gvpe/doc/gvpe.conf.5.pod

=head1 NAME

gvpe.conf - configuration file for the GNU VPE daemon

=head1 SYNOPSIS

   udp-port = 407
   mtu = 1492
   ifname = vpn0

   node = branch1
   hostname = 1.2.3.4

   node = branch2
   hostname = www.example.net
   udp-port = 500       # this host uses a different udp-port

   node = branch3
   connect = ondemand

=head1 DESCRIPTION

The gvpe config file consists of a series of lines that contain C<variable
= value> pairs. Empty lines are ignored. Comments start with a C<#> and
extend to the end of the line. They can be used on their own lines, or
after any directives. Spaces are allowed before or after the C<=> sign or
after values, but not within the variable names or values themselves.

The only exception to the above is the "on" directive that can prefix any
C<name = value> setting and will only "execute" it on the named node, or
(if the nodename starts with "!") on all nodes except the named one.

   name = value
   on branch1 loglevel = noise
   on !branch2 connect = ondemand

All settings are executed "in order", that is, later settings of the same
variable overwrite earlier ones.

=head1 ANATOMY OF A CONFIG FILE

Usually, a config file starts with global settings (like the udp port to
listen on), followed by node-specific sections that begin with a C<node =
nickname> line.

Every node that is part of the network must have a section that starts
with C<node = nickname>. The number and order of the nodes is important
and must be the same on all hosts. It is not uncommon for node sections to
be completely empty - if the default values are right.

Node-specific settings can be used at any time. If used before the first
node section they will set the default values for all following nodes.

=head1 CONFIG VARIABLES

=head2 GLOBAL SETTINGS

Global settings will affect the behaviour of the running gvpe daemon, that
is, they are in some sense node-specific (config files can set different
values on different nodes using C<on>), but will affect the behaviour of
the gvpe daemon and all connections it creates.

=over 4

=item dns-forw-host = hostname/ip

The dns server to forward dns requests to for the DNS tunnel protocol
(default: C<127.0.0.1>, changing it is highly recommended).

=item dns-forw-port = port-number

The port where the C<dns-forw-host> is to be contacted (default: C<53>,
which is fine in most cases).

=item if-up = relative-or-absolute-path

Sets the path of a script that should be called immediately after the
network interface is initialized (but not neccessarily up). The following
environment variables are passed to it (the values are just examples):

=over 4

=item CONFBASE=/etc/gvpe

The configuration base directory.

=item IFNAME=vpn0

The interface to initialize.

=item MTU=1436

The MTU to set the interface to. You can use lower values (if done
consistently on all hosts), but this is usually ineffective.

=item MAC=fe:fd:80:00:00:01

The MAC address to set the interface to. The script *must* set the
interface MAC to this value. You will most likely use one of these:

   ip link set $IFNAME address $MAC mtu $MTU up # GNU/Linux
   ifconfig $IFNAME ether $MAC mtu $MTU up      # FreeBSD

Please see the C<gvpe.osdep(5)> manpage for platform-specific information.

=item IFTYPE=native # or tincd

=item IFSUBTYPE=linux # or freebsd, darwin etc..

The interface type (C<native> or C<tincd>) and the subtype (usually the os
name in lowercase) that this gvpe was configured for. Can be used to select
the correct syntax to use for network-related commands.

=item NODENAME=branch1

The nickname of the current node, as passed to the gvpe daemon.

=item NODEID=1

The numerical node id of the current node. The first node mentioned in the
config file gets ID 1, the second ID 2 and so on.

=back

Here is a simple if-up script:

   #!/bin/sh
   ip link set $IFNAME address $MAC mtu $MTU up
   [ $NODENAME = branch1 ] && ip addr add 10.0.0.1 dev $IFNAME
   [ $NODENAME = branch2 ] && ip addr add 10.1.0.1 dev $IFNAME
   ip route add 10.0.0.0/8 dev $IFNAME

More complicated examples (using routing to reduce arp traffic) can be
found in the etc/ subdirectory of the distribution.

=item ifname = devname

Sets the tun interface name to the given name. The default is OS-specific
and most probably something like C<tun0>.

=item ifpersist = yes|true|on | no|false|off

Should the tun/tap device be made persistent, that is, should the device
stay up even when gvpe exits? Some versions of the tunnel device have
problems sending packets when gvpe is restarted in persistent mode, so
if the connections can be established but you cannot send packets from
the local node, try to set this to C<off> and do an ifconfig down on the
device.

=item ip-proto = numerical-ip-protocol

Sets the protocol number to be used for the rawip protocol. This is a
global option because all hosts must use the same protocol, and since
there are no port numbers, you cannot easily run more than one gvpe
instance using the same protocol, nor can you share the protocol with
other programs.

The default is 47 (GRE), which has a good chance of tunneling through
firewalls (but note that the rawip protocol is not GRE compatible). Other
common choices are 50 (IPSEC, ESP), 51 (IPSEC, AH), 4 (IPIP tunnels) or 98
(ENCAP, rfc1241)

=item http-proxy-host = hostname/ip

The C<http-proxy-*> family of options are only available if gvpe was
compiled with the C<--enable-http-proxy> option and enable tunneling of
tcp connections through a http proxy server.

C<http-proxy-host> and C<http-proxy-port> should specify the hostname and
port number of the proxy server. See C<http-proxy-loginpw> if your proxy
requires authentication.

Please note that gvpe will still try to resolve all hostnames in the
configuration file, so if you are behind a proxy without access to a dns
server better use numerical IP addresses.

To make best use of this option disable all protocols except tcp in your
config file and make sure your routers (or all other hosts) are listening
on a port that the proxy allows (443, https, is a common choice).

If you have a router, connecting to it will suffice. Otherwise tcp must be
enabled on all hosts.

Example:

   http-proxy-host = proxy.example.com
   http-proxy-port = 3128       # 8080 is another common choice
   http-proxy-auth = schmorp:grumbeere

=item http-proxy-port = proxy-tcp-port

The port where your proxy server listens.

=item http-proxy-auth = login:password

The optional login and password used to authenticate to the proxy server,
seperated by a literal colon (C<:>). Only basic authentication is
currently supported.

=item keepalive = seconds

Sets the keepalive probe interval in seconds (default: C<60>). After this
many seconds of inactivity the daemon will start to send keepalive probe
every 5 seconds until it receives a reply from the other end.  If no reply
is received within 30 seconds, the peer is considered unreachable and the
connection is closed.

=item loglevel = noise|trace|debug|info|notice|warn|error|critical

Set the logging level. Connection established messages are logged at level
C<info>, notable errors are logged with C<error>. Default is C<info>.

=item mtu = bytes

Sets the maximum MTU that should be used on outgoing packets (basically
the MTU of the outgoing interface) The daemon will automatically calculate
maximum overhead (e.g. udp header size, encryption blocksize...) and pass
this information to the C<if-up> script.

Recommended values are 1500 (ethernet), 1492 (pppoe), 1472 (pptp).

This value must be the minimum of the mtu values of all hosts.

=item node = nickname

Not really a config setting but introduces a node section. The nickname is
used to select the right configuration section and must be passed as an
argument to the gvpe daemon.

=item node-up = relative-or-absolute-path

Sets a command (default: no script) that should be called whenever a
connection is established (even on rekeying operations). In addition
to the variables passed to C<if-up> scripts, the following environment
variables will be set:

=over 4

=item DESTNODE=branch2

The name of the remote node.

=item DESTID=2

The node id of the remote node.

=item DESTIP=188.13.66.8

The numerical IP address of the remote host (gvpe accepts connections from
everywhere, as long as the other host can authenticate itself).

=item DESTPORT=655 # deprecated

The UDP port used by the other side.

=item STATE=UP

Node-up scripts get called with STATE=UP, node-down scripts get called
with STATE=DOWN.

=back

Here is a nontrivial example that uses nsupdate to update the name => ip
mapping in some dns zone:

   #!/bin/sh
   {
     echo update delete $DESTNODE.lowttl.example.net. a
     echo update add $DESTNODE.lowttl.example.net. 1 in a $DESTIP
     echo   
   } | nsupdate -d -k $CONFBASE:key.example.net.

=item node-down = relative-or-absolute-path

Same as C<node-up>, but gets called whenever a connection is lost.

=item pid-file = path

The path to the pid file to check and create
(default: C<LOCALSTATEDIR/run/gvpe.pid>).

=item private-key = relative-path-to-key

Sets the path (relative to the config directory) to the private key
(default: C<hostkey>). This is a printf format string so every C<%> must
be doubled. A single C<%s> is replaced by the hostname, so you could
use paths like C<hostkeys/%s> to fetch the files at the location where
C<gvpectrl> puts them.

Since only the private key file of the current node is used and the
private key file should be kept secret per-host to avoid spoofings, it is
not recommended to use this feature.

=item rekey = seconds

Sets the rekeying interval in seconds (default: C<3600>). Connections are
reestablished every C<rekey> seconds.

=back

=head2 NODE SPECIFIC SETTINGS

The following settings are node-specific, that is, every node can have
different settings, even within the same gvpe instance. Settings that are
executed before the first node section set the defaults, settings that are
executed within a node section only apply to the given node.

=over 4

=item compress = yes|true|on | no|false|off

Wether to compress data packets sent to this host (default: C<yes>).
Compression is really cheap even on slow computers and has no size
overhead at all, so enabling this is a good idea.

=item connect = ondemand | never | always | disabled

Sets the connect mode (default: C<always>). It can be C<always> (always
try to establish and keep a connection to the given host), C<never>
(never initiate a connection to the given host, but accept connections),
C<ondemand> (try to establish a connection on the first packet sent, and
take it down after the keepalive interval) or C<disabled> (node is bad,
don't talk to it).

=item dns-domain = domain-suffix

The DNS domain suffix that points to the DNS tunnel server for this node.

The domain must point to a NS record that points to the I<dns-hostname>,
i.e.

   dns-domainname = tunnel.example.net
   dns-hostname   = tunnel-server.example.net

Corresponds to the following DNS entries in the C<example.net> domain:

   tunnel.example.net.         NS tunnel-server.example.net.
   tunnel-server.example.net.  A  13.13.13.13

=item dns-hostname = hostname/ip

The address to bind the DNS tunnel socket to, similar to the C<hostname>,
but for the DNS tunnel protocol only. Default: C<0.0.0.0>, but that might
change.

=item dns-port = port-number

The port to bind the DNS tunnel socket to. Must be C<53> on DNS tunnel servers.

=item enable-dns = yes|true|on | no|false|off

Enable the DNS tunneling protocol on this node, either as server or as
client (only available when gvpe was compiled with C<--enable-dns>).

B<WARNING:> Parsing and generating DNS packets is rather tricky. The code
almost certainly contains buffer overflows and other, likely exploitable,
bugs. You have been warned.

This is the worst choice of transport protocol with respect to overhead
(overhead can be 2-3 times higher than the transferred data), and probably
the best choice when tunneling through firewalls.

=item enable-rawip = yes|true|on | no|false|off

Enable the RAW IPv4 transport using the C<ip-proto> protocol
(default: C<no>). This is the best choice, since the minimum overhead per
packet is only 38 bytes, as opposed to UDP's 58 (or TCP's 60+).

=item enable-tcp = yes|true|on | no|false|off

Enable the TCPv4 transport using the C<tcp-port> port
(default: C<no>). Support for this horribly unsuitable protocol is only
available when gvpe was compiled using the C<--enable-tcp> option. Never
use this transport unless you really must, it is very inefficient and
resource-intensive compared to the other transports (except for DNS, which
is worse).

=item enable-udp = yes|true|on | no|false|off

Enable the UDPv4 transport using the C<udp-port> port (default: C<no>,
unless no other protocol is enabled for a node, in which case this
protocol is enabled automatically). This is a good general choice since
UDP tunnels well through many firewalls.

NOTE: Please specify C<enable-udp = yes> if you want t use it even though
it might get switched on automatically, as some future version might
default to another default protocol.

=item inherit-tos = yes|true|on | no|false|off

Wether to inherit the TOS settings of packets sent to the tunnel when
sending packets to this node (default: C<yes>). If set to C<yes> then
outgoing tunnel packets will have the same TOS setting as the packets sent
to the tunnel device, which is usually what you want.

=item max-retry = positive-number

The maximum interval in seconds (default: C<3600>, one hour) between
retries to establish a connection to this node. When a connection cannot
be established, gvpe uses exponential backoff capped at this value. It's
sometimes useful to set this to a much lower value (e.g. C<120>) on
connections to routers that usually are stable but sometimes are down, to
assure quick reconnections even after longer downtimes.

=item router-priority = 0 | 1 | positive-number>=2

Sets the router priority of the given host (default: C<0>, disabled). If
some host tries to connect to another host without a hostname, it asks
the router host for it's IP address. The router host is the one with the
highest priority larger than C<1> that is currently reachable.

Make sure all hosts always connect (C<connect = always>) to the router
hosts, otherwise connecting to them might be impossible.

The special value C<1> allows other hosts to route through the router
host, but they will never route through it by default. The value C<0>
disables routing. The idea behind this is that some hosts can, if
required, bump the C<router-priority> setting to higher than C<1> in their
local config to route through specific hosts. If C<router-priority> is
C<0>, then routing will be refused, so C<1> serves as a "enable, but do
not use by default" switch.

=item tcp-port = port-number

Similar to C<udp-port> (default: C<655>), but sets the TCP port number.

=item udp-port = port-number

Sets the port number used by the UDP protocol (default: C<655>, not
officially assigned by IANA!).

=back

=head1 CONFIG DIRECTORY LAYOUT

The default (or recommended) directory layout for the config directory is:

=over 4

=item X<gvpe.conf>

The config file.

=item X<if-up>

The if-up script

=item X<node-up>, X<node-down>

If used the node up or node-down scripts.

=item X<hostkey>

The private key (taken from C<hostkeys/nodename>) of the current host.

=item X<pubkey/nodename>

The public keys of the other nodes, one file per node.

=back

=head1 SEE ALSO

gvpe(5), gvpe(8), gvpectrl(8).

=head1 AUTHOR

Marc Lehmann <gvpe@plan9.de>

Revision:	1.9
Committed:	Mon Mar 14 17:40:01 2005 UTC (19 years, 2 months ago) by pcg
Branch:	MAIN
Changes since 1.8:	+5 -1 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	pcg	1.1	=head1 NAME
2
3			gvpe.conf - configuration file for the GNU VPE daemon
4
5			=head1 SYNOPSIS
6
7			udp-port = 407
8			mtu = 1492
9			ifname = vpn0
10
11			node = branch1
12			hostname = 1.2.3.4
13
14			node = branch2
15			hostname = www.example.net
16			udp-port = 500 # this host uses a different udp-port
17
18			node = branch3
19			connect = ondemand
20
21			=head1 DESCRIPTION
22
23			The gvpe config file consists of a series of lines that contain C<variable
24			= value> pairs. Empty lines are ignored. Comments start with a C<#> and
25			extend to the end of the line. They can be used on their own lines, or
26			after any directives. Spaces are allowed before or after the C<=> sign or
27			after values, but not within the variable names or values themselves.
28
29			The only exception to the above is the "on" directive that can prefix any
30			C<name = value> setting and will only "execute" it on the named node, or
31			(if the nodename starts with "!") on all nodes except the named one.
32
33			name = value
34			on branch1 loglevel = noise
35			on !branch2 connect = ondemand
36
37			All settings are executed "in order", that is, later settings of the same
38			variable overwrite earlier ones.
39
40			=head1 ANATOMY OF A CONFIG FILE
41
42			Usually, a config file starts with global settings (like the udp port to
43			listen on), followed by node-specific sections that begin with a C<node =
44			nickname> line.
45
46			Every node that is part of the network must have a section that starts
47			with C<node = nickname>. The number and order of the nodes is important
48			and must be the same on all hosts. It is not uncommon for node sections to
49			be completely empty - if the default values are right.
50
51			Node-specific settings can be used at any time. If used before the first
52			node section they will set the default values for all following nodes.
53
54			=head1 CONFIG VARIABLES
55
56			=head2 GLOBAL SETTINGS
57
58			Global settings will affect the behaviour of the running gvpe daemon, that
59			is, they are in some sense node-specific (config files can set different
60			values on different nodes using C<on>), but will affect the behaviour of
61			the gvpe daemon and all connections it creates.
62
63			=over 4
64
65	pcg	1.6	=item dns-forw-host = hostname/ip
66	pcg	1.1
67	pcg	1.6	The dns server to forward dns requests to for the DNS tunnel protocol
68			(default: C<127.0.0.1>, changing it is highly recommended).
69	pcg	1.1
70	pcg	1.6	=item dns-forw-port = port-number
71	pcg	1.1
72	pcg	1.6	The port where the C<dns-forw-host> is to be contacted (default: C<53>,
73			which is fine in most cases).
74	pcg	1.1
75			=item if-up = relative-or-absolute-path
76
77			Sets the path of a script that should be called immediately after the
78			network interface is initialized (but not neccessarily up). The following
79			environment variables are passed to it (the values are just examples):
80
81			=over 4
82
83			=item CONFBASE=/etc/gvpe
84
85			The configuration base directory.
86
87			=item IFNAME=vpn0
88
89			The interface to initialize.
90
91			=item MTU=1436
92
93			The MTU to set the interface to. You can use lower values (if done
94			consistently on all hosts), but this is usually ineffective.
95
96			=item MAC=fe:fd:80:00:00:01
97
98			The MAC address to set the interface to. The script must set the
99			interface MAC to this value. You will most likely use one of these:
100
101			ip link set $IFNAME address $MAC mtu $MTU up # GNU/Linux
102			ifconfig $IFNAME ether $MAC mtu $MTU up # FreeBSD
103
104			Please see the C<gvpe.osdep(5)> manpage for platform-specific information.
105
106			=item IFTYPE=native # or tincd
107
108			=item IFSUBTYPE=linux # or freebsd, darwin etc..
109
110			The interface type (C<native> or C<tincd>) and the subtype (usually the os
111			name in lowercase) that this gvpe was configured for. Can be used to select
112			the correct syntax to use for network-related commands.
113
114			=item NODENAME=branch1
115
116			The nickname of the current node, as passed to the gvpe daemon.
117
118			=item NODEID=1
119
120			The numerical node id of the current node. The first node mentioned in the
121			config file gets ID 1, the second ID 2 and so on.
122
123			=back
124
125			Here is a simple if-up script:
126
127			#!/bin/sh
128			ip link set $IFNAME address $MAC mtu $MTU up
129			[ $NODENAME = branch1 ] && ip addr add 10.0.0.1 dev $IFNAME
130			[ $NODENAME = branch2 ] && ip addr add 10.1.0.1 dev $IFNAME
131			ip route add 10.0.0.0/8 dev $IFNAME
132
133			More complicated examples (using routing to reduce arp traffic) can be
134			found in the etc/ subdirectory of the distribution.
135
136	pcg	1.6	=item ifname = devname
137
138			Sets the tun interface name to the given name. The default is OS-specific
139			and most probably something like C<tun0>.
140
141			=item ifpersist = yes\|true\|on \| no\|false\|off
142
143			Should the tun/tap device be made persistent, that is, should the device
144			stay up even when gvpe exits? Some versions of the tunnel device have
145			problems sending packets when gvpe is restarted in persistent mode, so
146			if the connections can be established but you cannot send packets from
147			the local node, try to set this to C<off> and do an ifconfig down on the
148			device.
149
150			=item ip-proto = numerical-ip-protocol
151
152			Sets the protocol number to be used for the rawip protocol. This is a
153			global option because all hosts must use the same protocol, and since
154			there are no port numbers, you cannot easily run more than one gvpe
155			instance using the same protocol, nor can you share the protocol with
156			other programs.
157
158			The default is 47 (GRE), which has a good chance of tunneling through
159			firewalls (but note that the rawip protocol is not GRE compatible). Other
160			common choices are 50 (IPSEC, ESP), 51 (IPSEC, AH), 4 (IPIP tunnels) or 98
161			(ENCAP, rfc1241)
162
163			=item http-proxy-host = hostname/ip
164
165			The C<http-proxy-*> family of options are only available if gvpe was
166			compiled with the C<--enable-http-proxy> option and enable tunneling of
167			tcp connections through a http proxy server.
168
169			C<http-proxy-host> and C<http-proxy-port> should specify the hostname and
170			port number of the proxy server. See C<http-proxy-loginpw> if your proxy
171			requires authentication.
172
173			Please note that gvpe will still try to resolve all hostnames in the
174			configuration file, so if you are behind a proxy without access to a dns
175			server better use numerical IP addresses.
176
177			To make best use of this option disable all protocols except tcp in your
178			config file and make sure your routers (or all other hosts) are listening
179			on a port that the proxy allows (443, https, is a common choice).
180
181			If you have a router, connecting to it will suffice. Otherwise tcp must be
182			enabled on all hosts.
183
184			Example:
185
186			http-proxy-host = proxy.example.com
187			http-proxy-port = 3128 # 8080 is another common choice
188			http-proxy-auth = schmorp:grumbeere
189
190			=item http-proxy-port = proxy-tcp-port
191
192			The port where your proxy server listens.
193
194			=item http-proxy-auth = login:password
195
196			The optional login and password used to authenticate to the proxy server,
197			seperated by a literal colon (C<:>). Only basic authentication is
198			currently supported.
199
200			=item keepalive = seconds
201
202			Sets the keepalive probe interval in seconds (default: C<60>). After this
203			many seconds of inactivity the daemon will start to send keepalive probe
204			every 5 seconds until it receives a reply from the other end. If no reply
205			is received within 30 seconds, the peer is considered unreachable and the
206			connection is closed.
207
208			=item loglevel = noise\|trace\|debug\|info\|notice\|warn\|error\|critical
209
210			Set the logging level. Connection established messages are logged at level
211			C<info>, notable errors are logged with C<error>. Default is C<info>.
212
213			=item mtu = bytes
214
215			Sets the maximum MTU that should be used on outgoing packets (basically
216			the MTU of the outgoing interface) The daemon will automatically calculate
217			maximum overhead (e.g. udp header size, encryption blocksize...) and pass
218			this information to the C<if-up> script.
219
220			Recommended values are 1500 (ethernet), 1492 (pppoe), 1472 (pptp).
221
222			This value must be the minimum of the mtu values of all hosts.
223
224			=item node = nickname
225
226			Not really a config setting but introduces a node section. The nickname is
227			used to select the right configuration section and must be passed as an
228			argument to the gvpe daemon.
229
230	pcg	1.1	=item node-up = relative-or-absolute-path
231
232			Sets a command (default: no script) that should be called whenever a
233			connection is established (even on rekeying operations). In addition
234			to the variables passed to C<if-up> scripts, the following environment
235			variables will be set:
236
237			=over 4
238
239			=item DESTNODE=branch2
240
241			The name of the remote node.
242
243			=item DESTID=2
244
245			The node id of the remote node.
246
247			=item DESTIP=188.13.66.8
248
249			The numerical IP address of the remote host (gvpe accepts connections from
250			everywhere, as long as the other host can authenticate itself).
251
252			=item DESTPORT=655 # deprecated
253
254			The UDP port used by the other side.
255
256			=item STATE=UP
257
258			Node-up scripts get called with STATE=UP, node-down scripts get called
259			with STATE=DOWN.
260
261			=back
262
263			Here is a nontrivial example that uses nsupdate to update the name => ip
264			mapping in some dns zone:
265
266			#!/bin/sh
267			{
268			echo update delete $DESTNODE.lowttl.example.net. a
269			echo update add $DESTNODE.lowttl.example.net. 1 in a $DESTIP
270			echo
271			} \| nsupdate -d -k $CONFBASE:key.example.net.
272
273			=item node-down = relative-or-absolute-path
274
275			Same as C<node-up>, but gets called whenever a connection is lost.
276
277	pcg	1.6	=item pid-file = path
278
279			The path to the pid file to check and create
280			(default: C<LOCALSTATEDIR/run/gvpe.pid>).
281
282			=item private-key = relative-path-to-key
283
284			Sets the path (relative to the config directory) to the private key
285			(default: C<hostkey>). This is a printf format string so every C<%> must
286			be doubled. A single C<%s> is replaced by the hostname, so you could
287			use paths like C<hostkeys/%s> to fetch the files at the location where
288			C<gvpectrl> puts them.
289	pcg	1.1
290	pcg	1.6	Since only the private key file of the current node is used and the
291			private key file should be kept secret per-host to avoid spoofings, it is
292			not recommended to use this feature.
293	pcg	1.1
294	pcg	1.6	=item rekey = seconds
295	pcg	1.1
296	pcg	1.6	Sets the rekeying interval in seconds (default: C<3600>). Connections are
297			reestablished every C<rekey> seconds.
298	pcg	1.1
299	pcg	1.6	=back
300	pcg	1.1
301	pcg	1.6	=head2 NODE SPECIFIC SETTINGS
302	pcg	1.1
303	pcg	1.6	The following settings are node-specific, that is, every node can have
304			different settings, even within the same gvpe instance. Settings that are
305			executed before the first node section set the defaults, settings that are
306			executed within a node section only apply to the given node.
307	pcg	1.1
308	pcg	1.6	=over 4
309	pcg	1.1
310	pcg	1.6	=item compress = yes\|true\|on \| no\|false\|off
311	pcg	1.1
312	pcg	1.6	Wether to compress data packets sent to this host (default: C<yes>).
313			Compression is really cheap even on slow computers and has no size
314			overhead at all, so enabling this is a good idea.
315	pcg	1.1
316	pcg	1.6	=item connect = ondemand \| never \| always \| disabled
317	pcg	1.1
318	pcg	1.6	Sets the connect mode (default: C<always>). It can be C<always> (always
319			try to establish and keep a connection to the given host), C<never>
320			(never initiate a connection to the given host, but accept connections),
321			C<ondemand> (try to establish a connection on the first packet sent, and
322			take it down after the keepalive interval) or C<disabled> (node is bad,
323			don't talk to it).
324	pcg	1.1
325	pcg	1.6	=item dns-domain = domain-suffix
326	pcg	1.1
327	pcg	1.7	The DNS domain suffix that points to the DNS tunnel server for this node.
328	pcg	1.1
329	pcg	1.6	The domain must point to a NS record that points to the I<dns-hostname>,
330			i.e.
331	pcg	1.1
332	pcg	1.6	dns-domainname = tunnel.example.net
333			dns-hostname = tunnel-server.example.net
334	pcg	1.1
335	pcg	1.6	Corresponds to the following DNS entries in the C<example.net> domain:
336	pcg	1.1
337	pcg	1.6	tunnel.example.net. NS tunnel-server.example.net.
338			tunnel-server.example.net. A 13.13.13.13
339	pcg	1.1
340	pcg	1.6	=item dns-hostname = hostname/ip
341	pcg	1.1
342	pcg	1.6	The address to bind the DNS tunnel socket to, similar to the C<hostname>,
343			but for the DNS tunnel protocol only. Default: C<0.0.0.0>, but that might
344			change.
345	pcg	1.1
346	pcg	1.6	=item dns-port = port-number
347	pcg	1.1
348	pcg	1.8	The port to bind the DNS tunnel socket to. Must be C<53> on DNS tunnel servers.
349	pcg	1.1
350	pcg	1.7	=item enable-dns = yes\|true\|on \| no\|false\|off
351
352	pcg	1.8	Enable the DNS tunneling protocol on this node, either as server or as
353			client (only available when gvpe was compiled with C<--enable-dns>).
354
355	pcg	1.9	B<WARNING:> Parsing and generating DNS packets is rather tricky. The code
356			almost certainly contains buffer overflows and other, likely exploitable,
357			bugs. You have been warned.
358
359	pcg	1.8	This is the worst choice of transport protocol with respect to overhead
360	pcg	1.9	(overhead can be 2-3 times higher than the transferred data), and probably
361	pcg	1.8	the best choice when tunneling through firewalls.
362	pcg	1.7
363	pcg	1.1	=item enable-rawip = yes\|true\|on \| no\|false\|off
364
365			Enable the RAW IPv4 transport using the C<ip-proto> protocol
366	pcg	1.8	(default: C<no>). This is the best choice, since the minimum overhead per
367			packet is only 38 bytes, as opposed to UDP's 58 (or TCP's 60+).
368	pcg	1.1
369	pcg	1.6	=item enable-tcp = yes\|true\|on \| no\|false\|off
370
371			Enable the TCPv4 transport using the C<tcp-port> port
372			(default: C<no>). Support for this horribly unsuitable protocol is only
373			available when gvpe was compiled using the C<--enable-tcp> option. Never
374	pcg	1.8	use this transport unless you really must, it is very inefficient and
375			resource-intensive compared to the other transports (except for DNS, which
376			is worse).
377	pcg	1.6
378	pcg	1.1	=item enable-udp = yes\|true\|on \| no\|false\|off
379
380	pcg	1.5	Enable the UDPv4 transport using the C<udp-port> port (default: C<no>,
381			unless no other protocol is enabled for a node, in which case this
382			protocol is enabled automatically). This is a good general choice since
383			UDP tunnels well through many firewalls.
384
385			NOTE: Please specify C<enable-udp = yes> if you want t use it even though
386			it might get switched on automatically, as some future version might
387			default to another default protocol.
388	pcg	1.1
389	pcg	1.6	=item inherit-tos = yes\|true\|on \| no\|false\|off
390
391			Wether to inherit the TOS settings of packets sent to the tunnel when
392			sending packets to this node (default: C<yes>). If set to C<yes> then
393			outgoing tunnel packets will have the same TOS setting as the packets sent
394			to the tunnel device, which is usually what you want.
395
396			=item max-retry = positive-number
397	pcg	1.1
398	pcg	1.8	The maximum interval in seconds (default: C<3600>, one hour) between
399	pcg	1.6	retries to establish a connection to this node. When a connection cannot
400			be established, gvpe uses exponential backoff capped at this value. It's
401			sometimes useful to set this to a much lower value (e.g. C<120>) on
402			connections to routers that usually are stable but sometimes are down, to
403	pcg	1.8	assure quick reconnections even after longer downtimes.
404	pcg	1.1
405	pcg	1.8	=item router-priority = 0 \| 1 \| positive-number>=2
406	pcg	1.1
407			Sets the router priority of the given host (default: C<0>, disabled). If
408			some host tries to connect to another host without a hostname, it asks
409			the router host for it's IP address. The router host is the one with the
410	pcg	1.2	highest priority larger than C<1> that is currently reachable.
411	pcg	1.1
412	pcg	1.2	Make sure all hosts always connect (C<connect = always>) to the router
413			hosts, otherwise connecting to them might be impossible.
414
415			The special value C<1> allows other hosts to route through the router
416			host, but they will never route through it by default. The value C<0>
417			disables routing. The idea behind this is that some hosts can, if
418			required, bump the C<router-priority> setting to higher than C<1> in their
419			local config to route through specific hosts. If C<router-priority> is
420			C<0>, then routing will be refused, so C<1> serves as a "enable, but do
421			not use by default" switch.
422
423	pcg	1.6	=item tcp-port = port-number
424	pcg	1.1
425	pcg	1.6	Similar to C<udp-port> (default: C<655>), but sets the TCP port number.
426	pcg	1.1
427	pcg	1.6	=item udp-port = port-number
428	pcg	1.1
429	pcg	1.6	Sets the port number used by the UDP protocol (default: C<655>, not
430			officially assigned by IANA!).
431	pcg	1.1
432			=back
433
434			=head1 CONFIG DIRECTORY LAYOUT
435
436			The default (or recommended) directory layout for the config directory is:
437
438			=over 4
439
440	pcg	1.4	=item X<gvpe.conf>
441	pcg	1.1
442			The config file.
443
444	pcg	1.4	=item X<if-up>
445	pcg	1.1
446			The if-up script
447
448	pcg	1.4	=item X<node-up>, X<node-down>
449	pcg	1.1
450			If used the node up or node-down scripts.
451
452	pcg	1.4	=item X<hostkey>
453	pcg	1.1
454			The private key (taken from C<hostkeys/nodename>) of the current host.
455
456	pcg	1.4	=item X<pubkey/nodename>
457	pcg	1.1
458			The public keys of the other nodes, one file per node.
459
460			=back
461
462			=head1 SEE ALSO
463
464			gvpe(5), gvpe(8), gvpectrl(8).
465
466			=head1 AUTHOR
467
468			Marc Lehmann <gvpe@plan9.de>
469