1 secnet - flexible VPN software
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.
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.
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
26 * secnet configuration file format
28 By default secnet on linux reads /etc/secnet/secnet.conf. The default
29 may be different on other platforms.
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.
37 The configuration file has a very simple syntax; keys are defined as
46 Keys must match the following regular expression:
47 [[:alpha:]_][[:alnum:]\-_]*
49 i.e. the first character must be an alpha or an underscore, and the
50 remaining characters may be alphanumeric, '-' or '_'.
52 Keys can be defined to be a comma-separated list of any of the
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
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).
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.
81 The following paths are valid:
93 Note that f/g/e is NOT 4.
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
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).
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.
109 closure { definitions } is short for closure({definitions}).
111 The main body of secnet, and all the additional modules, predefine
112 some keys in the root dictionary. The main ones are:
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
118 readfile: reads a file (arg1) and returns it as a string
120 Keys defined by modules are described below, in the module
123 Other configuration files can be included inline by writing "include
124 filename" at the start of a line.
126 After the configuration file is read, secnet looks for particular keys
127 in configuration space to tell it what to do:
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
134 sites: a list of closures of type 'site', which define other tunnel
135 endpoints that secnet will attempt to communicate with
137 * secnet command line options
141 * secnet builtin modules
146 adns (closure => resolver closure)
151 randomsrc (closure => randomsrc closure)
156 udp (closure => comm closure)
161 logfile (closure => log closure)
162 sysbuffer (closure => buffer closure)
167 site (closure => site closure)
172 serpent256-cbc (closure => transform closure)
177 userv-ipif (closure => netlink closure)
178 tun (closure => netlink closure) [only on linux-2.4]
179 tun-old (closure => netlink closure)
180 null-netlink (closure => netlink closure)
185 rsa-private (closure => rsaprivkey closure)
186 rsa-public (closure => rsapubkey closure)
191 diffie-hellman (closure => dh closure)