in $OPENSSL_PREFIX/include and libraries in $OPENSSL_PREFIX/lib. If the scripts *still* can't find OpenSSL 0.9.7, you can override the compile and link options directly, like this: make OPENSSL_CFLAGS='-I/home/ssl/include' \ OPENSSL_LDFLAGS='-L/home/ssl/libraries -lssl097 -lcrypto097' If your C compiler knows where to find OpenSSL on its own, but the build script doesn't trust it, you can disable searching like this: make SKIP_OPENSSL_SEARCH=y If you get any other errors, please report them to . 6) Run "make test" to run Mixminion's unit tests. If you get any errors, please report them to . 7) Run "make install" to install Mixminion. You may need to be root to execute this command. By default, Mixminion will install itself relative to your python distribution. If you want to install somewhere else (e.g. /home/miniond/), run "make install PREFIX=/home/miniond". A script called "mixminion" will be created in the 'bin' directory relative to your prefix, or in the same directory as the python executable if no prefix is provided. To make sure that everything was installed correctly, you can run "mixminion unittests". V. HOW TO SEND MESSAGES VIA MIXMINION ===================================== Just run one of the following command lines: mixminion send -t -i OR mixminion send -t (to read from stdin) OR mixminion send -t -i - (also reads from stdin) Mixminion will then take the following steps: A) Download and validate the latest server directory. (But only if you haven't done so since midnight GMT.) B) Select a path that ends at a server with SMTP support. (Currently, this defaults to 4 hops.) C) Read your message. D) Construct a Type III Mix packet containing your message. (For more information, see the links at http://www.mixminion.net/) E) Send the message to the first server in your path. To see a list of currently known servers, type: mixminion list-servers To force a reload of the server directory, type: mixminion send -t
[-i ] -D yes To send a message _without_ reloading the directory, type: mixminion send -t
[-i ] -D no To reload the directory without sending a message, type: mixminion send -D yes OR mixminion update-servers To see whether a server is running, type: mixminion ping (WARNING: This command is potentially dangerous, for a number of subtle and not-so-subtle reasons. It will go away before mixminion 1.0.) To force a path of a given length, type: mixminion send -t
[-i ] -H You can change the default by editing ~/.mixminionrc To specify a path manually, type: mixminion send -t
[-i ] -P The argument must be a comma separated list of either: (a) Server nicknames as given by 'list-servers' (b) Paths to files containing server descriptors [more info below] For example, to send a message through the servers Foo, Bar, Baz, and Quux, you would type "-P Foo,Bar,Baz,Quux." To specify a randomly chosen server, you can include a question mark, like this: -P 'Foo,?,Bar,?' [Foo, a random server, Bar, and another random server] You can specify a sequence of N random servers like this: -P 'Foo,*3,Bar' [Foo, three random servers, then Bar.] If you have specified a path length (explicitly or in ~/.mixminionrc) you can use a '*' to indicate as many random servers as are needed to make your path long enough: -P 'Foo,*' [Path that starts with Foo] -P '*,Foo' [Path that ends with Foo] -P 'Foo,Bar,*,Quux' [Path that starts with Foo and Bar, and ends with Quux] {ADVANCED} By default, the swap point will be halfway through the path (rounding up). To specify a swap point explicitly, use a colon in your path, as in: -P 'Foo,Bar:Baz,Quux' [Swap headers at server Bar] --swap-at= [Swap headers at the n'th server] If you don't know what a swap point is, don't worry. :) If you want to use the same path by default for all of your messages, edit the ~/.mixminonrc and change the ForwardPath line: # By default, use the same servers for entry and exit each time, # with three randomly chosen servers in the middle. ForwardPath: FavoriteEntry,?,?,?,FavoriteExit To send a dummy message, specify "drop" instead of an email address, as in: mixminion send -t drop mixminion send -t drop -P '*,Foo' mixminion send -t drop -H 8 To queue a message for later transmission, run "mixminion queue" instead of "mixminion send": mixminion queue -t
-i -P To see all the packets waiting in the queue: mixminion inspect-queue To attempt to deliver all messages waiting in the queue: mixminion flush To attempt to deliver no more than 16 messages: mixminion flush -n 16 (QUEUE NOTE: By default, when "mixminion send" fails to deliver a message, it leaves that message in the queue to be reattempted later. To suppress this behavior, use the "--no-queue" option: mixminion send --no-queue -t
-i -P Also, as a final sidenote, "mixminion send --queue" is a synonym for "mixminion queue".) To decode a message you have received, type: mixminion decode -i -o . Or, to send output to stdout: mixminion decode -i (When you receive a message with non-printing characters via email, it will be encoded in base64 before delivery. When you receive a reply, its contents will be encrypted. The "mixminion decode" command extracts the original text from either kind of message as best it can.) To generate a reply block, type: mixminion generate-surb -t To send the reply block to a file, instead of to stdout: mixminion generate-surb -t -o If you specify a "SURBAddress" field in ~/.mixminionrc, you may omit the target address: mixminion generate-surb Also, you can control path selection in the same way as with sending messages: mixminion generate-surb -H 3 (a 3-hop path) mixminion generate-surb -P '*,Foo' (end with server foo) mixminion generate-surb -P 'Bar,*' (start with server bar) You can use the '-n' option to generate many reply blocks at once: mixminion generate-surb -n 100 (generate 100 reply blocks) To save space, you can specify binary (as opposed to text) encoding for your reply blocks: mixminion generate-surb -b -o By default, the client will choose servers to make sure that your reply blocks will still function for 7 days. To choose a different lifetime: mixminion generate-surb --lifetime=1 (1 day) Note that if you choose an overlong lifetime, there may not be enough servers whose keys will be valid for the entire period. If you maintain multiple pseudonymous identities, to avoid a SURB-swapping attack, you should use the --identity option so that you can later see which messages were to sent to which SURB identity. mixminion generate-surb --identity=alice -o alices_surb mixminion generate-surb --identity=bob -o bobs_surb Once you have a reply block for a user, you can send reply messages by typing: mixminion send -R -i The other options to 'send' and 'pool' still apply; the reply block takes the place of the destination address: mixminion send -R (Read from stdin) mixminion send -R -D yes (Reload directory) mixminion send -R -H 4 (Use 4 hops before reply.) mixminion send -R -P 'Z,*' (Start with server "Z".) mixminion pool -R (Pool the message.) IMPORTANT: Mixminion reply blocks can only be used once! (Thus, SURB="Single Use Reply Block".) The program will remember which reply blocks it has used in the past, but if you give a single reply block to 2 users, it will only work for one of them, once. As a convenience, if you have a file containing many reply blocks, you can use it with '-R': the client will choose the first reply block from the file which has not expired, and which you have not yet used. To inspect the reply blocks in a file, you can run: mixminion inspect-surbs If you need to use a proxy server to use the web you can specify it using the http_proxy environment variable: export http_proxy=http://proxy:3128/ mixminion send -D yes VI. HOW TO RUN YOUR OWN MIXMINION SERVER ======================================== 1) Create a copy of the "etc/mixminiond.conf" file from the mixminion distribution and place it where you like. Mixminion will automatically look in ~/.mixminiond.conf, ~/etc/mixminiond.conf, and /etc/mixminiond.conf. However, you can store it anywhere. 2) Edit mixminiond.conf to reflect your own system settings. 3) Run your server for the first time: "mixminion server-start -f " (The -f flag and path are only necessary if you placed the configuration file somehwere other than ~/.mixminiond.conf, ~/etc/mixminiond.conf, or /etc/mixminiond.conf.) 5) To try out your server, clients will need a copy of your server descriptor, whose location is stored $SERVER_HOME/current-desc. For example, if your mixminiond.conf contains the following line: Homedir: /home/mixminion/spool Then if you read the contents of /home/mixminion/spool/current-desc, you will find a filename like: "/home/mixminion/spool/keys/key_0001/ServerDesc". This file is your current server descriptor. Mixminion supports a global directory of server descriptors. Until you are listed in that directory, clients can import your ServerDesc file (if they have a copy) by hand by running: mixminion import-server They can also use your ServerDesc without importing it by using the filename as a part of their path: mixminion send -t
-P ',?,?' 6) When you're ready to advertise your server, edit 'mixminiond.conf' and set the 'Publish' option to 'yes'. When you restart your server, it will advertise itself to the central directory. The first time you do this, I have to update the directory manually (to prevent pseudospoofing). Once your server is listed, future updates will be get into the directory automatically. WARNING: We don't have statistics yet, so the system isn't robust in the presence of unreliable servers in the directory. Please don't publish a server if you don't think you can keep it up for a good while. {This step will be more automated in later versions.} To shut down a server: mixminion server-stop [-f configfile] To make a server reload its configuration: mixminion server-reload [-f configfile] (Right now, this just closes and re-opens the log files.) Your server can be configured to keep track of the number of packets it receives and other interesting statistics. Ordinarily, it aggregates these totals and flushes a report to disk at a configurable interval. If you want to see statistics in the _current_ interval, run: mixminion server-stats [-f configfile] VII. HOW TO REPORT BUGS AND SUGGEST NEW FEATURES ================================================ To report bugs, please use the Bugzilla pages at http://bugs.noreply.org. For other correspondence, please email . For help in debugging, please try to send a copy of: * What command you were running * The complete error you got, including stack trace (if any) If your error occurred on a running server, please make a copy of your log--it might be helpful. VIII. FUTURE INTEROPERABILITY ============================= Mixminion is not yet feature complete. As the software moves closer to official release, backwards-incompatible changes *WILL* be introduced. Future versions of Mixminion, including future versions in the 0.x track, may reject messages from older versions as additional security features are added. Furthermore, the present preview versions include necessary diagnostic features that potentially compromise anonymity and would be inappropriate in a production system; these features will be removed or disabled by 1.0. IX. HOW TO CONTRIBUTE ===================== Send patches to . If you can, please submit unified diffs against the latest version of the code in CVS. Make sure to run 'make test' before you send in any patches, so you can see whether your patch broke existing code. (It's okay if you're not sure how to fix the test, but please let me know when you send your patch.) ------------------ (for emacs) Local Variables: mode:text indent-tabs-mode:nil fill-column:77 End: