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74eb47db | 1 | .\" -*-nroff-*- |
2 | .\". | |
fc916a09 MW |
3 | .\" Manual for the server |
4 | .\" | |
5 | .\" (c) 2008 Straylight/Edgeware | |
6 | .\" | |
7 | . | |
8 | .\"----- Licensing notice --------------------------------------------------- | |
9 | .\" | |
10 | .\" This file is part of Trivial IP Encryption (TrIPE). | |
11 | .\" | |
12 | .\" TrIPE is free software; you can redistribute it and/or modify | |
13 | .\" it under the terms of the GNU General Public License as published by | |
14 | .\" the Free Software Foundation; either version 2 of the License, or | |
15 | .\" (at your option) any later version. | |
16 | .\" | |
17 | .\" TrIPE is distributed in the hope that it will be useful, | |
18 | .\" but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | .\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | .\" GNU General Public License for more details. | |
21 | .\" | |
22 | .\" You should have received a copy of the GNU General Public License | |
23 | .\" along with TrIPE; if not, write to the Free Software Foundation, | |
24 | .\" Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
25 | . | |
26 | .\"-------------------------------------------------------------------------- | |
e99aedcf | 27 | .so ../common/defs.man \" @@@PRE@@@ |
fc916a09 MW |
28 | . |
29 | .\"-------------------------------------------------------------------------- | |
74eb47db | 30 | .TH tripe 8 "10 February 2001" "Straylight/Edgeware" "TrIPE: Trivial IP Encryption" |
fc916a09 MW |
31 | . |
32 | .\"-------------------------------------------------------------------------- | |
74eb47db | 33 | .SH "NAME" |
fc916a09 | 34 | . |
74eb47db | 35 | tripe \- a simple VPN daemon |
fc916a09 MW |
36 | . |
37 | .\"-------------------------------------------------------------------------- | |
74eb47db | 38 | .SH "SYNOPSIS" |
fc916a09 | 39 | . |
74eb47db | 40 | .B tripe |
46dde080 | 41 | .RB [ \-DF ] |
74eb47db | 42 | .RB [ \-d |
43 | .IR dir ] | |
d13e5724 | 44 | .RB [ \-b |
45 | .IR addr ] | |
33ced0d3 | 46 | .RB [ \-p |
47 | .IR port ] | |
42da2a58 | 48 | .RB [ \-n |
49 | .IR tunnel ] | |
d13e5724 | 50 | .br |
85b1ebd6 | 51 | \c |
33ced0d3 | 52 | .RB [ \-U |
53 | .IR user ] | |
54 | .RB [ \-G | |
55 | .IR group ] | |
d13e5724 | 56 | .RB [ \-a |
57 | .IR socket ] | |
58 | .RB [ \-T | |
59 | .IR trace-opts ] | |
74eb47db | 60 | .br |
85b1ebd6 | 61 | \c |
74eb47db | 62 | .RB [ \-k |
63 | .IR priv-keyring ] | |
64 | .RB [ \-K | |
65 | .IR pub-keyring ] | |
66 | .RB [ \-t | |
67 | .IR key-tag ] | |
fc916a09 MW |
68 | . |
69 | .\"-------------------------------------------------------------------------- | |
74eb47db | 70 | .SH "DESCRIPTION" |
fc916a09 | 71 | . |
74eb47db | 72 | The |
73 | .B tripe | |
74 | program is a server which can provide strong IP-level encryption and | |
1a19f865 | 75 | authentication between co-operating hosts. The program and its protocol |
76 | are deliberately very simple, to make analysing them easy and to help | |
77 | build trust rapidly in the system. | |
74eb47db | 78 | .SS "Overview" |
79 | The | |
80 | .B tripe | |
81 | server manages a number of secure connections to other `peer' hosts. | |
82 | Each daemon is given a private key of its own, and a file of public keys | |
83 | for the peers with which it is meant to communicate. It is responsible | |
84 | for negotiating sets of symmetric keys with its peers, and for | |
85 | encrypting, encapsulating and sending IP packets to its peers, and | |
86 | decrypting, checking and de-encapsulating packets it receives from | |
87 | them. | |
88 | .PP | |
89 | When the server starts, it creates a Unix-domain socket on which it | |
90 | listens for administration commands. It also logs warnings and | |
91 | diagnostic information to the programs connected to its admin socket. | |
92 | Clients connected to the socket can add new peers, and remove or find | |
93 | out about existing peers. The textual protocol used to give the | |
94 | .B tripe | |
95 | server admin commands is described in | |
96 | .BR tripe\-admin (5). | |
97 | A client program | |
98 | .BR tripectl (1) | |
99 | is provided to allow commands to be sent to the server either | |
100 | interactively or by simple scripts. | |
101 | .SS "Command-line arguments" | |
102 | If not given any command-line arguments, | |
103 | .B tripe | |
104 | will initialize by following these steps: | |
1a19f865 | 105 | .hP 1. |
106 | It sets the directory named by the | |
107 | .B TRIPEDIR | |
108 | environment variable (or | |
f7b5d108 | 109 | .B "\*(/c" |
1a19f865 | 110 | if the variable is unset) as the current directory. |
111 | .hP 2. | |
74eb47db | 112 | It acquires a UDP socket with an arbitrary kernel-selected port number. |
113 | It will use this socket to send and receive all communications with its | |
114 | peer servers. The port chosen may be discovered by means of the | |
115 | .B PORT | |
116 | admin command (see | |
117 | .BR tripe\-admin (5)). | |
1a19f865 | 118 | .hP 3. |
74eb47db | 119 | It loads the private key with the tag or type name |
fc5f4823 MW |
120 | .B tripe |
121 | (or, failing that, | |
74eb47db | 122 | .B tripe\-dh |
fc5f4823 | 123 | for backwards compatibility reasons) from the Catacomb-format file |
74eb47db | 124 | .BR keyring , |
125 | and loads the file | |
126 | .B keyring.pub | |
127 | ready for extracting the public keys of peers as they're introduced. | |
128 | (The format of these files is described in | |
129 | .BR keyring (5). | |
130 | They are maintained using the program | |
131 | .BR key (1) | |
132 | provided with the Catacomb distribution.) | |
1a19f865 | 133 | .hP 4. |
74eb47db | 134 | It creates and listens to the Unix-domain socket |
135 | .BR tripesock . | |
136 | .PP | |
137 | Following this, the server enters its main loop, accepting admin | |
138 | connections and obeying any administrative commands, and communicating | |
139 | with peers. It also treats its standard input and standard output | |
140 | streams as an admin connection, reading commands from standard input and | |
33ced0d3 | 141 | writing responses and diagnostics messages to standard output. Finally, |
142 | it will reload keys from its keyring files if it notices that they've | |
143 | changed (it checks inode number and modification time) \- there's no | |
144 | need to send a signal. | |
74eb47db | 145 | .PP |
146 | Much of this behaviour may be altered by giving | |
147 | .B tripe | |
148 | suitable command-line options: | |
149 | .TP | |
150 | .B "\-h, \-\-help" | |
151 | Writes a brief description of the command-line options available to | |
152 | standard output and exits with status 0. | |
153 | .TP | |
154 | .B "\-v, \-\-version" | |
155 | Writes | |
156 | .BR tripe 's | |
157 | version number to standard output and exits with status 0. | |
158 | .TP | |
159 | .B "\-u, \-\-usage" | |
160 | Writes a brief usage summary to standard output and exits with status 0. | |
161 | .TP | |
42da2a58 | 162 | .B "\-\-tunnels" |
163 | Writes to standard output a list of the configured tunnel drivers, one | |
164 | per line, and exits with status 0. This is intended for the use of the | |
3cdc3f3a | 165 | start-up script, so that it can check that it will actually work. |
166 | .TP | |
74eb47db | 167 | .B "\-D, \-\-daemon" |
168 | Dissociates from its terminal and starts running in the background after | |
169 | completing the initialization procedure described above. If running as | |
170 | a daemon, | |
171 | .B tripe | |
172 | will not read commands from standard input or write diagnostics to | |
173 | standard output. A better way to start | |
174 | .B tripe | |
175 | in the background is with | |
176 | .BR tripectl (1). | |
177 | .TP | |
46dde080 MW |
178 | .B "\-F, \-\-foreground" |
179 | Runs the server in the `foreground'; i.e., | |
180 | .B tripe | |
181 | will quit if it sees end-of-file on its standard input. This is | |
182 | incompatible with | |
183 | .BR \-D . | |
184 | .TP | |
74eb47db | 185 | .BI "\-d, \-\-directory=" dir |
186 | Makes | |
187 | .I dir | |
797cf76b MW |
188 | the current directory. The default directory to change to is given by |
189 | the environment variable | |
190 | .BR TRIPEDIR ; | |
191 | if that's not specified, a default default of | |
f7b5d108 | 192 | .B "\*(/c" |
797cf76b | 193 | is used. Give a current directory of |
74eb47db | 194 | .B . |
195 | if you don't want it to change directory at all. | |
196 | .TP | |
d13e5724 | 197 | .BI "\-b, \-\-bind-address="addr |
198 | Bind the UDP socket to IP address | |
199 | .I addr | |
200 | rather than the default of | |
201 | .BR INADDR_ANY . | |
202 | This is useful if your main globally-routable IP address is one you want | |
203 | to tunnel through the VPN. | |
204 | .TP | |
74eb47db | 205 | .BI "\-p, \-\-port=" port |
206 | Use the specified UDP port for all communications with peers, rather | |
207 | than an arbitarary kernel-assigned port. | |
208 | .TP | |
42da2a58 | 209 | .BI "\-n, \-\-tunnel=" tunnel |
210 | Use the specified tunnel driver for new peers by default. | |
211 | .TP | |
33ced0d3 | 212 | .BI "\-U, \-\-setuid=" user |
213 | Set uid to that of | |
214 | .I user | |
215 | (either a user name or integer uid) after initialization. Also set gid | |
216 | to | |
217 | .IR user 's | |
218 | primary group, unless overridden by a | |
219 | .B \-G | |
aa2405e8 MW |
220 | option. The selected user (and group) will also be the owner of the |
221 | administration socket. | |
33ced0d3 | 222 | .TP |
223 | .BI "\-G, \-\-setgid=" group | |
224 | Set gid to that of | |
225 | .I group | |
226 | (either a group name or integer gid) after initialization. | |
227 | .TP | |
74eb47db | 228 | .BI "\-k, \-\-priv\-keyring=" file |
229 | Reads the private key from | |
230 | .I file | |
231 | rather than the default | |
232 | .BR keyring . | |
233 | .TP | |
234 | .BI "\-K, \-\-pub\-keyring=" file | |
235 | Reads public keys from | |
236 | .I file | |
237 | rather than the default | |
238 | .BR keyring.pub . | |
239 | This can be the same as the private keyring, but that's not recommended. | |
240 | .TP | |
241 | .BI "\-t, \-\-tag=" tag | |
242 | Uses the private key whose tag or type is | |
243 | .I tag | |
244 | rather than the default | |
fc5f4823 MW |
245 | .B tripe |
246 | or | |
74eb47db | 247 | .BR tripe\-dh . |
248 | .TP | |
249 | .BI "\-a, \-\-admin\-socket=" socket | |
250 | Accept admin connections to a Unix-domain socket named | |
797cf76b MW |
251 | .IR socket . |
252 | The default socket, if this option isn't specified, is given by the | |
253 | environment variable | |
254 | .BR TRIPESOCK ; | |
255 | if that's not set either, then a default default of | |
f7b5d108 | 256 | .B "\*(/s/tripesock" |
797cf76b | 257 | is used instead. |
74eb47db | 258 | .TP |
259 | .BI "\-T, \-\-trace=" trace-opts | |
260 | Allows the enabling or disabling of various internal diagnostics. See | |
261 | below for the list of options. | |
fc5f4823 | 262 | .SS "Key exchange group types" |
d6623498 | 263 | The |
264 | .B tripe | |
fc5f4823 MW |
265 | server uses Diffie\(en\&Hellman key exchange to agree the symmetric keys |
266 | used for bulk data transfer. Currently | |
d6623498 | 267 | .B tripe |
fc5f4823 MW |
268 | can do Diffie\(en\&Hellman in two different kinds of cyclic groups: |
269 | .I "Schnorr groups" | |
270 | (denoted | |
271 | .BR dh ) | |
272 | and | |
273 | .I "elliptic curve groups" | |
274 | (denoted | |
275 | .BR ec ). | |
d6623498 | 276 | .PP |
fc5f4823 MW |
277 | A Schnorr group is a prime-order subgroup of the multiplicative group of |
278 | a finite field; this is the usual | |
279 | .I g\*(ssx\*(se | |
280 | mod | |
281 | .I p | |
282 | kind of Diffie\(en\&Hellman. An elliptic curve group is a prime-order | |
283 | subgroup of the abelian group of | |
284 | .BR K -rational | |
285 | points on an elliptic curve defined over a finite field | |
286 | .BR K . | |
287 | .PP | |
288 | Given current public knowledge, elliptic curves can provide similar or | |
289 | better security to systems based on integer discrete log problems, | |
290 | faster, and with less transmitted data. It's a matter of controversy | |
291 | whether this will continue to be the case. The author uses elliptic | |
292 | curves. | |
293 | .PP | |
294 | The server works out which it should be doing based on the key's | |
295 | .B kx-group | |
296 | attribute, which should be either | |
297 | .B dh | |
298 | or | |
299 | .BR ec . | |
300 | If this attribute isn't present, then the key's type is examined: if | |
301 | it's of the form | |
302 | .BR tripe\- group | |
303 | then the | |
304 | .I group | |
305 | is used. If no group is specified, | |
306 | .B dh | |
307 | is used as a fallback. | |
308 | .PP | |
309 | To create usual Schnorr-group keys, say something like | |
74eb47db | 310 | .VS |
fc5f4823 MW |
311 | key add \-adh-param \-LS \-b3072 \-B256 \e |
312 | \-eforever \-tparam tripe\-param kx-group=dh | |
74eb47db | 313 | .VE |
fc5f4823 | 314 | to construct a parameters key; and create the private keys by |
d6623498 | 315 | .VS |
316 | key add \-adh \-pparam \-talice \e | |
fc5f4823 | 317 | \-e"now + 1 year" tripe |
d6623498 | 318 | .VE |
fc5f4823 | 319 | To create elliptic curve keys, say something like |
d6623498 | 320 | .VS |
fc5f4823 MW |
321 | key add \-aec\-param \-Cnist-p256 \-eforever \e |
322 | \-tparam tripe\-param kx-group=ec | |
52c03a2a | 323 | .VE |
324 | to construct a parameters key, using your preferred elliptic curve in | |
325 | the | |
326 | .B \-C | |
327 | option (see | |
328 | .BR key (1) | |
329 | for details); and create the private keys by | |
330 | .VS | |
331 | key add \-aec \-pparam \-talice \e | |
fc5f4823 | 332 | \-e"now + 1 year" tripe |
52c03a2a | 333 | .VE |
fc5f4823 MW |
334 | Note that the |
335 | .BR tripe-keys (8) | |
336 | program provides a rather more convenient means for generating and | |
337 | managing keys for | |
338 | .BR tripe . | |
b5c45da1 | 339 | .SS "Using other symmetric algorithms" |
340 | The default symmetric algorithms | |
341 | .B tripe | |
342 | uses are Blowfish (by Schneier) for symmetric encryption, and RIPEMD-160 | |
343 | (by Dobbertin, Bosselaers and Preneel) for hashing and as a MAC (in HMAC | |
344 | mode, designed by Bellare, Canetti and Krawczyk). These can all be | |
345 | overridden by setting attributes on your private key, as follows. | |
346 | .TP | |
347 | .B cipher | |
348 | Names the symmetric encryption scheme to use. The default is | |
349 | .BR blowfish\-cbc . | |
350 | .TP | |
351 | .B hash | |
352 | Names the hash function to use. The default is | |
353 | .BR rmd160 . | |
354 | .TP | |
355 | .B mac | |
356 | Names the message authentication code to use. The name of the MAC may | |
357 | be followed by a | |
358 | .RB ` / ' | |
359 | and the desired tag length in bits. The default is | |
360 | .IB hash \-hmac | |
361 | at half the underlying hash function's output length. | |
362 | .TP | |
363 | .B mgf | |
364 | A `mask-generation function', used in the key-exchange. The default is | |
365 | .IB hash \-mgf | |
366 | and there's no good reason to change it. | |
b9066fbb | 367 | .SS "Using SLIP interfaces" |
368 | Though not for the faint of heart, it is possible to get | |
369 | .B tripe | |
370 | to read and write network packets to a pair of file descriptors using | |
371 | SLIP encapsulation. No fancy header compression of any kind is | |
98fdb08d | 372 | supported. |
373 | .PP | |
374 | Two usage modes are supported: a preallocation system, whereby SLIP | |
375 | interfaces are created and passed to the | |
376 | .B tripe | |
377 | server at startup; and a dynamic system, where the server runs a script | |
378 | to allocate a new SLIP interface when it needs one. It is possible to | |
379 | use a mixture of these two modes, starting | |
b9066fbb | 380 | .B tripe |
98fdb08d | 381 | with a few preallocated interfaces and having it allocate more |
382 | dynamically as it needs them. | |
383 | .PP | |
384 | The behaviour of | |
385 | .BR tripe 's | |
386 | SLIP driver is controlled by the | |
387 | .B TRIPE_SLIPIF | |
1f68dfc5 | 388 | environment variable. The server will not create SLIP tunnels if this |
389 | variable is not defined. The variable's value is a colon-delimited list | |
390 | of preallocated interfaces, followed optionally by the filename of a | |
391 | script to run to dynamically allocate more interfaces. | |
b9066fbb | 392 | .PP |
98fdb08d | 393 | A static allocation entry has the form |
b9066fbb | 394 | .IR infd [ \c |
395 | .BI , outfd \c | |
396 | .RB ] \c | |
397 | .BI = \c | |
98fdb08d | 398 | .IR ifname , |
b9066fbb | 399 | If the |
400 | .I outfd | |
401 | is omitted, the same file descriptor is used for input and output. | |
402 | .PP | |
98fdb08d | 403 | The dynamic allocation script must be named by an absolute or relative |
e04c2d50 | 404 | pathname, beginning with |
98fdb08d | 405 | .RB ` / ' |
406 | or | |
407 | .RB ` . '. | |
408 | The server will pass the script an argument, which is the name of the | |
409 | peer for which the interface is being created. The script should | |
410 | allocate a new SLIP interface (presumably by creating a pty pair), | |
411 | configure it appropriately, and write the interface's name to its | |
412 | standard output, followed by a newline. It should then read and write | |
413 | SLIP packets on its stdin and stdout. The script's stdin will be closed | |
414 | when the interface is no longer needed, and the server will attempt to | |
415 | send it a | |
416 | .B SIGTERM | |
417 | signal (though this may fail if the script runs with higher privileges | |
418 | than the server). | |
419 | .PP | |
b9066fbb | 420 | The output file descriptor should not block unless it really needs to: |
421 | the | |
422 | .B tripe | |
1f68dfc5 | 423 | daemon assumes that it won't, and will get wedged waiting for it to |
424 | accept output. | |
74eb47db | 425 | .SS "About the name" |
426 | The program's name is | |
427 | .BR tripe , | |
428 | all in lower-case. The name of the protocol it uses is `TrIPE', with | |
429 | four capital letters and one lower-case. The name stands for `Trivial | |
430 | IP Encryption'. | |
fc916a09 MW |
431 | . |
432 | .\"-------------------------------------------------------------------------- | |
74eb47db | 433 | .SH "BUGS" |
fc916a09 | 434 | . |
74eb47db | 435 | The code hasn't been audited. It may contain security bugs. If you |
436 | find one, please inform the author | |
437 | .IR immediately . | |
fc916a09 MW |
438 | . |
439 | .\"-------------------------------------------------------------------------- | |
74eb47db | 440 | .SH "SEE ALSO" |
fc916a09 | 441 | . |
74eb47db | 442 | .BR key (1), |
443 | .BR tripectl (1), | |
fc5f4823 MW |
444 | .BR tripe\-admin (5), |
445 | .BR tripe\-keys (8). | |
74eb47db | 446 | .PP |
447 | .IR "The Trivial IP Encryption Protocol" , | |
448 | .IR "The Wrestlers Protocol" . | |
fc916a09 MW |
449 | . |
450 | .\"-------------------------------------------------------------------------- | |
74eb47db | 451 | .SH "AUTHOR" |
fc916a09 | 452 | . |
d36eda2a | 453 | Mark Wooding, <mdw@distorted.org.uk> |
fc916a09 MW |
454 | . |
455 | .\"----- That's all, folks -------------------------------------------------- |