1 secnet - flexible VPN software
5 secnet is Copyright (C) 1995--2003 Stephen Early <steve@greenend.org.uk>
6 It is distributed under the terms of the GNU General Public License,
7 version 2 or later. See the file COPYING for more information.
9 The IP address handling library in ipaddr.py is Copyright (C)
10 1996--2000 Cendio Systems AB, and is distributed under the terms of
15 secnet allows large virtual private networks to be constructed
16 spanning multiple separate sites. It is designed for the case where a
17 private network connecting many hosts is 'hidden' behind a single
18 globally-routable IP address, but can also be applied in other
19 circumstances. It communicates entirely using UDP, and works well
20 with gateways that implement network address translation.
22 If you are installing secnet to join an existing VPN, you should read
23 the 'INSTALL' file and your particular VPN's documentation now. You
24 may need to refer back to this file for information on the netlink and
25 comm sections of the configuration file.
27 If you are thinking about setting up a new VPN of any size (from one
28 providing complete links between multiple sites to a simple
29 laptop-to-host link), read the section in this file on 'Creating a
32 * Mailing lists and bug reporting
34 There are two mailing lists associated with secnet: an 'announce' list
35 and a 'discuss' list. Their addresses are:
36 http://www.chiark.greenend.org.uk/mailman/listinfo/secnet-announce
37 http://www.chiark.greenend.org.uk/mailman/listinfo/secnet-discuss
39 The -announce list receives one message per secnet release. The
40 -discuss list is for general discussion, including help with
41 configuration, bug reports, feature requests, etc.
43 Bug reports should be sent to <steve@greenend.org.uk>; they will be
44 forwarded to the -discuss list by me.
50 * secnet configuration file format
52 By default secnet on linux reads /etc/secnet/secnet.conf. The default
53 may be different on other platforms.
55 This file defines a dictionary (a mapping from keys to values) full of
56 configuration information for secnet. Two keys must be defined in
57 this file for secnet to start. One is "system", a dictionary
58 containing systemwide control parameters. The other is "sites", a
59 list of all the sites that you intend to communicate with.
61 The configuration file has a very simple syntax; keys are defined as
70 Keys must match the following regular expression:
71 [[:alpha:]_][[:alnum:]\-_]*
73 i.e. the first character must be an alpha or an underscore, and the
74 remaining characters may be alphanumeric, '-' or '_'.
76 Keys can be defined to be a comma-separated list of any of the
82 a dictionary of definitions, enclosed in { }
83 a "closure", followed by arguments
84 a path to a key that already exists, to reference that definition
86 Note that dictionaries can be nested: a key in one dictionary can
87 refer to another dictionary. When secnet looks for a key in a
88 particular directory and can't find it, it looks in the dictionary's
89 lexical 'parents' in turn until it finds it (or fails to find it at
90 all and stops with an error).
92 Definitions can refer to previous definitions by naming them with a
93 path. Paths are key1/key2/key3... (starting from wherever we find
94 key1, i.e. in the current dictionary or any of its parents), or
95 alternatively /key1/key2/key3... (to start from the root).
96 Definitions cannot refer to future definitions.
105 The following paths are valid:
117 Note that f/g/e is NOT 4.
119 Elements that are lists are inserted into lists in definitions, not
120 referenced by them (i.e. you can't have lists of lists).
122 Some closures may be followed by an argument list in ( ), and may
123 return any number of whatever type they like (including other
124 closures). Some types of closure (typically those returned from
125 invokations of other closures) cannot be invoked.
127 closure { definitions } is short for closure({definitions}).
129 The main body of secnet, and all the additional modules, predefine
130 some keys in the root dictionary. The main ones are:
132 yes, true, True, TRUE, on: the boolean value True
133 no, false, False, FALSE, off: the boolean value False
134 makelist: turns a dictionary (arg1) into a list of definitions
136 readfile: reads a file (arg1) and returns it as a string
137 map: applies the closure specified as arg1 to each of the
138 remaining elements in the list in turn. Returns a list
139 made up of the outputs of the closure.
141 Keys defined by modules are described below, in the module
144 Other configuration files can be included inline by writing "include
145 filename" at the start of a line.
147 After the configuration file is read, secnet looks for particular keys
148 in configuration space to tell it what to do:
150 system: a dictionary which can contain the following keys:
151 log (log closure): a destination for system messages
152 userid (string): the userid for secnet to run as once it drops privileges
153 pidfile (string): where to store its PID
155 sites: a list of closures of type 'site', which define other tunnel
156 endpoints that secnet will attempt to communicate with
158 * secnet command line options
160 Usage: secnet [OPTION]...
162 -f, --silent, --quiet suppress error messages
163 -w, --nowarnings suppress warnings
164 -v, --verbose output extra diagnostics
165 -c, --config=filename specify a configuration file
166 -j, --just-check-config stop after reading configfile
167 -n, --nodetach do not run in background
168 -d, --debug=item,... set debug options
169 --help display this help and exit
170 --version output version information and exit
172 * secnet builtin modules
177 adns (closure => resolver closure)
180 config (string): optional, a resolv.conf for ADNS to use
185 randomsrc (closure => randomsrc closure)
187 randomsrc: string[,bool]
188 arg1: filename of random source
189 arg2: if True then source is blocking
194 udp (closure => comm closure)
197 address (string): IP address to listen and send on
198 port (integer): UDP port to listen and send on
199 buffer (buffer closure): buffer for incoming packets
200 authbind (string): optional, path to authbind-helper program
205 logfile (closure => log closure)
206 syslog (closure => log closure)
208 logfile: dict argument
209 filename (string): where to log to
210 class (string list): what type of messages to log
211 { "debug-config", M_DEBUG_CONFIG },
212 { "debug-phase", M_DEBUG_PHASE },
213 { "debug", M_DEBUG },
214 { "all-debug", M_DEBUG|M_DEBUG_PHASE|M_DEBUG_CONFIG },
216 { "notice", M_NOTICE },
217 { "warning", M_WARNING },
218 { "error", M_ERROR },
219 { "security", M_SECURITY },
220 { "fatal", M_FATAL },
221 { "default", M_WARNING|M_ERROR|M_SECURITY|M_FATAL },
222 { "verbose", M_INFO|M_NOTICE|M_WARNING|M_ERROR|M_SECURITY|M_FATAL },
225 logfile will close and reopen its file upon receipt of SIGHUP.
227 syslog: dict argument
228 ident (string): include this string in every log message
229 facility (string): facility to log as
230 { "authpriv", LOG_AUTHPRIV },
231 { "cron", LOG_CRON },
232 { "daemon", LOG_DAEMON },
233 { "kern", LOG_KERN },
234 { "local0", LOG_LOCAL0 },
235 { "local1", LOG_LOCAL1 },
236 { "local2", LOG_LOCAL2 },
237 { "local3", LOG_LOCAL3 },
238 { "local4", LOG_LOCAL4 },
239 { "local5", LOG_LOCAL5 },
240 { "local6", LOG_LOCAL6 },
241 { "local7", LOG_LOCAL7 },
243 { "mail", LOG_MAIL },
244 { "news", LOG_NEWS },
245 { "syslog", LOG_SYSLOG },
246 { "user", LOG_USER },
252 sysbuffer (closure => buffer closure)
254 sysbuffer: integer[,dict]
257 lockdown (boolean): if True, mlock() the buffer
262 site (closure => site closure)
265 local-name (string): this site's name for itself
266 name (string): the name of the site's peer
267 link (netlink closure)
268 comm (one or more comm closures): if there is more than one, the
269 first one will be used for any key setups initiated by us using the
270 configured address. Others are only used if our peer talks to
272 resolver (resolver closure)
273 random (randomsrc closure)
274 local-key (rsaprivkey closure)
275 address (string): optional, DNS name used to find our peer
276 port (integer): mandatory if 'address' is specified: the port used
278 key (rsapubkey closure): our peer's public key
279 transform (transform closure): how to mangle packets sent between sites
282 key-lifetime (integer): max lifetime of a session key, in ms
283 [one hour; mobile: 2 days]
284 setup-retries (integer): max number of times to transmit a key negotiation
285 packet [5; mobile: 30]
286 setup-timeout (integer): time between retransmissions of key negotiation
287 packets, in ms [2000; mobile: 1000]
288 wait-time (integer): after failed key setup, wait this long (in ms) before
289 allowing another attempt [20000; mobile: 10000]
290 renegotiate-time (integer): if we see traffic on the link after this time
291 then renegotiate another session key immediately (in ms)
292 [half key-lifetime, or key-lifetime minus 5 mins (mobile: 12 hours),
293 whichever is longer].
294 keepalive (bool): if True then attempt always to keep a valid session key.
295 Not actually currently implemented. [false]
296 log-events (string list): types of events to log for this site
297 unexpected: unexpected key setup packets (may be late retransmissions)
298 setup-init: start of attempt to setup a session key
299 setup-timeout: failure of attempt to setup a session key, through timeout
300 activate-key: activation of a new session key
301 timeout-key: deletion of current session key through age
302 security: anything potentially suspicious
303 state-change: steps in the key setup protocol
304 packet-drop: whenever we throw away an outgoing packet
305 dump-packets: every key setup packet we see
306 errors: failure of name resolution, internal errors
307 peer-addrs: changes to sets of peer addresses (interesting for mobile peers)
308 all: everything (too much!)
309 mobile (bool): if True then peer is "mobile" ie we assume it may
310 change its apparent IP address and port number without either it
311 or us being aware of the change; so, we remember the last several
312 port/addr pairs we've seen and send packets to all of them
313 (subject to a timeout). We maintain one set of addresses for key
314 setup exchanges, and another for data traffic. Two communicating
315 peers must not each regard the other as mobile, or all the traffic
316 in each direction will be triplicated (strictly, transmitted
317 mobile-peers-max times) and anyway two peers whose public contact
318 address may suddenly change couldn't communicate reliably because
319 their contact addresses might both change at once. [false]
320 mobile-peers-max (integer): Maximum number of peer port/addr pairs we
321 remember and send to. Must be at least 1 and no more than 5. [3]
322 mobile-peer-expiry (integer): For "mobile" peers only, the length
323 of time (in seconds) for which we will keep sending to multiple
324 address/ports from which we have not seen incoming traffic. [120]
325 local-mobile (bool): if True then other peers have been told we are
326 "mobile". This should be True iff the peers' site configurations
327 for us have "mobile True" (and if we find a site configuration for
328 ourselves in the config, we insist on this). The effect is to
329 check that there are no links both ends of which are allegedly
330 mobile (which is not supported, so those links are ignored) and
331 to change some of the tuning parameter defaults. [false]
333 Links involving mobile peers have some different tuning parameter
334 default values, which are generally more aggressive about retrying key
335 setup but more relaxed about using old keys. These are noted with
336 "mobile:", above, and apply whether the mobile peer is local or
342 eax-serpent (closure => transform closure)
347 serpent256-cbc (closure => transform closure)
352 null-netlink (closure => closure or netlink closure)
354 null-netlink: dict argument
355 name (string): name for netlink device, used in log messages
356 networks (string list): networks on the host side of the netlink device
357 remote-networks (string list): networks that may be claimed
358 by the remote site using this netlink device
359 local-address (string): IP address of host's tunnel interface
360 secnet-address (string): IP address of this netlink device
361 ptp-address (string): IP address of the other end of a point-to-point link
362 mtu (integer): MTU of host's tunnel interface
364 Only one of secnet-address or ptp-address may be specified. If
365 point-to-point mode is in use then the "routes" option must also be
366 specified, and netlink returns a netlink closure that should be used
367 directly with the "link" option to the site closure. If
368 point-to-point mode is not in use then netlink returns a closure that
369 may be invoked using a dict argument with the following keys to yield
371 routes (string list): networks reachable down the tunnel attached to
372 this instance of netlink
373 options (string list):
374 allow-route: allow packets coming from this tunnel to be routed to
375 other tunnels as well as the host (used for mobile devices like laptops)
376 soft: remove these routes from the host's routing table when
377 the tunnel link quality is zero
378 mtu (integer): default MTU over this link; may be updated by tunnel code
380 Netlink will dump its current routing table to the system/log on
386 userv-ipif (closure => netlink closure)
388 userv-ipif: dict argument
389 userv-path (string): optional, where to find userv ["userv"]
390 service-user (string): optional, username for userv-ipif service ["root"]
391 service-name (string): optional, name of userv-ipif service ["ipif"]
392 buffer (buffer closure): buffer for assembly of host->secnet packets
393 plus generic netlink options, as for 'null-netlink'
398 tun (closure => netlink closure) [only on linux-2.4]
399 tun-old (closure => netlink closure)
402 flavour (string): optional, type of TUN interface to use
403 ("guess","linux","bsd","streams")
404 device (string): optional, path of TUN/TAP device file ["/dev/net/tun"]
405 interface (string): optional, name of tunnel network interface
406 ifconfig-path (string): optional, path to ifconfig command
407 route-path (string): optional, path to route command
408 ifconfig-type (string): optional, how to perform ifconfig
409 route-type (string): optional, how to add and remove routes
410 types are: "guess", "ioctl", "bsd", "linux", "solaris-2.5"
411 buffer (buffer closure): buffer for host->secnet packets
412 plus generic netlink options, as for 'null-netlink'
414 I recommend you don't specify the 'interface' option unless you're
415 doing something that requires the interface name to be constant.
420 rsa-private (closure => rsaprivkey closure)
421 rsa-public (closure => rsapubkey closure)
423 rsa-private: string[,bool]
424 arg1: filename of SSH private key file (version 1, no password)
425 arg2: whether to check that the key is usable [default True]
427 rsa-public: string,string
428 arg1: encryption key (decimal)
429 arg2: modulus (decimal)
434 diffie-hellman (closure => dh closure)
436 diffie-hellman: string,string[,bool]
438 arg2: generator (hex)
439 arg3: whether to check that the modulus is prime [default True]
454 makelist (dictionary => list of definitions)
455 readfile (string => string)
456 map (closure,list => list)
459 returns a list consisting of the definitions in the dictionary. The keys
463 reads the named file and returns its contents as a string
466 applies the closure specified as arg1 to each of the elements in the list.
467 Returns a list made up of the outputs of the closure.