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Revision: 1.32
Committed: Thu Jul 18 13:35:19 2013 UTC (10 years, 10 months ago) by root
Branch: MAIN
Changes since 1.31: +819 -0 lines
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124     .\" ========================================================================
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126     .IX Title "GVPE.CONF 5"
127     .TH GVPE.CONF 5 "2013-07-17" "2.25" "GNU Virtual Private Ethernet"
128     .\" For nroff, turn off justification. Always turn off hyphenation; it makes
129     .\" way too many mistakes in technical documents.
130     .if n .ad l
131     .nh
132     .SH "NAME"
133     gvpe.conf \- configuration file for the GNU VPE daemon
134     .SH "SYNOPSIS"
135     .IX Header "SYNOPSIS"
136     .Vb 4
137     \& # global options for all nodes
138     \& udp\-port = 407
139     \& mtu = 1492
140     \& ifname = vpn0
141     \&
142     \& # first node is named branch1 and is at 1.2.3.4
143     \& node = branch1
144     \& hostname = 1.2.3.4
145     \&
146     \& # second node uses dns to resolve the address
147     \& node = branch2
148     \& hostname = www.example.net
149     \& udp\-port = 500 # this host uses a different udp\-port
150     \&
151     \& # third node has no fixed ip address
152     \& node = branch3
153     \& connect = ondemand
154     .Ve
155     .SH "DESCRIPTION"
156     .IX Header "DESCRIPTION"
157     The gvpe config file consists of a series of lines that contain \f(CW\*(C`variable
158     = value\*(C'\fR pairs. Empty lines are ignored. Comments start with a \f(CW\*(C`#\*(C'\fR and
159     extend to the end of the line. They can be used on their own lines, or
160     after any directives. Whitespace is allowed around the \f(CW\*(C`=\*(C'\fR sign or after
161     values, but not within the variable names or values themselves.
162     .PP
163     All settings are applied \*(L"in order\*(R", that is, later settings of the same
164     variable overwrite earlier ones.
165     .PP
166     The only exceptions to the above are the following directives:
167     .IP "node nodename" 4
168     .IX Item "node nodename"
169     Introduces a node section. The nodename is used to select the right
170     configuration section and is the same string as is passed as an argument
171     to the gvpe daemon.
172     .Sp
173     Multiple \f(CW\*(C`node\*(C'\fR statements with the same node name are supported and will
174     be merged together.
175     .IP "global" 4
176     .IX Item "global"
177     This statement switches back to the global section, which is mainly
178     useful if you want to include a second config file, e..g for local
179     customisations. To do that, simply include this at the very end of your
180     config file:
181     .Sp
182     .Vb 2
183     \& global
184     \& include local.conf
185     .Ve
186     .IP "on nodename ..." 4
187     .IX Item "on nodename ..."
188     .PD 0
189     .IP "on !nodename ..." 4
190     .IX Item "on !nodename ..."
191     .PD
192     You can prefix any configuration directive with \f(CW\*(C`on\*(C'\fR and a nodename. \s-1GVPE\s0
193     will will only \*(L"execute\*(R" it on the named node, or (if the nodename starts
194     with \f(CW\*(C`!\*(C'\fR) on all nodes except the named one.
195     .Sp
196     Example: set the \s-1MTU\s0 to \f(CW1450\fR everywhere, \f(CW\*(C`loglevel\*(C'\fR to \f(CW\*(C`noise\*(C'\fR on
197     \&\f(CW\*(C`branch1\*(C'\fR, and \f(CW\*(C`connect\*(C'\fR to \f(CW\*(C`ondemand\*(C'\fR everywhere but on branch2.
198     .Sp
199     .Vb 3
200     \& mtu = 1450
201     \& on branch1 loglevel = noise
202     \& on !branch2 connect = ondemand
203     .Ve
204     .IP "include relative-or-absolute-path" 4
205     .IX Item "include relative-or-absolute-path"
206     Reads the specified file (the path must not contain whitespace or \f(CW\*(C`=\*(C'\fR
207     characters) and evaluate all config directives in it as if they were
208     spelled out in place of the \f(CW\*(C`include\*(C'\fR directive.
209     .Sp
210     The path is a printf format string, that is, you must escape any \f(CW\*(C`%\*(C'\fR
211     by doubling it, and you can have a single \f(CW%s\fR inside, which will be
212     replaced by the current nodename.
213     .Sp
214     Relative paths are interpreted relative to the \s-1GVPE\s0 config directory.
215     .Sp
216     Example: include the file \fIlocal.conf\fR in the config directory on every
217     node.
218     .Sp
219     .Vb 1
220     \& include local.conf
221     .Ve
222     .Sp
223     Example: include a file \fIconf/\fRnodename\fI.conf\fR
224     .Sp
225     .Vb 1
226     \& include conf/%s.conf
227     .Ve
228     .SH "ANATOMY OF A CONFIG FILE"
229     .IX Header "ANATOMY OF A CONFIG FILE"
230     Usually, a config file starts with a few global settings (like the \s-1UDP\s0
231     port to listen on), followed by node-specific sections that begin with a
232     \&\f(CW\*(C`node = nickname\*(C'\fR line.
233     .PP
234     Every node that is part of the network must have a section that starts
235     with \f(CW\*(C`node = nickname\*(C'\fR. The number and order of the nodes is important
236     and must be the same on all nodes. It is not uncommon for node sections to
237     be completely empty \- if the default values are right.
238     .PP
239     Node-specific settings can be used at any time. If used before the first
240     node section they will set the default values for all following nodes.
241     .SH "CONFIG VARIABLES"
242     .IX Header "CONFIG VARIABLES"
243     .SS "\s-1GLOBAL\s0 \s-1SETTINGS\s0"
244     .IX Subsection "GLOBAL SETTINGS"
245     Global settings will affect the behaviour of the running gvpe daemon, that
246     is, they are in some sense node-specific (config files can set different
247     values on different nodes using \f(CW\*(C`on\*(C'\fR), but will affect the behaviour of
248     the gvpe daemon and all connections it creates.
249     .IP "chroot = path or /" 4
250     .IX Item "chroot = path or /"
251     Tells \s-1GVPE\s0 to \fIchroot\fR\|(2) to the specified path after reading all necessary
252     files, binding to sockets and running the \f(CW\*(C`if\-up\*(C'\fR script, but before
253     running \f(CW\*(C`node\-up\*(C'\fR or any other scripts.
254     .Sp
255     The special path \fI/\fR instructs \s-1GVPE\s0 to create (and remove) an empty
256     temporary directory to use as new root. This is most secure, but makes it
257     impossible to use any scripts other than the \f(CW\*(C`if\-up\*(C'\fR one.
258     .IP "chuid = numerical-uid" 4
259     .IX Item "chuid = numerical-uid"
260     .PD 0
261     .IP "chgid = numerical-gid" 4
262     .IX Item "chgid = numerical-gid"
263     .PD
264     These two options tell \s-1GVPE\s0 to change to the given user and/or group id
265     after reading all necessary files, binding to sockets and running the
266     \&\f(CW\*(C`if\-up\*(C'\fR script.
267     .Sp
268     Other scripts, such as \f(CW\*(C`node\-up\*(C'\fR, are run with the new user id or group id.
269     .IP "chuser = username" 4
270     .IX Item "chuser = username"
271     Alternative to \f(CW\*(C`chuid\*(C'\fR and \f(CW\*(C`chgid\*(C'\fR: Sets both \f(CW\*(C`chuid\*(C'\fR and \f(CW\*(C`chgid\*(C'\fR
272     to the user and (primary) group ids of the specified user (for example,
273     \&\f(CW\*(C`nobody\*(C'\fR).
274     .IP "dns-forw-host = hostname/ip" 4
275     .IX Item "dns-forw-host = hostname/ip"
276     The \s-1DNS\s0 server to forward \s-1DNS\s0 requests to for the \s-1DNS\s0 tunnel protocol
277     (default: \f(CW127.0.0.1\fR, changing it is highly recommended).
278     .IP "dns-forw-port = port-number" 4
279     .IX Item "dns-forw-port = port-number"
280     The port where the \f(CW\*(C`dns\-forw\-host\*(C'\fR is to be contacted (default: \f(CW53\fR,
281     which is fine in most cases).
282     .IP "dns-case-preserving = yes|true|on | no|false|off" 4
283     .IX Item "dns-case-preserving = yes|true|on | no|false|off"
284     Sets whether the \s-1DNS\s0 transport forwarding server preserves case (\s-1DNS\s0
285     servers have to, but some access systems are even more broken than others)
286     (default: true).
287     .Sp
288     Normally, when the forwarding server changes the case of domain names then
289     \&\s-1GVPE\s0 will automatically set this to false.
290     .IP "dns-max-outstanding = integer-number-of-requests" 4
291     .IX Item "dns-max-outstanding = integer-number-of-requests"
292     The maximum number of outstanding \s-1DNS\s0 transport requests
293     (default: \f(CW100\fR). \s-1GVPE\s0 will never issue more requests then the given
294     limit without receiving replies. In heavily overloaded situations it might
295     help to set this to a low number (e.g. \f(CW3\fR or even \f(CW1\fR) to limit the
296     number of parallel requests.
297     .Sp
298     The default should be working \s-1OK\s0 for most links.
299     .IP "dns-overlap-factor = float" 4
300     .IX Item "dns-overlap-factor = float"
301     The \s-1DNS\s0 transport uses the minimum request latency (\fBmin_latency\fR) seen
302     during a connection as it's timing base. This factor (default: \f(CW0.5\fR,
303     must be > 0) is multiplied by \fBmin_latency\fR to get the maximum sending
304     rate (= minimum send interval), i.e. a factor of \f(CW1\fR means that a new
305     request might be generated every \fBmin_latency\fR seconds, which means on
306     average there should only ever be one outstanding request. A factor of
307     \&\f(CW0.5\fR means that \s-1GVPE\s0 will send requests twice as often as the minimum
308     latency measured.
309     .Sp
310     For congested or picky \s-1DNS\s0 forwarders you could use a value nearer to or
311     exceeding \f(CW1\fR.
312     .Sp
313     The default should be working \s-1OK\s0 for most links.
314     .IP "dns-send-interval = send-interval-in-seconds" 4
315     .IX Item "dns-send-interval = send-interval-in-seconds"
316     The minimum send interval (= maximum rate) that the \s-1DNS\s0 transport will
317     use to send new \s-1DNS\s0 requests. \s-1GVPE\s0 will not exceed this rate even when
318     the latency is very low. The default is \f(CW0.01\fR, which means \s-1GVPE\s0 will
319     not send more than 100 \s-1DNS\s0 requests per connection per second. For
320     high-bandwidth links you could go lower, e.g. to \f(CW0.001\fR or so. For
321     congested or rate-limited links, you might want to go higher, say \f(CW0.1\fR,
322     \&\f(CW0.2\fR or even higher.
323     .Sp
324     The default should be working \s-1OK\s0 for most links.
325     .IP "dns-timeout-factor = float" 4
326     .IX Item "dns-timeout-factor = float"
327     Factor to multiply the \f(CW\*(C`min_latency\*(C'\fR (see \f(CW\*(C`dns\-overlap\-factor\*(C'\fR) by to
328     get request timeouts. The default of \f(CW8\fR means that the \s-1DNS\s0 transport
329     will resend the request when no reply has been received for longer than
330     eight times the minimum (= expected) latency, assuming the request or
331     reply has been lost.
332     .Sp
333     For congested links a higher value might be necessary (e.g. \f(CW30\fR). If
334     the link is very stable lower values (e.g. \f(CW2\fR) might work
335     nicely. Values near or below \f(CW1\fR makes no sense whatsoever.
336     .Sp
337     The default should be working \s-1OK\s0 for most links but will result in low
338     throughput if packet loss is high.
339     .IP "if-up = relative-or-absolute-path" 4
340     .IX Item "if-up = relative-or-absolute-path"
341     Sets the path of a script that should be called immediately after the
342     network interface is initialized (but not necessarily up). The following
343     environment variables are passed to it (the values are just examples).
344     .Sp
345     Variables that have the same value on all nodes:
346     .RS 4
347     .IP "CONFBASE=/etc/gvpe" 4
348     .IX Item "CONFBASE=/etc/gvpe"
349     The configuration base directory.
350     .IP "IFNAME=vpn0" 4
351     .IX Item "IFNAME=vpn0"
352     The network interface to initialize.
353     .IP "IFTYPE=native # or tincd" 4
354     .IX Item "IFTYPE=native # or tincd"
355     .PD 0
356     .IP "IFSUBTYPE=linux # or freebsd, darwin etc.." 4
357     .IX Item "IFSUBTYPE=linux # or freebsd, darwin etc.."
358     .PD
359     The interface type (\f(CW\*(C`native\*(C'\fR or \f(CW\*(C`tincd\*(C'\fR) and the subtype (usually the
360     \&\s-1OS\s0 name in lowercase) that this \s-1GVPE\s0 was configured for. Can be used to
361     select the correct syntax to use for network-related commands.
362     .IP "MTU=1436" 4
363     .IX Item "MTU=1436"
364     The \s-1MTU\s0 to set the interface to. You can use lower values (if done
365     consistently on all nodes), but this is usually either inefficient or
366     simply ineffective.
367     .IP "NODES=5" 4
368     .IX Item "NODES=5"
369     The number of nodes in this \s-1GVPE\s0 network.
370     .RE
371     .RS 4
372     .Sp
373     Variables that are node-specific and with values pertaining to the node
374     running this \s-1GVPE:\s0
375     .IP "IFUPDATA=string" 4
376     .IX Item "IFUPDATA=string"
377     The value of the configuration directive \f(CW\*(C`if\-up\-data\*(C'\fR.
378     .IP "MAC=fe:fd:80:00:00:01" 4
379     .IX Item "MAC=fe:fd:80:00:00:01"
380     The \s-1MAC\s0 address the network interface has to use.
381     .Sp
382     Might be used to initialize interfaces on platforms where \s-1GVPE\s0 does not
383     do this automatically. Please see the \f(CW\*(C`gvpe.osdep(5)\*(C'\fR man page for
384     platform-specific information.
385     .IP "NODENAME=branch1" 4
386     .IX Item "NODENAME=branch1"
387     The nickname of the node.
388     .IP "NODEID=1" 4
389     .IX Item "NODEID=1"
390     The numerical node \s-1ID\s0 of the node running this instance of \s-1GVPE\s0. The first
391     node mentioned in the config file gets \s-1ID\s0 1, the second \s-1ID\s0 2 and so on.
392     .RE
393     .RS 4
394     .Sp
395     In addition, all node-specific variables (except \f(CW\*(C`NODEID\*(C'\fR) will be
396     available with a postfix of \f(CW\*(C`_nodeid\*(C'\fR, which contains the value for that
397     node, e.g. the \f(CW\*(C`MAC_1\*(C'\fR variable contains the \s-1MAC\s0 address of node #1, while
398     the \f(CW\*(C`NODENAME_22\*(C'\fR variable contains the name of node #22.
399     .Sp
400     Here is a simple if-up script:
401     .Sp
402     .Vb 5
403     \& #!/bin/sh
404     \& ip link set $IFNAME up
405     \& [ $NODENAME = branch1 ] && ip addr add 10.0.0.1 dev $IFNAME
406     \& [ $NODENAME = branch2 ] && ip addr add 10.1.0.1 dev $IFNAME
407     \& ip route add 10.0.0.0/8 dev $IFNAME
408     .Ve
409     .Sp
410     More complicated examples (using routing to reduce \s-1ARP\s0 traffic) can be
411     found in the \fIetc/\fR subdirectory of the distribution.
412     .RE
413     .IP "ifname = devname" 4
414     .IX Item "ifname = devname"
415     Sets the tun interface name to the given name. The default is OS-specific
416     and most probably something like \f(CW\*(C`tun0\*(C'\fR.
417     .IP "ifpersist = yes|true|on | no|false|off" 4
418     .IX Item "ifpersist = yes|true|on | no|false|off"
419     Should the tun/tap device be made persistent, that is, should the device
420     stay up even when gvpe exits? Some versions of the tunnel device have
421     problems sending packets when gvpe is restarted in persistent mode, so
422     if the connections can be established but you cannot send packets from
423     the local node, try to set this to \f(CW\*(C`off\*(C'\fR and do an ifconfig down on the
424     device.
425     .IP "ip-proto = numerical-ip-protocol" 4
426     .IX Item "ip-proto = numerical-ip-protocol"
427     Sets the protocol number to be used for the rawip protocol. This is a
428     global option because all nodes must use the same protocol, and since
429     there are no port numbers, you cannot easily run more than one gvpe
430     instance using the same protocol, nor can you share the protocol with
431     other programs.
432     .Sp
433     The default is 47 (\s-1GRE\s0), which has a good chance of tunneling
434     through firewalls (but note that gvpe's rawip protocol is not \s-1GRE\s0
435     compatible). Other common choices are 50 (\s-1IPSEC\s0, \s-1ESP\s0), 51 (\s-1IPSEC\s0, \s-1AH\s0), 4
436     (\s-1IPIP\s0 tunnels) or 98 (\s-1ENCAP\s0, rfc1241).
437     .Sp
438     Many versions of Linux seem to have a bug that causes them to reorder
439     packets for some ip protocols (\s-1GRE\s0, \s-1ESP\s0) but not for others (\s-1AH\s0), so
440     choose wisely (that is, use 51, \s-1AH\s0).
441     .IP "http-proxy-host = hostname/ip" 4
442     .IX Item "http-proxy-host = hostname/ip"
443     The \f(CW\*(C`http\-proxy\-*\*(C'\fR family of options are only available if gvpe was
444     compiled with the \f(CW\*(C`\-\-enable\-http\-proxy\*(C'\fR option and enable tunneling of
445     tcp connections through a http proxy server.
446     .Sp
447     \&\f(CW\*(C`http\-proxy\-host\*(C'\fR and \f(CW\*(C`http\-proxy\-port\*(C'\fR should specify the hostname and
448     port number of the proxy server. See \f(CW\*(C`http\-proxy\-loginpw\*(C'\fR if your proxy
449     requires authentication.
450     .Sp
451     Please note that gvpe will still try to resolve all hostnames in the
452     configuration file, so if you are behind a proxy without access to a \s-1DNS\s0
453     server better use numerical \s-1IP\s0 addresses.
454     .Sp
455     To make best use of this option disable all protocols except \s-1TCP\s0 in your
456     config file and make sure your routers (or all other nodes) are listening
457     on a port that the proxy allows (443, https, is a common choice).
458     .Sp
459     If you have a router, connecting to it will suffice. Otherwise \s-1TCP\s0 must be
460     enabled on all nodes.
461     .Sp
462     Example:
463     .Sp
464     .Vb 3
465     \& http\-proxy\-host = proxy.example.com
466     \& http\-proxy\-port = 3128 # 8080 is another common choice
467     \& http\-proxy\-auth = schmorp:grumbeere
468     .Ve
469     .IP "http-proxy-port = proxy-tcp-port" 4
470     .IX Item "http-proxy-port = proxy-tcp-port"
471     The port where your proxy server listens.
472     .IP "http-proxy-auth = login:password" 4
473     .IX Item "http-proxy-auth = login:password"
474     The optional login and password used to authenticate to the proxy server,
475     separated by a literal colon (\f(CW\*(C`:\*(C'\fR). Only basic authentication is
476     currently supported.
477     .IP "keepalive = seconds" 4
478     .IX Item "keepalive = seconds"
479     Sets the keepalive probe interval in seconds (default: \f(CW60\fR). After this
480     many seconds of inactivity the daemon will start to send keepalive probe
481     every 3 seconds until it receives a reply from the other end. If no reply
482     is received within 15 seconds, the peer is considered unreachable and the
483     connection is closed.
484     .IP "loglevel = noise|trace|debug|info|notice|warn|error|critical" 4
485     .IX Item "loglevel = noise|trace|debug|info|notice|warn|error|critical"
486     Set the logging level. Connection established messages are logged at level
487     \&\f(CW\*(C`info\*(C'\fR, notable errors are logged with \f(CW\*(C`error\*(C'\fR. Default is \f(CW\*(C`info\*(C'\fR.
488     .IP "mtu = bytes" 4
489     .IX Item "mtu = bytes"
490     Sets the maximum \s-1MTU\s0 that should be used on outgoing packets (basically
491     the \s-1MTU\s0 of the outgoing interface) The daemon will automatically calculate
492     maximum overhead (e.g. \s-1UDP\s0 header size, encryption blocksize...) and pass
493     this information to the \f(CW\*(C`if\-up\*(C'\fR script.
494     .Sp
495     Recommended values are 1500 (ethernet), 1492 (pppoe), 1472 (pptp).
496     .Sp
497     This value must be the minimum of the \s-1MTU\s0 values of all nodes.
498     .IP "nfmark = integer" 4
499     .IX Item "nfmark = integer"
500     This advanced option, when set to a nonzero value (default: \f(CW0\fR), tries
501     to set the netfilter mark (or fwmark) value on all sockets gvpe uses to
502     send packets.
503     .Sp
504     This can be used to make gvpe use a different set of routing rules. For
505     example, on GNU/Linux, the \f(CW\*(C`if\-up\*(C'\fR could set \f(CW\*(C`nfmark\*(C'\fR to 1000 and then
506     put all routing rules into table \f(CW99\fR and then use an ip rule to make
507     gvpe traffic avoid that routing table, in effect routing normal traffic
508     via gvpe and gvpe traffic via the normal system routing tables:
509     .Sp
510     .Vb 1
511     \& ip rule add not fwmark 1000 lookup 99
512     .Ve
513     .IP "node-up = relative-or-absolute-path" 4
514     .IX Item "node-up = relative-or-absolute-path"
515     Sets a command (default: none) that should be called whenever a connection
516     is established (even on rekeying operations). Note that node\-up/down
517     scripts will be run asynchronously, but execution is serialised, so there
518     will only ever be one such script running.
519     .Sp
520     In addition to all the variables passed to \f(CW\*(C`if\-up\*(C'\fR scripts, the following
521     environment variables will be set (values are just examples):
522     .RS 4
523     .IP "DESTNODE=branch2" 4
524     .IX Item "DESTNODE=branch2"
525     The name of the remote node.
526     .IP "DESTID=2" 4
527     .IX Item "DESTID=2"
528     The node id of the remote node.
529     .IP "DESTSI=rawip/88.99.77.55:0" 4
530     .IX Item "DESTSI=rawip/88.99.77.55:0"
531     The \*(L"socket info\*(R" of the target node, protocol dependent but usually in
532     the format protocol/ip:port.
533     .IP "DESTIP=188.13.66.8" 4
534     .IX Item "DESTIP=188.13.66.8"
535     The numerical \s-1IP\s0 address of the remote node (gvpe accepts connections from
536     everywhere, as long as the other node can authenticate itself).
537     .IP "DESTPORT=655 # deprecated" 4
538     .IX Item "DESTPORT=655 # deprecated"
539     The protocol port used by the other side, if applicable.
540     .IP "STATE=up" 4
541     .IX Item "STATE=up"
542     Node-up scripts get called with STATE=up, node-change scripts get called
543     with STATE=change and node-down scripts get called with STATE=down.
544     .RE
545     .RS 4
546     .Sp
547     Here is a nontrivial example that uses nsupdate to update the name => ip
548     mapping in some \s-1DNS\s0 zone:
549     .Sp
550     .Vb 6
551     \& #!/bin/sh
552     \& {
553     \& echo update delete $DESTNODE.lowttl.example.net. a
554     \& echo update add $DESTNODE.lowttl.example.net. 1 in a $DESTIP
555     \& echo
556     \& } | nsupdate \-d \-k $CONFBASE:key.example.net.
557     .Ve
558     .RE
559     .IP "node-change = relative-or-absolute-path" 4
560     .IX Item "node-change = relative-or-absolute-path"
561     Same as \f(CW\*(C`node\-change\*(C'\fR, but gets called whenever something about a
562     connection changes (such as the source \s-1IP\s0 address).
563     .IP "node-down = relative-or-absolute-path" 4
564     .IX Item "node-down = relative-or-absolute-path"
565     Same as \f(CW\*(C`node\-up\*(C'\fR, but gets called whenever a connection is lost.
566     .IP "pid-file = path" 4
567     .IX Item "pid-file = path"
568     The path to the pid file to check and create
569     (default: \f(CW\*(C`LOCALSTATEDIR/run/gvpe.pid\*(C'\fR). The first \f(CW%s\fR is replaced by
570     the nodename \- any other use of \f(CW\*(C`%\*(C'\fR must be written as \f(CW\*(C`%%\*(C'\fR.
571     .IP "private-key = relative-path-to-key" 4
572     .IX Item "private-key = relative-path-to-key"
573     Sets the path (relative to the config directory) to the private key
574     (default: \f(CW\*(C`hostkey\*(C'\fR). This is a printf format string so every \f(CW\*(C`%\*(C'\fR must
575     be doubled. A single \f(CW%s\fR is replaced by the hostname, so you could
576     use paths like \f(CW\*(C`hostkeys/%s\*(C'\fR to fetch the files at the location where
577     \&\f(CW\*(C`gvpectrl\*(C'\fR puts them.
578     .Sp
579     Since only the private key file of the current node is used and the
580     private key file should be kept secret per-node to avoid spoofing, it is
581     not recommended to use this feature.
582     .IP "rekey = seconds" 4
583     .IX Item "rekey = seconds"
584     Sets the rekeying interval in seconds (default: \f(CW3607\fR). Connections are
585     reestablished every \f(CW\*(C`rekey\*(C'\fR seconds, making them use a new encryption
586     key.
587     .IP "seed-device = path" 4
588     .IX Item "seed-device = path"
589     The random device used to initially and regularly seed the random
590     number generator (default: \fI/dev/urandom\fR). Randomness is of paramount
591     importance to the security of the algorithms used in gvpe.
592     .Sp
593     On program start and every seed-interval, gvpe will read 64 octets.
594     .Sp
595     Setting this path to the empty string will disable this functionality
596     completely (the underlying crypto library will likely look for entropy
597     sources on it's own though, so not all is lost).
598     .IP "seed-interval = seconds" 4
599     .IX Item "seed-interval = seconds"
600     The number of seconds between reseeds of the random number generator
601     (default: \f(CW3613\fR). A value of \f(CW0\fR disables this regular reseeding.
602     .SS "\s-1NODE\s0 \s-1SPECIFIC\s0 \s-1SETTINGS\s0"
603     .IX Subsection "NODE SPECIFIC SETTINGS"
604     The following settings are node-specific, that is, every node can have
605     different settings, even within the same gvpe instance. Settings that are
606     set before the first node section set the defaults, settings that are
607     set within a node section only apply to the given node.
608     .IP "allow-direct = nodename" 4
609     .IX Item "allow-direct = nodename"
610     Allow direct connections to this node. See \f(CW\*(C`deny\-direct\*(C'\fR for more info.
611     .IP "compress = yes|true|on | no|false|off" 4
612     .IX Item "compress = yes|true|on | no|false|off"
613     For the current node, this specified whether it will accept compressed
614     packets, and for all other nodes, this specifies whether to try to
615     compress data packets sent to this node (default: \f(CW\*(C`yes\*(C'\fR). Compression is
616     really cheap even on slow computers, has no size overhead at all and will
617     only be used when the other side supports compression, so enabling this is
618     often a good idea.
619     .IP "connect = ondemand | never | always | disabled" 4
620     .IX Item "connect = ondemand | never | always | disabled"
621     Sets the connect mode (default: \f(CW\*(C`always\*(C'\fR). It can be \f(CW\*(C`always\*(C'\fR (always
622     try to establish and keep a connection to the given node), \f(CW\*(C`never\*(C'\fR
623     (never initiate a connection to the given host, but accept connections),
624     \&\f(CW\*(C`ondemand\*(C'\fR (try to establish a connection when there are outstanding
625     packets in the queue and take it down after the keepalive interval) or
626     \&\f(CW\*(C`disabled\*(C'\fR (node is bad, don't talk to it).
627     .Sp
628     Routers will automatically be forced to \f(CW\*(C`always\*(C'\fR unless they are
629     \&\f(CW\*(C`disabled\*(C'\fR, to ensure all nodes can talk to each other.
630     .IP "deny-direct = nodename | *" 4
631     .IX Item "deny-direct = nodename | *"
632     Deny direct connections to the specified node (or all nodes when \f(CW\*(C`*\*(C'\fR
633     is given). Only one node can be specified, but you can use multiple
634     \&\f(CW\*(C`allow\-direct\*(C'\fR and \f(CW\*(C`deny\-direct\*(C'\fR statements. This only makes sense in
635     networks with routers, as routers are required for indirect connections.
636     .Sp
637     Sometimes, a node cannot reach some other nodes for reasons of network
638     connectivity. For example, a node behind a firewall that only allows
639     connections to/from a single other node in the network. In this case one
640     should specify \f(CW\*(C`deny\-direct = *\*(C'\fR and \f(CW\*(C`allow\-direct = othernodename\*(C'\fR (the other
641     node \fImust\fR be a router for this to work).
642     .Sp
643     The algorithm to check whether a connection may be direct is as follows:
644     .Sp
645     1. Other node mentioned in an \f(CW\*(C`allow\-direct\*(C'\fR? If yes, allow the connection.
646     .Sp
647     2. Other node mentioned in a \f(CW\*(C`deny\-direct\*(C'\fR? If yes, deny direct connections.
648     .Sp
649     3. Allow the connection.
650     .Sp
651     That is, \f(CW\*(C`allow\-direct\*(C'\fR takes precedence over \f(CW\*(C`deny\-direct\*(C'\fR.
652     .Sp
653     The check is done in both directions, i.e. both nodes must allow a direct
654     connection before one is attempted, so you only need to specify connect
655     limitations on one node.
656     .IP "dns-domain = domain-suffix" 4
657     .IX Item "dns-domain = domain-suffix"
658     The \s-1DNS\s0 domain suffix that points to the \s-1DNS\s0 tunnel server for this node.
659     .Sp
660     The domain must point to a \s-1NS\s0 record that points to the \fIdns-hostname\fR,
661     i.e.
662     .Sp
663     .Vb 2
664     \& dns\-domainname = tunnel.example.net
665     \& dns\-hostname = tunnel\-server.example.net
666     .Ve
667     .Sp
668     Corresponds to the following \s-1DNS\s0 entries in the \f(CW\*(C`example.net\*(C'\fR domain:
669     .Sp
670     .Vb 2
671     \& tunnel.example.net. NS tunnel\-server.example.net.
672     \& tunnel\-server.example.net. A 13.13.13.13
673     .Ve
674     .IP "dns-hostname = hostname/ip" 4
675     .IX Item "dns-hostname = hostname/ip"
676     The address to bind the \s-1DNS\s0 tunnel socket to, similar to the \f(CW\*(C`hostname\*(C'\fR,
677     but for the \s-1DNS\s0 tunnel protocol only. Default: \f(CW0.0.0.0\fR, but that might
678     change.
679     .IP "dns-port = port-number" 4
680     .IX Item "dns-port = port-number"
681     The port to bind the \s-1DNS\s0 tunnel socket to. Must be \f(CW53\fR on \s-1DNS\s0 tunnel servers.
682     .IP "enable-dns = yes|true|on | no|false|off" 4
683     .IX Item "enable-dns = yes|true|on | no|false|off"
684     See \fIgvpe.protocol\fR\|(7) for a description of the \s-1DNS\s0 transport
685     protocol. Avoid this protocol if you can.
686     .Sp
687     Enable the \s-1DNS\s0 tunneling protocol on this node, either as server or as
688     client. Support for this transport protocol is only available when gvpe
689     was compiled using the \f(CW\*(C`\-\-enable\-dns\*(C'\fR option.
690     .IP "enable-icmp = yes|true|on | no|false|off" 4
691     .IX Item "enable-icmp = yes|true|on | no|false|off"
692     See \fIgvpe.protocol\fR\|(7) for a description of the \s-1ICMP\s0 transport protocol.
693     .Sp
694     Enable the \s-1ICMP\s0 transport using \s-1ICMP\s0 packets of type \f(CW\*(C`icmp\-type\*(C'\fR on this
695     node.
696     .IP "enable-rawip = yes|true|on | no|false|off" 4
697     .IX Item "enable-rawip = yes|true|on | no|false|off"
698     See \fIgvpe.protocol\fR\|(7) for a description of the \s-1RAW\s0 \s-1IP\s0 transport protocol.
699     .Sp
700     Enable the \s-1RAW\s0 IPv4 transport using the \f(CW\*(C`ip\-proto\*(C'\fR protocol
701     (default: \f(CW\*(C`no\*(C'\fR).
702     .IP "enable-tcp = yes|true|on | no|false|off" 4
703     .IX Item "enable-tcp = yes|true|on | no|false|off"
704     See \fIgvpe.protocol\fR\|(7) for a description of the \s-1TCP\s0 transport protocol.
705     .Sp
706     Enable the TCPv4 transport using the \f(CW\*(C`tcp\-port\*(C'\fR port
707     (default: \f(CW\*(C`no\*(C'\fR). Support for this transport protocol is only available
708     when gvpe was compiled using the \f(CW\*(C`\-\-enable\-tcp\*(C'\fR option.
709     .IP "enable-udp = yes|true|on | no|false|off" 4
710     .IX Item "enable-udp = yes|true|on | no|false|off"
711     See \fIgvpe.protocol\fR\|(7) for a description of the \s-1UDP\s0 transport protocol.
712     .Sp
713     Enable the UDPv4 transport using the \f(CW\*(C`udp\-port\*(C'\fR port (default: \f(CW\*(C`no\*(C'\fR).
714     .IP "hostname = hostname | ip [can not be defaulted]" 4
715     .IX Item "hostname = hostname | ip [can not be defaulted]"
716     Forces the address of this node to be set to the given \s-1DNS\s0 hostname or \s-1IP\s0
717     address. It will be resolved before each connect request, so dyndns should
718     work fine. If this setting is not specified and a router is available,
719     then the router will be queried for the address of this node. Otherwise,
720     the connection attempt will fail.
721     .Sp
722     Note that \s-1DNS\s0 resolving is done synchronously, pausing the daemon. If that
723     is an issue you need to specify \s-1IP\s0 addresses.
724     .IP "icmp-type = integer" 4
725     .IX Item "icmp-type = integer"
726     Sets the type value to be used for outgoing (and incoming) packets sent
727     via the \s-1ICMP\s0 transport.
728     .Sp
729     The default is \f(CW0\fR (which is \f(CW\*(C`echo\-reply\*(C'\fR, also known as
730     \&\*(L"ping-reply\*(R"). Other useful values include \f(CW8\fR (\f(CW\*(C`echo\-request\*(C'\fR, a.k.a.
731     \&\*(L"ping\*(R") and \f(CW11\fR (\f(CW\*(C`time\-exceeded\*(C'\fR), but any 8\-bit value can be used.
732     .IP "if-up-data = value" 4
733     .IX Item "if-up-data = value"
734     The value specified using this directive will be passed to the \f(CW\*(C`if\-up\*(C'\fR
735     script in the environment variable \f(CW\*(C`IFUPDATA\*(C'\fR.
736     .IP "inherit-tos = yes|true|on | no|false|off" 4
737     .IX Item "inherit-tos = yes|true|on | no|false|off"
738     Whether to inherit the \s-1TOS\s0 settings of packets sent to the tunnel when
739     sending packets to this node (default: \f(CW\*(C`yes\*(C'\fR). If set to \f(CW\*(C`yes\*(C'\fR then
740     outgoing tunnel packets will have the same \s-1TOS\s0 setting as the packets sent
741     to the tunnel device, which is usually what you want.
742     .IP "max-retry = positive-number" 4
743     .IX Item "max-retry = positive-number"
744     The maximum interval in seconds (default: \f(CW3600\fR, one hour) between
745     retries to establish a connection to this node. When a connection cannot
746     be established, gvpe uses exponential back-off capped at this value. It's
747     sometimes useful to set this to a much lower value (e.g. \f(CW120\fR) on
748     connections to routers that usually are stable but sometimes are down, to
749     assure quick reconnections even after longer downtimes.
750     .IP "max-ttl = seconds" 4
751     .IX Item "max-ttl = seconds"
752     Expire packets that couldn't be sent after this many seconds
753     (default: \f(CW60\fR). Gvpe will normally queue packets for a node without an
754     active connection, in the hope of establishing a connection soon. This
755     value specifies the maximum lifetime a packet will stay in the queue, if a
756     packet gets older, it will be thrown away.
757     .IP "max-queue = positive\-number>=1" 4
758     .IX Item "max-queue = positive-number>=1"
759     The maximum number of packets that will be queued (default: \f(CW512\fR)
760     for this node. If more packets are sent then earlier packets will be
761     expired. See \f(CW\*(C`max\-ttl\*(C'\fR, above.
762     .IP "router-priority = 0 | 1 | positive\-number>=2" 4
763     .IX Item "router-priority = 0 | 1 | positive-number>=2"
764     Sets the router priority of the given node (default: \f(CW0\fR, disabled).
765     .Sp
766     If some node tries to connect to another node but it doesn't have a
767     hostname, it asks a router node for it's \s-1IP\s0 address. The router node
768     chosen is the one with the highest priority larger than \f(CW1\fR that is
769     currently reachable. This is called a \fImediated\fR connection, as the
770     connection itself will still be direct, but it uses another node to
771     mediate between the two nodes.
772     .Sp
773     The value \f(CW0\fR disables routing, that means if the node receives a packet
774     not for itself it will not forward it but instead drop it.
775     .Sp
776     The special value \f(CW1\fR allows other hosts to route through the router
777     host, but they will never route through it by default (i.e. the config
778     file of another node needs to specify a router priority higher than one
779     to choose such a node for routing).
780     .Sp
781     The idea behind this is that some hosts can, if required, bump the
782     \&\f(CW\*(C`router\-priority\*(C'\fR setting to higher than \f(CW1\fR in their local config to
783     route through specific hosts. If \f(CW\*(C`router\-priority\*(C'\fR is \f(CW0\fR, then routing
784     will be refused, so \f(CW1\fR serves as a \*(L"enable, but do not use by default\*(R"
785     switch.
786     .Sp
787     Nodes with \f(CW\*(C`router\-priority\*(C'\fR set to \f(CW2\fR or higher will always be forced
788     to \f(CW\*(C`connect\*(C'\fR = \f(CW\*(C`always\*(C'\fR (unless they are \f(CW\*(C`disabled\*(C'\fR).
789     .IP "tcp-port = port-number" 4
790     .IX Item "tcp-port = port-number"
791     Similar to \f(CW\*(C`udp\-port\*(C'\fR (default: \f(CW655\fR), but sets the \s-1TCP\s0 port number.
792     .IP "udp-port = port-number" 4
793     .IX Item "udp-port = port-number"
794     Sets the port number used by the \s-1UDP\s0 protocol (default: \f(CW655\fR, not
795     officially assigned by \s-1IANA\s0!).
796     .SH "CONFIG DIRECTORY LAYOUT"
797     .IX Header "CONFIG DIRECTORY LAYOUT"
798     The default (or recommended) directory layout for the config directory is:
799     .IP "gvpe.conf" 4
800     .IX Item "gvpe.conf"
801     The config file.
802     .IP "if-up" 4
803     .IX Item "if-up"
804     The if-up script
805     .IP "node-up, node-down" 4
806     .IX Item "node-up, node-down"
807     If used the node up or node-down scripts.
808     .IP "hostkey" 4
809     .IX Item "hostkey"
810     The (default path of the) private key of the current host.
811     .IP "pubkey/nodename" 4
812     .IX Item "pubkey/nodename"
813     The public keys of the other nodes, one file per node.
814     .SH "SEE ALSO"
815     .IX Header "SEE ALSO"
816     \&\fIgvpe\fR\|(5), \fIgvpe\fR\|(8), \fIgvpectrl\fR\|(8).
817     .SH "AUTHOR"
818     .IX Header "AUTHOR"
819     Marc Lehmann <gvpe@schmorp.de>