mdw@git.distorted.org.uk Git - secnet/blob - README

   1 secnet - flexible VPN software
   2
   3 * Introduction
   4
   5 secnet allows large virtual private networks to be constructed
   6 spanning multiple separate sites.  It is designed for the case where a
   7 private network connecting many hosts is 'hidden' behind a single
   8 globally-routable IP address, but can also be applied in other
   9 circumstances.  It communicates entirely using UDP, and works well
  10 with gateways that implement network address translation.
  11
  12 If you are installing secnet to join an existing VPN, you should read
  13 the 'INSTALL' file and your particular VPN's documentation now.  You
  14 may need to refer back to this file for information on the netlink and
  15 comm sections of the configuration file.
  16
  17 If you are thinking about setting up a new VPN of any size (from one
  18 providing complete links between multiple sites to a simple
  19 laptop-to-host link), read the section in this file on 'Creating a
  20 VPN'.
  21
  22 * Creating a VPN
  23
  24 XXX TODO
  25
  26 * secnet configuration file format
  27
  28 By default secnet on linux reads /etc/secnet/secnet.conf.  The default
  29 may be different on other platforms.
  30
  31 This file defines a dictionary (a mapping from keys to values) full of
  32 configuration information for secnet.  Two keys must be defined in
  33 this file for secnet to start.  One is "system", a dictionary
  34 containing systemwide control parameters.  The other is "sites", a
  35 list of all the sites that you intend to communicate with.
  36
  37 The configuration file has a very simple syntax; keys are defined as
  38 follows:
  39
  40 key definition;
  41 or
  42 key = definition;
  43
  44 (the "=" is optional)
  45
  46 Keys must match the following regular expression:
  47 [[:alpha:]_][[:alnum:]\-_]*
  48
  49 i.e. the first character must be an alpha or an underscore, and the
  50 remaining characters may be alphanumeric, '-' or '_'.
  51
  52 Keys can be defined to be a comma-separated list of any of the
  53 following types:
  54
  55   a boolean
  56   a string, in quotes
  57   a number, in decimal
  58   a dictionary of definitions, enclosed in { }
  59   a "closure", followed by arguments
  60   a path to a key that already exists, to reference that definition
  61
  62 Note that dictionaries can be nested: a key in one dictionary can
  63 refer to another dictionary. When secnet looks for a key in a
  64 particular directory and can't find it, it looks in the dictionary's
  65 lexical 'parents' in turn until it finds it (or fails to find it at
  66 all and stops with an error).
  67
  68 Definitions can refer to previous definitions by naming them with a
  69 path.  Paths are key1/key2/key3... (starting from wherever we find
  70 key1, i.e. in the current dictionary or any of its parents), or
  71 alternatively /key1/key2/key3... (to start from the root).
  72 Definitions cannot refer to future definitions.
  73
  74 Example:
  75
  76 a=1;
  77 b=2;
  78 c={ d=3; e=a; };
  79 f={ a=4; g=c; };
  80
  81 The following paths are valid:
  82 a is 1
  83 b is 2
  84 c is a dictionary:
  85  c/d is 3
  86  c/e is 1
  87 f is a dictionary:
  88  f/a is 4
  89  f/g is a dictionary:
  90   f/g/d is 3
  91   f/g/e is 1
  92
  93 Note that f/g/e is NOT 4.
  94
  95 In a future version of secnet it will also be permissible to list
  96 other dictionaries before a dictionary definition,
  97 eg. <defaults,otherdefaults>{definitions}.  These will be searched in
  98 order for keys, before the lexical parent.  (This is not yet
  99 implemented)
 100
 101 Elements that are lists are inserted into lists in definitions, not
 102 referenced by them (i.e. you can't have lists of lists).
 103
 104 Some closures may be followed by an argument list in ( ), and may
 105 return any number of whatever type they like (including other
 106 closures).  Some types of closure (typically those returned from
 107 invokations of other closures) cannot be invoked.
 108
 109 closure { definitions } is short for closure({definitions}).
 110
 111 The main body of secnet, and all the additional modules, predefine
 112 some keys in the root dictionary.  The main ones are:
 113
 114   yes, true, True, TRUE:   the boolean value True
 115   no, false, False, FALSE: the boolean value False
 116   makelist:   turns a dictionary (arg1) into a list of definitions
 117               (ignoring the keys)
 118   readfile:   reads a file (arg1) and returns it as a string
 119
 120 Keys defined by modules are described below, in the module
 121 documentation.
 122
 123 Other configuration files can be included inline by writing "include
 124 filename" at the start of a line.
 125
 126 After the configuration file is read, secnet looks for particular keys
 127 in configuration space to tell it what to do:
 128
 129  system: a dictionary which can contain the following keys:
 130    log (log closure): a destination for system messages
 131    userid (string): the userid for secnet to run as once it drops privileges
 132    pidfile (string): where to store its PID
 133
 134  sites: a list of closures of type 'site', which define other tunnel
 135         endpoints that secnet will attempt to communicate with
 136
 137 * secnet command line options
 138
 139 XXX TODO
 140
 141 * secnet builtin modules
 142
 143 ** resolver
 144
 145 Defines:
 146   adns (closure => resolver closure)
 147
 148 adns: dict argument
 149   config (string): optional, a resolv.conf for ADNS to use
 150
 151 ** random
 152
 153 Defines:
 154   randomsrc (closure => randomsrc closure)
 155
 156 randomsrc: string[,bool]
 157   arg1: filename of random source
 158   arg2: if True then source is blocking
 159
 160 ** udp
 161
 162 Defines:
 163   udp (closure => comm closure)
 164
 165 udp: dict argument
 166   port (integer): UDP port to listen and send on
 167   buffer (buffer closure): buffer for incoming packets
 168   authbind (string): optional, path to authbind-helper program
 169
 170 ** util
 171
 172 Defines:
 173   logfile (closure => log closure)
 174   syslog (closure => log closure)
 175   sysbuffer (closure => buffer closure)
 176
 177 logfile: dict argument
 178   filename (string): where to log to
 179   class (string list): what type of messages to log
 180     { "debug-config", M_DEBUG_CONFIG },
 181     { "debug-phase", M_DEBUG_PHASE },
 182     { "debug", M_DEBUG },
 183     { "all-debug", M_DEBUG|M_DEBUG_PHASE|M_DEBUG_CONFIG },
 184     { "info", M_INFO },
 185     { "notice", M_NOTICE },
 186     { "warning", M_WARNING },
 187     { "error", M_ERROR },
 188     { "security", M_SECURITY },
 189     { "fatal", M_FATAL },
 190     { "default", M_WARNING|M_ERROR|M_SECURITY|M_FATAL },
 191     { "verbose", M_INFO|M_NOTICE|M_WARNING|M_ERROR|M_SECURITY|M_FATAL },
 192     { "quiet", M_FATAL }
 193
 194 syslog: dict argument
 195   ident (string): include this string in every log message
 196   facility (string): facility to log as
 197     { "authpriv", LOG_AUTHPRIV },
 198     { "cron", LOG_CRON },
 199     { "daemon", LOG_DAEMON },
 200     { "kern", LOG_KERN },
 201     { "local0", LOG_LOCAL0 },
 202     { "local1", LOG_LOCAL1 },
 203     { "local2", LOG_LOCAL2 },
 204     { "local3", LOG_LOCAL3 },
 205     { "local4", LOG_LOCAL4 },
 206     { "local5", LOG_LOCAL5 },
 207     { "local6", LOG_LOCAL6 },
 208     { "local7", LOG_LOCAL7 },
 209     { "lpr", LOG_LPR },
 210     { "mail", LOG_MAIL },
 211     { "news", LOG_NEWS },
 212     { "syslog", LOG_SYSLOG },
 213     { "user", LOG_USER },
 214     { "uucp", LOG_UUCP }
 215
 216 sysbuffer: integer[,dict]
 217   arg1: buffer length
 218   arg2: options:
 219     lockdown (boolean): if True, mlock() the buffer
 220
 221 ** site
 222
 223 Defines:
 224   site (closure => site closure)
 225
 226 site: dict argument
 227   local-name (string): this site's name for itself
 228   name (string): the name of the site's peer
 229   netlink (netlink closure)
 230   comm (comm closure)
 231   resolver (resolver closure)
 232   random (randomsrc closure)
 233   local-key (rsaprivkey closure)
 234   address (string): optional, DNS name used to find our peer
 235   port (integer): mandatory if 'address' is specified: the port used
 236     to contact our peer
 237   networks (string list): networks that our peer may claim traffic for
 238   key (rsapubkey closure): our peer's public key
 239   transform (transform closure): how to mangle packets sent between sites
 240   dh (dh closure)
 241   hash (hash closure)
 242   key-lifetime (integer): max lifetime of a session key, in ms [one hour]
 243   setup-retries (integer): max number of times to transmit a key negotiation
 244     packet [5]
 245   setup-timeout (integer): time between retransmissions of key negotiation
 246     packets, in ms [1000]
 247   wait-time (integer): after failed key setup, wait this long (in ms) before
 248     allowing another attempt [20000]
 249   renegotiate-time (integer): if we see traffic on the link after this time
 250     then renegotiate another session key immediately [depends on key-lifetime]
 251   keepalive (bool): if True then attempt always to keep a valid session key
 252   log-events (string list): types of events to log for this site
 253     unexpected: unexpected key setup packets (may be late retransmissions)
 254     setup-init: start of attempt to setup a session key
 255     setup-timeout: failure of attempt to setup a session key, through timeout
 256     activate-key: activation of a new session key
 257     timeout-key: deletion of current session key through age
 258     security: anything potentially suspicious
 259     state-change: steps in the key setup protocol
 260     packet-drop: whenever we throw away an outgoing packet
 261     dump-packets: every key setup packet we see
 262     errors: failure of name resolution, internal errors
 263     all: everything (too much!)
 264   netlink-options (string list): options to pass to netlink device when
 265     registering remote networks
 266     soft: create 'soft' routes that go away when there's no key established
 267       with the peer
 268     allow-route: allow packets from our peer to be sent down other tunnels,
 269       as well as to the host
 270
 271 ** transform
 272
 273 Defines:
 274   serpent256-cbc (closure => transform closure)
 275
 276 ** netlink
 277
 278 Defines:
 279   null-netlink (closure => netlink closure)
 280
 281 null-netlink: dict argument
 282   name (string): name for netlink device, used in log messages
 283   networks (string list): networks on the host side of the netlink device
 284   exclude-remote-networks (string list): networks that may never be claimed
 285     by any remote site using this netlink device
 286   local-address (string): IP address of host's tunnel interface
 287   secnet-address (string): IP address of this netlink device
 288   mtu (integer): MTU of host's tunnel interface
 289
 290 ** slip
 291
 292 Defines:
 293   userv-ipif (closure => netlink closure)
 294
 295 userv-ipif: dict argument
 296   userv-path (string): optional, where to find userv ["userv"]
 297   service-user (string): optional, username for userv-ipif service ["root"]
 298   service-name (string): optional, name of userv-ipif service ["ipif"]
 299   buffer (buffer closure): buffer for assembly of host->secnet packets
 300  plus generic netlink options, as for 'null-netlink'
 301
 302 ** tun
 303
 304 Defines:
 305   tun (closure => netlink closure) [only on linux-2.4]
 306   tun-old (closure => netlink closure)
 307
 308 tun: dict argument
 309   device (string): optional, path of TUN/TAP device file ["/dev/net/tun"]
 310   interface (string): optional, name of tunnel network interface
 311   ifconfig-path (string): optional, path to ifconfig command
 312   route-path (string): optional, path to route command
 313   buffer (buffer closure): buffer for host->secnet packets
 314  plus generic netlink options, as for 'null-netlink'
 315
 316 tun-old: dict argument
 317   device (string): optional, path of TUN/TAP device file ["/dev/tun*"]
 318   interface (string): optional, name of tunnel network interface
 319   interface-search (bool): optional, whether to search for a free tunnel
 320     interface (True if 'device' not specified, otherwise False)
 321   ifconfig-path (string): optional, path to ifconfig command
 322   route-path (string): optional, path to route command
 323  plus generic netlink options, as for 'null-netlink'
 324
 325 ** rsa
 326
 327 Defines:
 328   rsa-private (closure => rsaprivkey closure)
 329   rsa-public (closure => rsapubkey closure)
 330
 331 rsa-private: string[,bool]
 332   arg1: filename of SSH private key file (version 1, no password)
 333   arg2: whether to check that the key is usable [default True]
 334
 335 rsa-public: string,string
 336   arg1: encryption key (decimal)
 337   arg2: modulus (decimal)
 338
 339 ** dh
 340
 341 Defines:
 342   diffie-hellman (closure => dh closure)
 343
 344 diffie-hellman: string,string[,bool]
 345   arg1: modulus (hex)
 346   arg2: generator (hex)
 347   arg3: whether to check that the modulus is prime [default True]
 348
 349 ** md5
 350
 351 Defines:
 352   md5 (hash closure)
 353
 354 ** sha1
 355
 356 Defines:
 357   sha1 (hash closure)