X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=README;h=e23701c9151dc4d946523914dbbf81b2a69251fa;hb=686e21aa2afbd14c3e59962f02a31c4dcd62e5d8;hp=731eaaa632258499ac854de62db7313b733c0b91;hpb=c4ccd63b1f4d8a556c4ad764a23364e4b7424338;p=secnet.git diff --git a/README b/README index 731eaaa..e23701c 100644 --- a/README +++ b/README @@ -1,75 +1,645 @@ -basE91 - converting binary data to ASCII text -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +secnet - flexible VPN software -Copyright (c) 2000-2006 Joachim Henke +* Copying +secnet is + Copyright 1995-2003 Stephen Early + Copyright 2002-2014 Ian Jackson + Copyright 1991 Massachusetts Institute of Technology + Copyright 1998 Ross Anderson, Eli Biham, Lars Knudsen + Copyright 1993 Colin Plumb + Copyright 1998 James H. Brown, Steve Reid + Copyright 2000 Vincent Rijmen, Antoon Bosselaers, Paulo Barreto + Copyright 2001 Saul Kravitz + Copyright 2004 Fabrice Bellard + Copyright 2002 Guido Draheim + Copyright 2005-2010 Free Software Foundation, Inc. + Copyright 1995-2001 Jonathan Amery + Copyright 1995-2003 Peter Benie + Copyright 2011 Richard Kettlewell + Copyright 2012 Matthew Vernon + Copyright 2013-2019 Mark Wooding + Copyright 1995-2013 Simon Tatham -basE91 is an advanced method for encoding binary data as ASCII characters. It -is similar to UUencode or base64, but is more efficient. The overhead produced -by basE91 depends on the input data. It amounts at most to 23% (versus 33% for -base64) and can range down to 14%, which typically occurs on 0-byte blocks. -This makes basE91 very useful for transferring larger files over binary -insecure connections like e-mail or terminal lines. +secnet is distributed under the terms of the GNU General Public +License, version 3 or later. Some individual files have more +permissive licences; where this is the case, it is documented in the +header comment for the files in question. -The current algorithm has been written with portability and simplicity in mind -an is therefore not necessarily optimised for speed. +secnet is distributed in the hope that it will be useful, but WITHOUT +ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or +FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +for more details. +The file COPYING contains a copy of the GNU GPL v3. -* Alphabet -As the name suggests, basE91 needs 91 characters to represent the encoded -binary data in ASCII. From the 94 printable ASCII characters (0x21-0x7E), the -following three ones have been omitted to build the basE91 alphabet: +* Introduction -- (dash, 0x2D) -' (apostrophe, 0x27) -\ (backslash, 0x5C) +secnet allows large virtual private networks to be constructed +spanning multiple separate sites. It is designed for the case where a +private network connecting many hosts is 'hidden' behind a single +globally-routable IP address, but can also be applied in other +circumstances. It communicates entirely using UDP, and works well +with gateways that implement network address translation. -The translation table is composed of the remaining characters as shown below. +If you are installing secnet to join an existing VPN, you should read +the 'INSTALL' file and your particular VPN's documentation now. You +may need to refer back to this file for information on the netlink and +comm sections of the configuration file. - 0 A 13 N 26 a 39 n 52 0 65 % 78 > - 1 B 14 O 27 b 40 o 53 1 66 & 79 ? - 2 C 15 P 28 c 41 p 54 2 67 ( 80 @ - 3 D 16 Q 29 d 42 q 55 3 68 ) 81 [ - 4 E 17 R 30 e 43 r 56 4 69 * 82 ] - 5 F 18 S 31 f 44 s 57 5 70 + 83 ^ - 6 G 19 T 32 g 45 t 58 6 71 , 84 _ - 7 H 20 U 33 h 46 u 59 7 72 . 85 ` - 8 I 21 V 34 i 47 v 60 8 73 / 86 { - 9 J 22 W 35 j 48 w 61 9 74 : 87 | -10 K 23 X 36 k 49 x 62 ! 75 ; 88 } -11 L 24 Y 37 l 50 y 63 # 76 < 89 ~ -12 M 25 Z 38 m 51 z 64 $ 77 = 90 " +If you are thinking about setting up a new VPN of any size (from one +providing complete links between multiple sites to a simple +laptop-to-host link), read the section in this file on 'Creating a +VPN'. +* Mailing lists and bug reporting -* Building +There are two mailing lists associated with secnet: an 'announce' list +and a 'discuss' list. Their addresses are: +http://www.chiark.greenend.org.uk/mailman/listinfo/secnet-announce +http://www.chiark.greenend.org.uk/mailman/listinfo/secnet-discuss -1. `cd' to the directory containing the package's source code and type `make' - to compile the package +The -announce list receives one message per secnet release. The +-discuss list is for general discussion, including help with +configuration, bug reports, feature requests, etc. -2. optionally, type `make check' to run any self-tests that come with the - package +Bug reports should be sent to ; they will be +forwarded to the -discuss list by me. -3. type `make install' to install the program and documentation in `/usr/local' - (to specify another installation prefix than `/usr/local', type - `make prefix=PATH install' instead) +* Creating a VPN -4. you can remove the program binaries and object files from the source code - directory by typing `make clean' +XXX TODO +* secnet configuration file format -* Developer +By default secnet on linux reads /etc/secnet/secnet.conf. The default +may be different on other platforms. -Joachim Henke +This file defines a dictionary (a mapping from keys to values) full of +configuration information for secnet. Two keys must be defined in +this file for secnet to start. One is "system", a dictionary +containing systemwide control parameters. The other is "sites", a +list of all the sites that you intend to communicate with. +The configuration file has a very simple syntax; keys are defined as +follows: -* Copying +key definition; +or +key = definition; + +(the "=" is optional) + +Keys must match the following regular expression: +[[:alpha:]_][[:alnum:]\-_]* + +i.e. the first character must be an alpha or an underscore, and the +remaining characters may be alphanumeric, '-' or '_'. + +Keys can be defined to be a comma-separated list of any of the +following types: + + a boolean + a string, in quotes + a number, in decimal + a dictionary of definitions, enclosed in { } + a "closure", followed by arguments + a path to a key that already exists, to reference that definition + +Note that dictionaries can be nested: a key in one dictionary can +refer to another dictionary. When secnet looks for a key in a +particular directory and can't find it, it looks in the dictionary's +lexical 'parents' in turn until it finds it (or fails to find it at +all and stops with an error). + +Definitions can refer to previous definitions by naming them with a +path. Paths are key1/key2/key3... (starting from wherever we find +key1, i.e. in the current dictionary or any of its parents), or +alternatively /key1/key2/key3... (to start from the root). +Definitions cannot refer to future definitions. + +Example: + +a=1; +b=2; +c={ d=3; e=a; }; +f={ a=4; g=c; }; + +The following paths are valid: +a is 1 +b is 2 +c is a dictionary: + c/d is 3 + c/e is 1 +f is a dictionary: + f/a is 4 + f/g is a dictionary: + f/g/d is 3 + f/g/e is 1 + +Note that f/g/e is NOT 4. + +Elements that are lists are inserted into lists in definitions, not +referenced by them (i.e. you can't have lists of lists). + +Some closures may be followed by an argument list in ( ), and may +return any number of whatever type they like (including other +closures). Some types of closure (typically those returned from +invokations of other closures) cannot be invoked. + +closure { definitions } is short for closure({definitions}). + +The main body of secnet, and all the additional modules, predefine +some keys in the root dictionary. The main ones are: + + yes, true, True, TRUE, on: the boolean value True + no, false, False, FALSE, off: the boolean value False + makelist: turns a dictionary (arg1) into a list of definitions + (ignoring the keys) + readfile: reads a file (arg1) and returns it as a string + map: applies the closure specified as arg1 to each of the + remaining elements in the list in turn. Returns a list + made up of the outputs of the closure. + +Keys defined by modules are described below, in the module +documentation. + +Other configuration files can be included inline by writing "include +filename" at the start of a line. + +After the configuration file is read, secnet looks for particular keys +in configuration space to tell it what to do: + + system: a dictionary which can contain the following keys: + log (log closure): a destination for system messages + userid (string): the userid for secnet to run as once it drops privileges + pidfile (string): where to store its PID + + sites: a list of closures of type 'site', which define other tunnel + endpoints that secnet will attempt to communicate with + +* secnet command line options + +Usage: secnet [OPTION]... + + -f, --silent, --quiet suppress error messages + -w, --nowarnings suppress warnings + -v, --verbose output extra diagnostics + -c, --config=filename specify a configuration file + -j, --just-check-config stop after reading configfile + -n, --nodetach do not run in background + -d, --debug=item,... set debug options + --help display this help and exit + --version output version information and exit + +* base91s + +secnet defines a variant of the base91 encoding `basE91', from + http://base91.sourceforge.net/ + +base91s is the same as baseE91 except that: + - in the encoded charset, `"' is replaced with `-' + - spaces, newlines etc. and other characters outside the charset + are not permitted (although in some places they may be ignored, + this is not guaranteed). + +* secnet builtin modules + +** resolver + +Defines: + adns (closure => resolver closure) + +adns: dict argument + config (string): optional, a resolv.conf for ADNS to use + +** random + +Defines: + randomsrc (closure => randomsrc closure) + +randomsrc: string[,bool] + arg1: filename of random source + arg2: if True then source is blocking + +** udp + +Defines: + udp (closure => comm closure) + +udp: dict argument + address (string list): IPv6 or IPv4 addresses to listen and send on; + default is all local addresses + port (integer): UDP port to listen and send on; optional if you + don't need to have a stable address for your peers to talk to + (in which case your site ought probably to have `local-mobile true'). + buffer (buffer closure): buffer for incoming packets + authbind (string): optional, path to authbind-helper program + +** polypath + +Defines: + polypath (closure => comm closure) + +polypath: dict argument + port (integer): UDP port to listen and send on + buffer (buffer closure): buffer for incoming packets + authbind (string): optional, path to authbind-helper program + max-interfaces (number): optional, max number of different interfaces to + use (also, maximum steady-state amount of packet multiplication); + interfaces marked with `@' do not count. + interfaces (string list): which interfaces to process; each entry is + optionally `!' or `+' or `@' followed by a glob pattern (which is + applied to a prospective interface using fnmatch with no flags). + `+' or nothing means to process normally. `!' means to ignore; + `@' means to use only in conjunction with dedicated-interface-addr. + If no list is specified, or the list ends with a `!' entry, a + default list is used/appended: + "!tun*","!tap*","!sl*","!userv*","!lo","@hippo*","*". + Patterns which do not start with `*' or an alphanumeric need to be + preceded by `!' or `+' or `@'. + monitor-command (string list): Program to use to monitor appearance + and disappearance of addresses on local network interfaces. Should + produce lines of the form `+|- 4|6 ' where is + an address literal. Each - line should relate to a previously + printed + line. On startup, should produce a + line for each + currently existing address. secnet does filtering so there is no + need to strip out tun interfaces, multicast addresses, and so on. + The command is run as the user secnet is started as (not the one + which secnet may drop privilege to due to the configured `userid'). + The default depends on the operating system. + permit-loopback (boolean): Normally, loopback IPv6 and IPv4 + addresses on local interfaces are disregarded, because such + interfaces are not interesting for communicating with distant + hosts. Setting this option will ignore that check, which can be + useful for testing. Setting this option also removes "!lo*" from + the default interface pattern list. + +When using this comm, packets are sent out of every active interface +on the host (where possible). It is important that interfaces created +by secnet itself are not included! secnet's default filter list tries +to do this. + +This comm only makes sense for sites which are mobile. That is, the +site closures used with this comm should all have the `local-mobile' +parameter set to `true'. When the local site site is not marked +mobile the address selection machinery might fixate on an unsuitable +address. + +polypath takes site-specific informtion as passed to the `comm-info' +site closure parameter. The entries understood in the dictionary +are: + dedicated-interface-addr (string): IPv4 or IPv6 address + literal. Interfaces specified with `@' in `interfaces' will be + used for the corresponding site iff the interface local address + is this address. + +For an interface to work with polypath, it must either have a suitable +default route, or be a point-to-point interface. In the general case +this might mean that the host would have to have multiple default +routes. However in practice the most useful configuration is two +interfaces being (1) wifi (2) mobile internet. + +I have had success on Linux by using network-manager for wifi and +invoking ppp directly for mobile internet. ppp sets up a +point-to-point link, and does not add a default route if there already +is one. network-manager always sets up a default route. The result +is that the wifi always has a default route (so is useable); ppp +(being a point-to-point link) does not need one. + +The use of polypath requires that secnet be started with root +privilege, to make the setsockopt(,,SO_BINDTODEVICE,) calls. If the +configuration specifies that secnet should drop privilege (see +`userid' above), secnet will keep a special process around for this +purpose; that process will handle local network interface changes but +does not deal with any packets, key exchange, etc. + +polypath support is only available when secnet is built against an +IPv6-capable version of adns (because it wants features in the newer +adns). + +** log + +Defines: + logfile (closure => log closure) + syslog (closure => log closure) + +logfile: dict argument + filename (string): where to log to; default is stderr + prefix (string): added to messages [""] + class (string list): what type of messages to log + { "debug-config", M_DEBUG_CONFIG }, + { "debug-phase", M_DEBUG_PHASE }, + { "debug", M_DEBUG }, + { "all-debug", M_DEBUG|M_DEBUG_PHASE|M_DEBUG_CONFIG }, + { "info", M_INFO }, + { "notice", M_NOTICE }, + { "warning", M_WARNING }, + { "error", M_ERROR }, + { "security", M_SECURITY }, + { "fatal", M_FATAL }, + { "default", M_WARNING|M_ERROR|M_SECURITY|M_FATAL }, + { "verbose", M_INFO|M_NOTICE|M_WARNING|M_ERROR|M_SECURITY|M_FATAL }, + { "quiet", M_FATAL } + +logfile will close and reopen its file upon receipt of SIGHUP. + +syslog: dict argument + ident (string): include this string in every log message + facility (string): facility to log as + { "authpriv", LOG_AUTHPRIV }, + { "cron", LOG_CRON }, + { "daemon", LOG_DAEMON }, + { "kern", LOG_KERN }, + { "local0", LOG_LOCAL0 }, + { "local1", LOG_LOCAL1 }, + { "local2", LOG_LOCAL2 }, + { "local3", LOG_LOCAL3 }, + { "local4", LOG_LOCAL4 }, + { "local5", LOG_LOCAL5 }, + { "local6", LOG_LOCAL6 }, + { "local7", LOG_LOCAL7 }, + { "lpr", LOG_LPR }, + { "mail", LOG_MAIL }, + { "news", LOG_NEWS }, + { "syslog", LOG_SYSLOG }, + { "user", LOG_USER }, + { "uucp", LOG_UUCP } + +** util + +Defines: + sysbuffer (closure => buffer closure) + +sysbuffer: integer[,dict] + arg1: buffer length + arg2: options: + lockdown (boolean): if True, mlock() the buffer + +** site + +Defines: + site (closure => site closure) + +site: dict argument + local-name (string): this site's name for itself + name (string): the name of the site's peer + link (netlink closure) + comm (one or more comm closures): if there is more than one, the + first one will be used for any key setups initiated by us using the + configured address. Others are only used if our peer talks to + them. + resolver (resolver closure) + random (randomsrc closure) + key-cache (privcache closure) + local-key (sigprivkey closure): Deprecated; use key-cache instead. + address (string list): optional, DNS name(s) used to find our peer; + address literals are supported too if enclosed in `[' `]'. + port (integer): mandatory if 'address' is specified: the port used + to contact our peer + peer-keys (string): path (prefix) for peer public key set file(s); + see README.make-secnet-sites re `pub' etc. and NOTES.peer-keys. + key (sigpubkey closure): our peer's public key (obsolete) + transform (transform closure): how to mangle packets sent between sites + dh (dh closure) + hash (hash closure): used for keys whose algorithm (or public + or private key file) does not imply the hash function + key-lifetime (integer): max lifetime of a session key, in ms + [one hour; mobile: 2 days] + setup-retries (integer): max number of times to transmit a key negotiation + packet [5; mobile: 30] + setup-timeout (integer): time between retransmissions of key negotiation + packets, in ms [2000; mobile: 1000] + wait-time (integer): after failed key setup, wait roughly this long + (in ms) before allowing another attempt [20000; mobile: 10000] + Actual wait time is randomly chosen between ~0.5x and ~1.5x this. + renegotiate-time (integer): if we see traffic on the link after this time + then renegotiate another session key immediately (in ms) + [half key-lifetime, or key-lifetime minus 5 mins (mobile: 12 hours), + whichever is longer]. + keepalive (bool): if True then attempt always to keep a valid session key. + [false] + log-events (string list): types of events to log for this site + unexpected: unexpected key setup packets (may be late retransmissions) + setup-init: start of attempt to setup a session key + setup-timeout: failure of attempt to setup a session key, through timeout + activate-key: activation of a new session key + timeout-key: deletion of current session key through age + security: anything potentially suspicious + state-change: steps in the key setup protocol + packet-drop: whenever we throw away an outgoing packet + dump-packets: every key setup packet we see + errors: failure of name resolution, internal errors + peer-addrs: changes to sets of peer addresses (interesting for mobile peers) + all: everything (too much!) + mobile (bool): if True then peer is "mobile" ie we assume it may + change its apparent IP address and port number without either it + or us being aware of the change; so, we remember the last several + port/addr pairs we've seen and send packets to all of them + (subject to a timeout). We maintain one set of addresses for key + setup exchanges, and another for data traffic. Two communicating + peers must not each regard the other as mobile, or all the traffic + in each direction will be triplicated (strictly, transmitted + mobile-peers-max times) and anyway two peers whose public contact + address may suddenly change couldn't communicate reliably because + their contact addresses might both change at once. [false] + mobile-peers-max (integer): Maximum number of peer port/addr pairs we + remember and send to. Must be at least 1 and no more than 5. + [4 if any address is configured, otherwise 3] + static-peers-max (integer): Maximum number of peer port/addr pairs + we can try for a static site. Must be at least 1 and no more + than 5. [4 or 3, as above] + mobile-peer-expiry (integer): For "mobile" peers only, the length + of time (in seconds) for which we will keep sending to multiple + address/ports from which we have not seen incoming traffic. [120] + local-mobile (bool): if True then other peers have been told we are + "mobile". This should be True iff the peers' site configurations + for us have "mobile True" (and if we find a site configuration for + ourselves in the config, we insist on this). The effect is to + check that there are no links both ends of which are allegedly + mobile (which is not supported, so those links are ignored) and + to change some of the tuning parameter defaults. [false] + mtu-target (integer): Desired value of the inter-site MTU for this + peering. This value will be advertised to the peer (which ought + to affect incoming packets), and if the peer advertises an MTU its + value will be combined with this setting to compute the inter-site + MTU. (secnet will still accept packets which exceed the + (negotiated or assumed) inter-site MTU.) Setting a lower + inter-site MTU can be used to try to restrict the sizes of the + packets sent over the underlying public network (e.g. to work + around network braindamage). It is not normally useful to set a + larger value for mtu-target than the VPN's general MTU (which + should be reflected in the local private interface MTU, ie the mtu + parameter to netlink). If this parameter is not set, or is set + to 0, the default is to use the local private link mtu. + comm-info (dict): Information for the comm, used when this site + wants to transmit. If the comm does not support this, it is + ignored. + +Links involving mobile peers have some different tuning parameter +default values, which are generally more aggressive about retrying key +setup but more relaxed about using old keys. These are noted with +"mobile:", above, and apply whether the mobile peer is local or +remote. + +** transform-eax + +Defines: + eax-serpent (closure => transform closure) + +** transform-cbcmac + +Defines: + serpent256-cbc (closure => transform closure) + +** netlink + +Defines: + null-netlink (closure => closure or netlink closure) + +null-netlink: dict argument + name (string): name for netlink device, used in log messages + networks (string list): networks on the host side of the netlink device + remote-networks (string list): networks that may be claimed + by the remote site using this netlink device + local-address (string): IP address of host's tunnel interface + secnet-address (string): IP address of this netlink device + ptp-address (string): IP address of the other end of a point-to-point link + mtu (integer): MTU of host's tunnel interface + +Only one of secnet-address or ptp-address may be specified. If +point-to-point mode is in use then the "routes" option must also be +specified, and netlink returns a netlink closure that should be used +directly with the "link" option to the site closure. If +point-to-point mode is not in use then netlink returns a closure that +may be invoked using a dict argument with the following keys to yield +a netlink closure: + routes (string list): networks reachable down the tunnel attached to + this instance of netlink + options (string list): + allow-route: allow packets coming from this tunnel to be routed to + other tunnels as well as the host (used for mobile devices like laptops) + soft: remove these routes from the host's routing table when + the tunnel link quality is zero + mtu (integer): MTU of host's tunnel interface + +Netlink will dump its current routing table to the system/log on +receipt of SIGUSR1. + +** slip + +Defines: + userv-ipif (closure => netlink closure) + +userv-ipif: dict argument + userv-path (string): optional, where to find userv ["userv"] + service-user (string): optional, username for userv-ipif service ["root"] + service-name (string): optional, name of userv-ipif service ["ipif"] + buffer (buffer closure): buffer for assembly of host->secnet packets + plus generic netlink options, as for 'null-netlink' + +** tun + +Defines: + tun (closure => netlink closure) [only on linux-2.4] + tun-old (closure => netlink closure) + +tun: dict argument + flavour (string): optional, type of TUN interface to use + ("guess","linux","bsd","streams") + device (string): optional, path of TUN/TAP device file ["/dev/net/tun"] + interface (string): optional, name of tunnel network interface + ifconfig-path (string): optional, path to ifconfig command + route-path (string): optional, path to route command + ifconfig-type (string): optional, how to perform ifconfig + route-type (string): optional, how to add and remove routes + types are: "guess", "ioctl", "bsd", "linux", "solaris-2.5" + buffer (buffer closure): buffer for host->secnet packets + plus generic netlink options, as for 'null-netlink' + +I recommend you don't specify the 'interface' option unless you're +doing something that requires the interface name to be constant. + +** privcache + +Cache of dynamically loaded private keys. + +Defines: + priv-cache (closure => privcache closure) + +priv-cache: dict argument + privkeys (string): path prefix for private keys. Each key is + looked for at this path prefix followed by the 10-character + hex key id. + privcache-size (integer): optional, maximum number of private + keys to retain at once. [5] + privkey-max (integer): optional, maximum size of private key + file in bytes. [4095] + +** pubkeys + +Defines: + make-public (closure => sigpubkey closure) + +make-public: ( + arg1: sigscheme name + arg2: base91s encoded public key data, according to algorithm + +** rsa + +Defines: + sigscheme algorithm 00 "rsa1" + rsa-private (closure => sigprivkey closure) + rsa-public (closure => sigpubkey closure) + +rsa1 sigscheme algorithm: + private key: SSH private key file, version 1, no password + public key: SSH public key file, version 1 + (length, restrictions, email, etc., ignored) + +rsa-private: string[,bool] + arg1: filename of SSH private key file (version 1, no password) + arg2: whether to check that the key is usable [default True] + +rsa-public: string,string + arg1: encryption key (decimal) + arg2: modulus (decimal) + +** dh + +Defines: + diffie-hellman (closure => dh closure) + +diffie-hellman: string,string[,bool] + arg1: modulus (hex) + arg2: generator (hex) + arg3: whether to check that the modulus is prime [default True] + +** md5 + +Defines: + md5 (hash closure) + +** sha1 + +Defines: + sha1 (hash closure) + +** conffile -All source code in this package is released under the terms of the BSD license. -See the file LICENSE for copying permission. +Defines: + makelist (dictionary => list of definitions) + readfile (string => string) + map (closure,list => list) +makelist: dictionary + returns a list consisting of the definitions in the dictionary. The keys + are discarded. -* See also +readfile: string + reads the named file and returns its contents as a string -Please visit the basE91 home page [http://base91.sourceforge.net/] for the -latest version and pre-compiled binaries. +map: + applies the closure specified as arg1 to each of the elements in the list. + Returns a list made up of the outputs of the closure.