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Revision: 1.30
Committed: Tue Dec 4 10:29:43 2012 UTC (11 years, 5 months ago) by root
Branch: MAIN
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124     .\" ========================================================================
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126     .IX Title "GVPE.CONF 5"
127     .TH GVPE.CONF 5 "2012-07-06" "2.24" "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 \*(L"on\*(R" and \*(L"include\*(R" directives:
167     .IP "on nodename ..." 4
168     .IX Item "on nodename ..."
169     .PD 0
170     .IP "on !nodename ..." 4
171     .IX Item "on !nodename ..."
172     .PD
173     You can prefix any configuration directive with \f(CW\*(C`on\*(C'\fR and a nodename. \s-1GVPE\s0
174     will will only \*(L"execute\*(R" it on the named node, or (if the nodename starts
175     with \f(CW\*(C`!\*(C'\fR) on all nodes except the named one.
176     .Sp
177     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
178     \&\f(CW\*(C`branch1\*(C'\fR, and \f(CW\*(C`connect\*(C'\fR to \f(CW\*(C`ondemand\*(C'\fR everywhere but on branch2.
179     .Sp
180     .Vb 3
181     \& mtu = 1450
182     \& on branch1 loglevel = noise
183     \& on !branch2 connect = ondemand
184     .Ve
185     .IP "include relative-or-absolute-path" 4
186     .IX Item "include relative-or-absolute-path"
187     Reads the specified file (the path must not contain whitespace or \f(CW\*(C`=\*(C'\fR
188     characters) and evaluate all config directives in it as if they were
189     spelled out in place of the \f(CW\*(C`include\*(C'\fR directive.
190     .Sp
191     The path is a printf format string, that is, you must escape any \f(CW\*(C`%\*(C'\fR
192     by doubling it, and you can have a single \f(CW%s\fR inside, which will be
193     replaced by the current nodename.
194     .Sp
195     Relative paths are interpreted relative to the \s-1GVPE\s0 config directory.
196     .Sp
197     Example: include the file \fIlocal.conf\fR in the config directory on every
198     node.
199     .Sp
200     .Vb 1
201     \& include local.conf
202     .Ve
203     .Sp
204     Example: include a file \fIconf/\fRnodename\fI.conf\fR
205     .Sp
206     .Vb 1
207     \& include conf/%s.conf
208     .Ve
209     .SH "ANATOMY OF A CONFIG FILE"
210     .IX Header "ANATOMY OF A CONFIG FILE"
211     Usually, a config file starts with a few global settings (like the \s-1UDP\s0
212     port to listen on), followed by node-specific sections that begin with a
213     \&\f(CW\*(C`node = nickname\*(C'\fR line.
214     .PP
215     Every node that is part of the network must have a section that starts
216     with \f(CW\*(C`node = nickname\*(C'\fR. The number and order of the nodes is important
217     and must be the same on all nodes. It is not uncommon for node sections to
218     be completely empty \- if the default values are right.
219     .PP
220     Node-specific settings can be used at any time. If used before the first
221     node section they will set the default values for all following nodes.
222     .SH "CONFIG VARIABLES"
223     .IX Header "CONFIG VARIABLES"
224     .SS "\s-1GLOBAL\s0 \s-1SETTINGS\s0"
225     .IX Subsection "GLOBAL SETTINGS"
226     Global settings will affect the behaviour of the running gvpe daemon, that
227     is, they are in some sense node-specific (config files can set different
228     values on different nodes using \f(CW\*(C`on\*(C'\fR), but will affect the behaviour of
229     the gvpe daemon and all connections it creates.
230     .IP "dns-forw-host = hostname/ip" 4
231     .IX Item "dns-forw-host = hostname/ip"
232     The \s-1DNS\s0 server to forward \s-1DNS\s0 requests to for the \s-1DNS\s0 tunnel protocol
233     (default: \f(CW127.0.0.1\fR, changing it is highly recommended).
234     .IP "dns-forw-port = port-number" 4
235     .IX Item "dns-forw-port = port-number"
236     The port where the \f(CW\*(C`dns\-forw\-host\*(C'\fR is to be contacted (default: \f(CW53\fR,
237     which is fine in most cases).
238     .IP "dns-case-preserving = yes|true|on | no|false|off" 4
239     .IX Item "dns-case-preserving = yes|true|on | no|false|off"
240     Sets whether the \s-1DNS\s0 transport forwarding server preserves case (\s-1DNS\s0
241     servers have to, but some access systems are even more broken than others)
242     (default: true).
243     .Sp
244     Normally, when the forwarding server changes the case of domain names then
245     \&\s-1GVPE\s0 will automatically set this to false.
246     .IP "dns-max-outstanding = integer-number-of-requests" 4
247     .IX Item "dns-max-outstanding = integer-number-of-requests"
248     The maximum number of outstanding \s-1DNS\s0 transport requests
249     (default: \f(CW100\fR). \s-1GVPE\s0 will never issue more requests then the given
250     limit without receiving replies. In heavily overloaded situations it might
251     help to set this to a low number (e.g. \f(CW3\fR or even \f(CW1\fR) to limit the
252     number of parallel requests.
253     .Sp
254     The default should be working \s-1OK\s0 for most links.
255     .IP "dns-overlap-factor = float" 4
256     .IX Item "dns-overlap-factor = float"
257     The \s-1DNS\s0 transport uses the minimum request latency (\fBmin_latency\fR) seen
258     during a connection as it's timing base. This factor (default: \f(CW0.5\fR,
259     must be > 0) is multiplied by \fBmin_latency\fR to get the maximum sending
260     rate (= minimum send interval), i.e. a factor of \f(CW1\fR means that a new
261     request might be generated every \fBmin_latency\fR seconds, which means on
262     average there should only ever be one outstanding request. A factor of
263     \&\f(CW0.5\fR means that \s-1GVPE\s0 will send requests twice as often as the minimum
264     latency measured.
265     .Sp
266     For congested or picky \s-1DNS\s0 forwarders you could use a value nearer to or
267     exceeding \f(CW1\fR.
268     .Sp
269     The default should be working \s-1OK\s0 for most links.
270     .IP "dns-send-interval = send-interval-in-seconds" 4
271     .IX Item "dns-send-interval = send-interval-in-seconds"
272     The minimum send interval (= maximum rate) that the \s-1DNS\s0 transport will
273     use to send new \s-1DNS\s0 requests. \s-1GVPE\s0 will not exceed this rate even when
274     the latency is very low. The default is \f(CW0.01\fR, which means \s-1GVPE\s0 will
275     not send more than 100 \s-1DNS\s0 requests per connection per second. For
276     high-bandwidth links you could go lower, e.g. to \f(CW0.001\fR or so. For
277     congested or rate-limited links, you might want to go higher, say \f(CW0.1\fR,
278     \&\f(CW0.2\fR or even higher.
279     .Sp
280     The default should be working \s-1OK\s0 for most links.
281     .IP "dns-timeout-factor = float" 4
282     .IX Item "dns-timeout-factor = float"
283     Factor to multiply the \f(CW\*(C`min_latency\*(C'\fR (see \f(CW\*(C`dns\-overlap\-factor\*(C'\fR) by to
284     get request timeouts. The default of \f(CW8\fR means that the \s-1DNS\s0 transport
285     will resend the request when no reply has been received for longer than
286     eight times the minimum (= expected) latency, assuming the request or
287     reply has been lost.
288     .Sp
289     For congested links a higher value might be necessary (e.g. \f(CW30\fR). If
290     the link is very stable lower values (e.g. \f(CW2\fR) might work
291     nicely. Values near or below \f(CW1\fR makes no sense whatsoever.
292     .Sp
293     The default should be working \s-1OK\s0 for most links but will result in low
294     throughput if packet loss is high.
295     .IP "if-up = relative-or-absolute-path" 4
296     .IX Item "if-up = relative-or-absolute-path"
297     Sets the path of a script that should be called immediately after the
298     network interface is initialized (but not necessarily up). The following
299     environment variables are passed to it (the values are just examples).
300     .Sp
301     Variables that have the same value on all nodes:
302     .RS 4
303     .IP "CONFBASE=/etc/gvpe" 4
304     .IX Item "CONFBASE=/etc/gvpe"
305     The configuration base directory.
306     .IP "IFNAME=vpn0" 4
307     .IX Item "IFNAME=vpn0"
308     The network interface to initialize.
309     .IP "IFTYPE=native # or tincd" 4
310     .IX Item "IFTYPE=native # or tincd"
311     .PD 0
312     .IP "IFSUBTYPE=linux # or freebsd, darwin etc.." 4
313     .IX Item "IFSUBTYPE=linux # or freebsd, darwin etc.."
314     .PD
315     The interface type (\f(CW\*(C`native\*(C'\fR or \f(CW\*(C`tincd\*(C'\fR) and the subtype (usually the
316     \&\s-1OS\s0 name in lowercase) that this \s-1GVPE\s0 was configured for. Can be used to
317     select the correct syntax to use for network-related commands.
318     .IP "MTU=1436" 4
319     .IX Item "MTU=1436"
320     The \s-1MTU\s0 to set the interface to. You can use lower values (if done
321     consistently on all nodes), but this is usually either inefficient or
322     simply ineffective.
323     .IP "NODES=5" 4
324     .IX Item "NODES=5"
325     The number of nodes in this \s-1GVPE\s0 network.
326     .RE
327     .RS 4
328     .Sp
329     Variables that are node-specific and with values pertaining to the node
330     running this \s-1GVPE:\s0
331     .IP "IFUPDATA=string" 4
332     .IX Item "IFUPDATA=string"
333     The value of the configuration directive \f(CW\*(C`if\-up\-data\*(C'\fR.
334     .IP "MAC=fe:fd:80:00:00:01" 4
335     .IX Item "MAC=fe:fd:80:00:00:01"
336     The \s-1MAC\s0 address the network interface has to use.
337     .Sp
338     Might be used to initialize interfaces on platforms where \s-1GVPE\s0 does not
339     do this automatically. Please see the \f(CW\*(C`gvpe.osdep(5)\*(C'\fR man page for
340     platform-specific information.
341     .IP "NODENAME=branch1" 4
342     .IX Item "NODENAME=branch1"
343     The nickname of the node.
344     .IP "NODEID=1" 4
345     .IX Item "NODEID=1"
346     The numerical node \s-1ID\s0 of the node running this instance of \s-1GVPE\s0. The first
347     node mentioned in the config file gets \s-1ID\s0 1, the second \s-1ID\s0 2 and so on.
348     .RE
349     .RS 4
350     .Sp
351     In addition, all node-specific variables (except \f(CW\*(C`NODEID\*(C'\fR) will be
352     available with a postfix of \f(CW\*(C`_nodeid\*(C'\fR, which contains the value for that
353     node, e.g. the \f(CW\*(C`MAC_1\*(C'\fR variable contains the \s-1MAC\s0 address of node #1, while
354     the \f(CW\*(C`NODENAME_22\*(C'\fR variable contains the name of node #22.
355     .Sp
356     Here is a simple if-up script:
357     .Sp
358     .Vb 5
359     \& #!/bin/sh
360     \& ip link set $IFNAME up
361     \& [ $NODENAME = branch1 ] && ip addr add 10.0.0.1 dev $IFNAME
362     \& [ $NODENAME = branch2 ] && ip addr add 10.1.0.1 dev $IFNAME
363     \& ip route add 10.0.0.0/8 dev $IFNAME
364     .Ve
365     .Sp
366     More complicated examples (using routing to reduce \s-1ARP\s0 traffic) can be
367     found in the \fIetc/\fR subdirectory of the distribution.
368     .RE
369     .IP "ifname = devname" 4
370     .IX Item "ifname = devname"
371     Sets the tun interface name to the given name. The default is OS-specific
372     and most probably something like \f(CW\*(C`tun0\*(C'\fR.
373     .IP "ifpersist = yes|true|on | no|false|off" 4
374     .IX Item "ifpersist = yes|true|on | no|false|off"
375     Should the tun/tap device be made persistent, that is, should the device
376     stay up even when gvpe exits? Some versions of the tunnel device have
377     problems sending packets when gvpe is restarted in persistent mode, so
378     if the connections can be established but you cannot send packets from
379     the local node, try to set this to \f(CW\*(C`off\*(C'\fR and do an ifconfig down on the
380     device.
381     .IP "ip-proto = numerical-ip-protocol" 4
382     .IX Item "ip-proto = numerical-ip-protocol"
383     Sets the protocol number to be used for the rawip protocol. This is a
384     global option because all nodes must use the same protocol, and since
385     there are no port numbers, you cannot easily run more than one gvpe
386     instance using the same protocol, nor can you share the protocol with
387     other programs.
388     .Sp
389     The default is 47 (\s-1GRE\s0), which has a good chance of tunneling
390     through firewalls (but note that gvpe's rawip protocol is not \s-1GRE\s0
391     compatible). Other common choices are 50 (\s-1IPSEC\s0, \s-1ESP\s0), 51 (\s-1IPSEC\s0, \s-1AH\s0), 4
392     (\s-1IPIP\s0 tunnels) or 98 (\s-1ENCAP\s0, rfc1241).
393     .Sp
394     Many versions of Linux seem to have a bug that causes them to reorder
395     packets for some ip protocols (\s-1GRE\s0, \s-1ESP\s0) but not for others (\s-1AH\s0), so
396     choose wisely (that is, use 51, \s-1AH\s0).
397     .IP "http-proxy-host = hostname/ip" 4
398     .IX Item "http-proxy-host = hostname/ip"
399     The \f(CW\*(C`http\-proxy\-*\*(C'\fR family of options are only available if gvpe was
400     compiled with the \f(CW\*(C`\-\-enable\-http\-proxy\*(C'\fR option and enable tunneling of
401     tcp connections through a http proxy server.
402     .Sp
403     \&\f(CW\*(C`http\-proxy\-host\*(C'\fR and \f(CW\*(C`http\-proxy\-port\*(C'\fR should specify the hostname and
404     port number of the proxy server. See \f(CW\*(C`http\-proxy\-loginpw\*(C'\fR if your proxy
405     requires authentication.
406     .Sp
407     Please note that gvpe will still try to resolve all hostnames in the
408     configuration file, so if you are behind a proxy without access to a \s-1DNS\s0
409     server better use numerical \s-1IP\s0 addresses.
410     .Sp
411     To make best use of this option disable all protocols except \s-1TCP\s0 in your
412     config file and make sure your routers (or all other nodes) are listening
413     on a port that the proxy allows (443, https, is a common choice).
414     .Sp
415     If you have a router, connecting to it will suffice. Otherwise \s-1TCP\s0 must be
416     enabled on all nodes.
417     .Sp
418     Example:
419     .Sp
420     .Vb 3
421     \& http\-proxy\-host = proxy.example.com
422     \& http\-proxy\-port = 3128 # 8080 is another common choice
423     \& http\-proxy\-auth = schmorp:grumbeere
424     .Ve
425     .IP "http-proxy-port = proxy-tcp-port" 4
426     .IX Item "http-proxy-port = proxy-tcp-port"
427     The port where your proxy server listens.
428     .IP "http-proxy-auth = login:password" 4
429     .IX Item "http-proxy-auth = login:password"
430     The optional login and password used to authenticate to the proxy server,
431     separated by a literal colon (\f(CW\*(C`:\*(C'\fR). Only basic authentication is
432     currently supported.
433     .IP "keepalive = seconds" 4
434     .IX Item "keepalive = seconds"
435     Sets the keepalive probe interval in seconds (default: \f(CW60\fR). After this
436     many seconds of inactivity the daemon will start to send keepalive probe
437     every 3 seconds until it receives a reply from the other end. If no reply
438     is received within 15 seconds, the peer is considered unreachable and the
439     connection is closed.
440     .IP "loglevel = noise|trace|debug|info|notice|warn|error|critical" 4
441     .IX Item "loglevel = noise|trace|debug|info|notice|warn|error|critical"
442     Set the logging level. Connection established messages are logged at level
443     \&\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.
444     .IP "mtu = bytes" 4
445     .IX Item "mtu = bytes"
446     Sets the maximum \s-1MTU\s0 that should be used on outgoing packets (basically
447     the \s-1MTU\s0 of the outgoing interface) The daemon will automatically calculate
448     maximum overhead (e.g. \s-1UDP\s0 header size, encryption blocksize...) and pass
449     this information to the \f(CW\*(C`if\-up\*(C'\fR script.
450     .Sp
451     Recommended values are 1500 (ethernet), 1492 (pppoe), 1472 (pptp).
452     .Sp
453     This value must be the minimum of the \s-1MTU\s0 values of all nodes.
454     .IP "node = nickname" 4
455     .IX Item "node = nickname"
456     Not really a config setting but introduces a node section. The nickname is
457     used to select the right configuration section and must be passed as an
458     argument to the gvpe daemon.
459     .IP "node-up = relative-or-absolute-path" 4
460     .IX Item "node-up = relative-or-absolute-path"
461     Sets a command (default: none) that should be called whenever a connection
462     is established (even on rekeying operations). Note that node\-up/down
463     scripts will be run asynchronously, but execution is serialised, so there
464     will only ever be one such script running.
465     .Sp
466     In addition to all the variables passed to \f(CW\*(C`if\-up\*(C'\fR scripts, the following
467     environment variables will be set (values are just examples):
468     .RS 4
469     .IP "DESTNODE=branch2" 4
470     .IX Item "DESTNODE=branch2"
471     The name of the remote node.
472     .IP "DESTID=2" 4
473     .IX Item "DESTID=2"
474     The node id of the remote node.
475     .IP "DESTSI=rawip/88.99.77.55:0" 4
476     .IX Item "DESTSI=rawip/88.99.77.55:0"
477     The \*(L"socket info\*(R" of the target node, protocol dependent but usually in
478     the format protocol/ip:port.
479     .IP "DESTIP=188.13.66.8" 4
480     .IX Item "DESTIP=188.13.66.8"
481     The numerical \s-1IP\s0 address of the remote node (gvpe accepts connections from
482     everywhere, as long as the other node can authenticate itself).
483     .IP "DESTPORT=655 # deprecated" 4
484     .IX Item "DESTPORT=655 # deprecated"
485     The protocol port used by the other side, if applicable.
486     .IP "STATE=up" 4
487     .IX Item "STATE=up"
488     Node-up scripts get called with STATE=up, node-change scripts get called
489     with STATE=change and node-down scripts get called with STATE=down.
490     .RE
491     .RS 4
492     .Sp
493     Here is a nontrivial example that uses nsupdate to update the name => ip
494     mapping in some \s-1DNS\s0 zone:
495     .Sp
496     .Vb 6
497     \& #!/bin/sh
498     \& {
499     \& echo update delete $DESTNODE.lowttl.example.net. a
500     \& echo update add $DESTNODE.lowttl.example.net. 1 in a $DESTIP
501     \& echo
502     \& } | nsupdate \-d \-k $CONFBASE:key.example.net.
503     .Ve
504     .RE
505     .IP "node-change = relative-or-absolute-path" 4
506     .IX Item "node-change = relative-or-absolute-path"
507     Same as \f(CW\*(C`node\-change\*(C'\fR, but gets called whenever something about a
508     connection changes (such as the source \s-1IP\s0 address).
509     .IP "node-down = relative-or-absolute-path" 4
510     .IX Item "node-down = relative-or-absolute-path"
511     Same as \f(CW\*(C`node\-up\*(C'\fR, but gets called whenever a connection is lost.
512     .IP "pid-file = path" 4
513     .IX Item "pid-file = path"
514     The path to the pid file to check and create
515     (default: \f(CW\*(C`LOCALSTATEDIR/run/gvpe.pid\*(C'\fR).
516     .IP "private-key = relative-path-to-key" 4
517     .IX Item "private-key = relative-path-to-key"
518     Sets the path (relative to the config directory) to the private key
519     (default: \f(CW\*(C`hostkey\*(C'\fR). This is a printf format string so every \f(CW\*(C`%\*(C'\fR must
520     be doubled. A single \f(CW%s\fR is replaced by the hostname, so you could
521     use paths like \f(CW\*(C`hostkeys/%s\*(C'\fR to fetch the files at the location where
522     \&\f(CW\*(C`gvpectrl\*(C'\fR puts them.
523     .Sp
524     Since only the private key file of the current node is used and the
525     private key file should be kept secret per-node to avoid spoofing, it is
526     not recommended to use this feature.
527     .IP "rekey = seconds" 4
528     .IX Item "rekey = seconds"
529     Sets the rekeying interval in seconds (default: \f(CW3600\fR). Connections are
530     reestablished every \f(CW\*(C`rekey\*(C'\fR seconds, making them use a new encryption
531     key.
532     .IP "nfmark = integer" 4
533     .IX Item "nfmark = integer"
534     This advanced option, when set to a nonzero value (default: \f(CW0\fR), tries
535     to set the netfilter mark (or fwmark) value on all sockets gvpe uses to
536     send packets.
537     .Sp
538     This can be used to make gvpe use a different set of routing rules. For
539     example, on GNU/Linux, the \f(CW\*(C`if\-up\*(C'\fR could set \f(CW\*(C`nfmark\*(C'\fR to 1000 and then
540     put all routing rules into table \f(CW99\fR and then use an ip rule to make
541     gvpe traffic avoid that routing table, in effect routing normal traffic
542     via gvpe and gvpe traffic via the normal system routing tables:
543     .Sp
544     .Vb 1
545     \& ip rule add not fwmark 1000 lookup 99
546     .Ve
547     .SS "\s-1NODE\s0 \s-1SPECIFIC\s0 \s-1SETTINGS\s0"
548     .IX Subsection "NODE SPECIFIC SETTINGS"
549     The following settings are node-specific, that is, every node can have
550     different settings, even within the same gvpe instance. Settings that are
551     set before the first node section set the defaults, settings that are
552     set within a node section only apply to the given node.
553     .IP "allow-direct = nodename" 4
554     .IX Item "allow-direct = nodename"
555     Allow direct connections to this node. See \f(CW\*(C`deny\-direct\*(C'\fR for more info.
556     .IP "compress = yes|true|on | no|false|off" 4
557     .IX Item "compress = yes|true|on | no|false|off"
558     For the current node, this specified whether it will accept compressed
559     packets, and for all other nodes, this specifies whether to try to
560     compress data packets sent to this node (default: \f(CW\*(C`yes\*(C'\fR). Compression is
561     really cheap even on slow computers, has no size overhead at all and will
562     only be used when the other side supports compression, so enabling this is
563     often a good idea.
564     .IP "connect = ondemand | never | always | disabled" 4
565     .IX Item "connect = ondemand | never | always | disabled"
566     Sets the connect mode (default: \f(CW\*(C`always\*(C'\fR). It can be \f(CW\*(C`always\*(C'\fR (always
567     try to establish and keep a connection to the given node), \f(CW\*(C`never\*(C'\fR
568     (never initiate a connection to the given host, but accept connections),
569     \&\f(CW\*(C`ondemand\*(C'\fR (try to establish a connection when there are outstanding
570     packets in the queue and take it down after the keepalive interval) or
571     \&\f(CW\*(C`disabled\*(C'\fR (node is bad, don't talk to it).
572     .Sp
573     Routers will automatically be forced to \f(CW\*(C`always\*(C'\fR unless they are
574     \&\f(CW\*(C`disabled\*(C'\fR, to ensure all nodes can talk to each other.
575     .IP "deny-direct = nodename | *" 4
576     .IX Item "deny-direct = nodename | *"
577     Deny direct connections to the specified node (or all nodes when \f(CW\*(C`*\*(C'\fR
578     is given). Only one node can be specified, but you can use multiple
579     \&\f(CW\*(C`allow\-direct\*(C'\fR and \f(CW\*(C`deny\-direct\*(C'\fR statements. This only makes sense in
580     networks with routers, as routers are required for indirect connections.
581     .Sp
582     Sometimes, a node cannot reach some other nodes for reasons of network
583     connectivity. For example, a node behind a firewall that only allows
584     connections to/from a single other node in the network. In this case one
585     should specify \f(CW\*(C`deny\-direct = *\*(C'\fR and \f(CW\*(C`allow\-direct = othernodename\*(C'\fR (the other
586     node \fImust\fR be a router for this to work).
587     .Sp
588     The algorithm to check whether a connection may be direct is as follows:
589     .Sp
590     1. Other node mentioned in an \f(CW\*(C`allow\-direct\*(C'\fR? If yes, allow the connection.
591     .Sp
592     2. Other node mentioned in a \f(CW\*(C`deny\-direct\*(C'\fR? If yes, deny direct connections.
593     .Sp
594     3. Allow the connection.
595     .Sp
596     That is, \f(CW\*(C`allow\-direct\*(C'\fR takes precedence over \f(CW\*(C`deny\-direct\*(C'\fR.
597     .Sp
598     The check is done in both directions, i.e. both nodes must allow a direct
599     connection before one is attempted, so you only need to specify connect
600     limitations on one node.
601     .IP "dns-domain = domain-suffix" 4
602     .IX Item "dns-domain = domain-suffix"
603     The \s-1DNS\s0 domain suffix that points to the \s-1DNS\s0 tunnel server for this node.
604     .Sp
605     The domain must point to a \s-1NS\s0 record that points to the \fIdns-hostname\fR,
606     i.e.
607     .Sp
608     .Vb 2
609     \& dns\-domainname = tunnel.example.net
610     \& dns\-hostname = tunnel\-server.example.net
611     .Ve
612     .Sp
613     Corresponds to the following \s-1DNS\s0 entries in the \f(CW\*(C`example.net\*(C'\fR domain:
614     .Sp
615     .Vb 2
616     \& tunnel.example.net. NS tunnel\-server.example.net.
617     \& tunnel\-server.example.net. A 13.13.13.13
618     .Ve
619     .IP "dns-hostname = hostname/ip" 4
620     .IX Item "dns-hostname = hostname/ip"
621     The address to bind the \s-1DNS\s0 tunnel socket to, similar to the \f(CW\*(C`hostname\*(C'\fR,
622     but for the \s-1DNS\s0 tunnel protocol only. Default: \f(CW0.0.0.0\fR, but that might
623     change.
624     .IP "dns-port = port-number" 4
625     .IX Item "dns-port = port-number"
626     The port to bind the \s-1DNS\s0 tunnel socket to. Must be \f(CW53\fR on \s-1DNS\s0 tunnel servers.
627     .IP "enable-dns = yes|true|on | no|false|off" 4
628     .IX Item "enable-dns = yes|true|on | no|false|off"
629     See \fIgvpe.protocol\fR\|(7) for a description of the \s-1DNS\s0 transport
630     protocol. Avoid this protocol if you can.
631     .Sp
632     Enable the \s-1DNS\s0 tunneling protocol on this node, either as server or as
633     client. Support for this transport protocol is only available when gvpe
634     was compiled using the \f(CW\*(C`\-\-enable\-dns\*(C'\fR option.
635     .IP "enable-icmp = yes|true|on | no|false|off" 4
636     .IX Item "enable-icmp = yes|true|on | no|false|off"
637     See \fIgvpe.protocol\fR\|(7) for a description of the \s-1ICMP\s0 transport protocol.
638     .Sp
639     Enable the \s-1ICMP\s0 transport using \s-1ICMP\s0 packets of type \f(CW\*(C`icmp\-type\*(C'\fR on this
640     node.
641     .IP "enable-rawip = yes|true|on | no|false|off" 4
642     .IX Item "enable-rawip = yes|true|on | no|false|off"
643     See \fIgvpe.protocol\fR\|(7) for a description of the \s-1RAW\s0 \s-1IP\s0 transport protocol.
644     .Sp
645     Enable the \s-1RAW\s0 IPv4 transport using the \f(CW\*(C`ip\-proto\*(C'\fR protocol
646     (default: \f(CW\*(C`no\*(C'\fR).
647     .IP "enable-tcp = yes|true|on | no|false|off" 4
648     .IX Item "enable-tcp = yes|true|on | no|false|off"
649     See \fIgvpe.protocol\fR\|(7) for a description of the \s-1TCP\s0 transport protocol.
650     .Sp
651     Enable the TCPv4 transport using the \f(CW\*(C`tcp\-port\*(C'\fR port
652     (default: \f(CW\*(C`no\*(C'\fR). Support for this transport protocol is only available
653     when gvpe was compiled using the \f(CW\*(C`\-\-enable\-tcp\*(C'\fR option.
654     .IP "enable-udp = yes|true|on | no|false|off" 4
655     .IX Item "enable-udp = yes|true|on | no|false|off"
656     See \fIgvpe.protocol\fR\|(7) for a description of the \s-1UDP\s0 transport protocol.
657     .Sp
658     Enable the UDPv4 transport using the \f(CW\*(C`udp\-port\*(C'\fR port (default: \f(CW\*(C`no\*(C'\fR).
659     .IP "hostname = hostname | ip [can not be defaulted]" 4
660     .IX Item "hostname = hostname | ip [can not be defaulted]"
661     Forces the address of this node to be set to the given \s-1DNS\s0 hostname or \s-1IP\s0
662     address. It will be resolved before each connect request, so dyndns should
663     work fine. If this setting is not specified and a router is available,
664     then the router will be queried for the address of this node. Otherwise,
665     the connection attempt will fail.
666     .Sp
667     Note that \s-1DNS\s0 resolving is done synchronously, pausing the daemon. If that
668     is an issue you need to specify \s-1IP\s0 addresses.
669     .IP "icmp-type = integer" 4
670     .IX Item "icmp-type = integer"
671     Sets the type value to be used for outgoing (and incoming) packets sent
672     via the \s-1ICMP\s0 transport.
673     .Sp
674     The default is \f(CW0\fR (which is \f(CW\*(C`echo\-reply\*(C'\fR, also known as
675     \&\*(L"ping-reply\*(R"). Other useful values include \f(CW8\fR (\f(CW\*(C`echo\-request\*(C'\fR, a.k.a.
676     \&\*(L"ping\*(R") and \f(CW11\fR (\f(CW\*(C`time\-exceeded\*(C'\fR), but any 8\-bit value can be used.
677     .IP "if-up-data = value" 4
678     .IX Item "if-up-data = value"
679     The value specified using this directive will be passed to the \f(CW\*(C`if\-up\*(C'\fR
680     script in the environment variable \f(CW\*(C`IFUPDATA\*(C'\fR.
681     .IP "inherit-tos = yes|true|on | no|false|off" 4
682     .IX Item "inherit-tos = yes|true|on | no|false|off"
683     Whether to inherit the \s-1TOS\s0 settings of packets sent to the tunnel when
684     sending packets to this node (default: \f(CW\*(C`yes\*(C'\fR). If set to \f(CW\*(C`yes\*(C'\fR then
685     outgoing tunnel packets will have the same \s-1TOS\s0 setting as the packets sent
686     to the tunnel device, which is usually what you want.
687     .IP "max-retry = positive-number" 4
688     .IX Item "max-retry = positive-number"
689     The maximum interval in seconds (default: \f(CW3600\fR, one hour) between
690     retries to establish a connection to this node. When a connection cannot
691     be established, gvpe uses exponential back-off capped at this value. It's
692     sometimes useful to set this to a much lower value (e.g. \f(CW120\fR) on
693     connections to routers that usually are stable but sometimes are down, to
694     assure quick reconnections even after longer downtimes.
695     .IP "max-ttl = seconds" 4
696     .IX Item "max-ttl = seconds"
697     Expire packets that couldn't be sent after this many seconds
698     (default: \f(CW60\fR). Gvpe will normally queue packets for a node without an
699     active connection, in the hope of establishing a connection soon. This
700     value specifies the maximum lifetime a packet will stay in the queue, if a
701     packet gets older, it will be thrown away.
702     .IP "max-queue = positive\-number>=1" 4
703     .IX Item "max-queue = positive-number>=1"
704     The maximum number of packets that will be queued (default: \f(CW512\fR)
705     for this node. If more packets are sent then earlier packets will be
706     expired. See \f(CW\*(C`max\-ttl\*(C'\fR, above.
707     .IP "router-priority = 0 | 1 | positive\-number>=2" 4
708     .IX Item "router-priority = 0 | 1 | positive-number>=2"
709     Sets the router priority of the given node (default: \f(CW0\fR, disabled).
710     .Sp
711     If some node tries to connect to another node but it doesn't have a
712     hostname, it asks a router node for it's \s-1IP\s0 address. The router node
713     chosen is the one with the highest priority larger than \f(CW1\fR that is
714     currently reachable. This is called a \fImediated\fR connection, as the
715     connection itself will still be direct, but it uses another node to
716     mediate between the two nodes.
717     .Sp
718     The value \f(CW0\fR disables routing, that means if the node receives a packet
719     not for itself it will not forward it but instead drop it.
720     .Sp
721     The special value \f(CW1\fR allows other hosts to route through the router
722     host, but they will never route through it by default (i.e. the config
723     file of another node needs to specify a router priority higher than one
724     to choose such a node for routing).
725     .Sp
726     The idea behind this is that some hosts can, if required, bump the
727     \&\f(CW\*(C`router\-priority\*(C'\fR setting to higher than \f(CW1\fR in their local config to
728     route through specific hosts. If \f(CW\*(C`router\-priority\*(C'\fR is \f(CW0\fR, then routing
729     will be refused, so \f(CW1\fR serves as a \*(L"enable, but do not use by default\*(R"
730     switch.
731     .Sp
732     Nodes with \f(CW\*(C`router\-priority\*(C'\fR set to \f(CW2\fR or higher will always be forced
733     to \f(CW\*(C`connect\*(C'\fR = \f(CW\*(C`always\*(C'\fR (unless they are \f(CW\*(C`disabled\*(C'\fR).
734     .IP "tcp-port = port-number" 4
735     .IX Item "tcp-port = port-number"
736     Similar to \f(CW\*(C`udp\-port\*(C'\fR (default: \f(CW655\fR), but sets the \s-1TCP\s0 port number.
737     .IP "udp-port = port-number" 4
738     .IX Item "udp-port = port-number"
739     Sets the port number used by the \s-1UDP\s0 protocol (default: \f(CW655\fR, not
740     officially assigned by \s-1IANA\s0!).
741     .SH "CONFIG DIRECTORY LAYOUT"
742     .IX Header "CONFIG DIRECTORY LAYOUT"
743     The default (or recommended) directory layout for the config directory is:
744     .IP "gvpe.conf" 4
745     .IX Item "gvpe.conf"
746     The config file.
747     .IP "if-up" 4
748     .IX Item "if-up"
749     The if-up script
750     .IP "node-up, node-down" 4
751     .IX Item "node-up, node-down"
752     If used the node up or node-down scripts.
753     .IP "hostkey" 4
754     .IX Item "hostkey"
755     The private key (taken from \f(CW\*(C`hostkeys/nodename\*(C'\fR) of the current host.
756     .IP "pubkey/nodename" 4
757     .IX Item "pubkey/nodename"
758     The public keys of the other nodes, one file per node.
759     .SH "SEE ALSO"
760     .IX Header "SEE ALSO"
761     \&\fIgvpe\fR\|(5), \fIgvpe\fR\|(8), \fIgvpectrl\fR\|(8).
762     .SH "AUTHOR"
763     .IX Header "AUTHOR"
764     Marc Lehmann <gvpe@schmorp.de>