[ViewVC] Diff of: cvs/gvpe/doc/gvpe.conf.5.pod

Comparing gvpe/doc/gvpe.conf.5.pod (file contents):
Revision 1.14 by pcg, Tue Jun 21 08:46:53 2005 UTC vs.
Revision 1.22 by pcg, Mon Sep 1 06:06:11 2008 UTC

 gvpe.conf - configuration file for the GNU VPE daemon
 =head1 SYNOPSIS
+   # global options for all nodes
    udp-port = 407
    mtu = 1492
    ifname = vpn0
+   # first node is named branch1 and is at 1.2.3.4
    node = branch1
    hostname = 1.2.3.4
+   # second node uses dns to resolve the address
    node = branch2
    hostname = www.example.net
    udp-port = 500	# this host uses a different udp-port
+   # third node has no fixed ip address
    node = branch3
    connect = ondemand
 =head1 DESCRIPTION
 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
+For example, set the MTU to C<1450> everywhere, loglevel to C<noise> on
+branch1, and connect to C<ondemand> everywhere but on branch2:
+   mtu = 1450
    on branch1 loglevel = noise
    on !branch2 connect = ondemand
-All settings are executed "in order", that is, later settings of the same
+All settings are applied "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
+Usually, a config file starts with a few global settings (like the UDP
-listen on), followed by node-specific sections that begin with a C<node =
+port to listen on), followed by node-specific sections that begin with a
-nickname> line.
+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
+and must be the same on all nodes. 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.
 =over 4
 =item dns-forw-host = hostname/ip
-The dns server to forward dns requests to for the DNS tunnel protocol
+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>,
 (default: C<100>). GVPE will never issue more requests then the given
 limit without receiving replies. In heavily overloaded situations it might
 help to set this to a low number (e.g. C<3> or even C<1>) to limit the
 number of parallel requests.
-The default should be working ok for most links.
+The default should be working OK for most links.
 =item dns-overlap-factor = float
 The DNS transport uses the minimum request latency (B<min_latency>) seen
 during a connection as it's timing base. This factor (default: C<0.5>,
 request might be generated every B<min_latency> seconds, which means on
 average there should only ever be one outstanding request.  A factor of
 C<0.5> means that GVPE will send requests twice as often as the minimum
 latency measured.
-For congested or picky dns forwarders you could use a value nearer to or
+For congested or picky DNS forwarders you could use a value nearer to or
 exceeding C<1>.
-The default should be working ok for most links.
+The default should be working OK for most links.
 =item dns-send-interval = send-interval-in-seconds
 The minimum send interval (= maximum rate) that the DNS transport will
 use to send new DNS requests. GVPE will not exceed this rate even when
 not send more than 100 DNS requests per connection per second. For
 high-bandwidth links you could go lower, e.g. to C<0.001> or so. For
 congested or rate-limited links, you might want to go higher, say C<0.1>,
 C<0.2> or even higher.
-The default should be working ok for most links.
+The default should be working OK for most links.
 =item dns-timeout-factor = float
 Factor to multiply the C<min_latency> (see C<dns-overlap-factor>) by to
 get request timeouts. The default of C<8> means that the DNS transport
 will resend the request when no reply has been received for longer than
 eight times the minimum (= expected) latency, assuming the request or
 reply has been lost.
-For congested links a higher value might be necessary (e.g. C<30>). If the
+For congested links a higher value might be necessary (e.g. C<30>). If
-link is very stable lower values (e.g. C<2>) might work nicely. Values
+the link is very stable lower values (e.g. C<2>) might work
-near or below C<1> makes no sense whatsoever.
+nicely. Values near or below C<1> makes no sense whatsoever.
-The default should be working ok for most links.
+The default should be working OK for most links but will result in low
+throughput if packet loss is high.
 =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
+network interface is initialized (but not necessarily up). The following
 environment variables are passed to it (the values are just examples).
 Variables that have the same value on all nodes:
 =over 4
 select the correct syntax to use for network-related commands.
 =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.
+consistently on all nodes), but this is usually either inefficient or
+simply ineffective.
 =item NODES=5
 The number of nodes in this GVPE network.
 =item MAC=fe:fd:80:00:00:01
 The MAC address the network interface has to use.
 Might be used to initialize interfaces on platforms where GVPE does not
-do this automatically.  Please see the C<gvpe.osdep(5)> manpage for
+do this automatically.  Please see the C<gvpe.osdep(5)> man page for
 platform-specific information.
 =item NODENAME=branch1
 The nickname of the node.
    ip link set $IFNAME 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
+More complicated examples (using routing to reduce ARP traffic) can be
-found in the etc/ subdirectory of the distribution.
+found in the F<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>.
 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
+global option because all nodes 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
+The default is 47 (GRE), which has a good chance of tunneling
-firewalls (but note that the rawip protocol is not GRE compatible). Other
+through firewalls (but note that gvpe's rawip protocol is not GRE
-common choices are 50 (IPSEC, ESP), 51 (IPSEC, AH), 4 (IPIP tunnels) or 98
+compatible). Other common choices are 50 (IPSEC, ESP), 51 (IPSEC, AH), 4
-(ENCAP, rfc1241)
+(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
 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
+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
+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
+config file and make sure your routers (or all other nodes) 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
+If you have a router, connecting to it will suffice. Otherwise TCP must be
-enabled on all hosts.
+enabled on all nodes.
 Example:
    http-proxy-host = proxy.example.com
    http-proxy-port = 3128	# 8080 is another common choice
 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
+separated 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
+every 3 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
+is received within 15 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
 =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
+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.
+This value must be the minimum of the MTU values of all nodes.
 =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
+Sets a command (default: none) that should be called whenever a connection
-connection is established (even on rekeying operations). In addition to
+is established (even on rekeying operations). Note that node-up/down
+scripts will be run asynchronously, but execution is serialised, so there
+will only ever be one such script running.
-all the variables passed to C<if-up> scripts, the following environment
+In addition to all the variables passed to C<if-up> scripts, the following
-variables will be set:
+environment variables will be set:
 =over 4
 =item DESTNODE=branch2
 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
+The numerical IP address of the remote node (gvpe accepts connections from
-everywhere, as long as the other host can authenticate itself).
+everywhere, as long as the other node can authenticate itself).
 =item DESTPORT=655 # deprecated
 The UDP port used by the other side.
 with STATE=DOWN.
 =back
 Here is a nontrivial example that uses nsupdate to update the name => ip
-mapping in some dns zone:
+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
 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
+private key file should be kept secret per-node to avoid spoofing, 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.
+reestablished every C<rekey> seconds, making them use a new encryption
+key.
 =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
+set before the first node section set the defaults, settings that are
-executed within a node section only apply to the given node.
+set within a node section only apply to the given node.
 =over 4
+=item allow-direct = nodename
+Allow direct connections to this node. See C<deny-direct> for more info.
 =item compress = yes|true|on | no|false|off
-Wether to compress data packets sent to this host (default: C<yes>).
+Wether to compress data packets sent to this node (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.
+overhead at all, so enabling this is often 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>
+try to establish and keep a connection to the given node), 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
+C<ondemand> (try to establish a connection when there are outstanding
-take it down after the keepalive interval) or C<disabled> (node is bad,
+packets in the queue and take it down after the keepalive interval) or
-don't talk to it).
+C<disabled> (node is bad, don't talk to it).
+Routers will automatically be forced to C<always> unless they are
+C<disabled>, to ensure all nodes can talk to each other.
+=item deny-direct = nodename | *
+Deny direct connections to the specified node (or all nodes when C<*>
+is given). Only one node can be specified, but you can use multiple
+C<allow-direct> and C<deny-direct> statements. This only makes sense in
+networks with routers, as routers are required for indirect connections.
+Sometimes, a node cannot reach some other nodes for reasons of network
+connectivity. For example, a node behind a firewall that only allows
+connections to/from a single other node in the network. In this case one
+should specify C<deny-direct = *> and C<allow-direct = othernodename> (the other
+node I<must> be a router for this to work).
+The algorithm to check whether a connection may be direct is as follows:
+1. Other node mentioned in an C<allow-direct>? If yes, allow the connection.
+2. Other node mentioned in a C<deny-direct>? If yes, deny direct connections.
+3. Allow the connection.
+That is, C<allow-direct> takes precedence over C<deny-direct>.
+The check is done in both directions, i.e. both nodes must allow a direct
+connection before one is attempted, so you only need to specify connect
+limitations on one node.
 =item dns-domain = domain-suffix
 The DNS domain suffix that points to the DNS tunnel server for this node.
 =item enable-icmp = yes|true|on | no|false|off
 See gvpe.protocol(7) for a description of the ICMP transport protocol.
-Enable the ICMP transport using icmp packets of type C<icmp-type> on this
+Enable the ICMP transport using ICMP packets of type C<icmp-type> on this
 node.
 =item enable-rawip = yes|true|on | no|false|off
 See gvpe.protocol(7) for a description of the RAW IP transport protocol.
 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).
-NOTE: Please specify C<enable-udp = yes> if you want t use it even though
+NOTE: Please specify C<enable-udp = yes> if you want to use it even though
 it might get switched on automatically, as some future version might
 default to another default protocol.
+=item hostname = hostname | ip    [can not be defaulted]
+Forces the address of this node to be set to the given DNS hostname or IP
+address. It will be resolved before each connect request, so dyndns should
+work fine. If this setting is not specified and a router is available,
+then the router will be queried for the address of this node. Otherwise,
+the connection attempt will fail.
+Note that DNS resolving is done synchronously, pausing the daemon. If that
+is an issue you need to specify IP addresses.
 =item icmp-type = integer
 Sets the type value to be used for outgoing (and incoming) packets sent
 via the ICMP transport.
 The default is C<0> (which is C<echo-reply>, also known as
-"ping-replies"). Other useful values include C<8> (C<echo-request>, a.k.a.
+"ping-reply"). Other useful values include C<8> (C<echo-request>, a.k.a.
 "ping") and C<11> (C<time-exceeded>), but any 8-bit value can be used.
 =item if-up-data = value
 The value specified using this directive will be passed to the C<if-up>
 =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
+be established, gvpe uses exponential back-off 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 max-ttl = seconds
+Expire packets that couldn't be sent after this many seconds
+(default: C<60>). Gvpe will normally queue packets for a node without an
+active connection, in the hope of establishing a connection soon. This
+value specifies the maximum lifetime a packet will stay in the queue, if a
+packet gets older, it will be thrown away.
+=item max-queue = positive-number>=1
+The maximum number of packets that will be queued (default: C<512>)
+for this node. If more packets are sent then earlier packets will be
+expired. See C<max-ttl>, above.
 =item router-priority = 0 | 1 | positive-number>=2
-Sets the router priority of the given host (default: C<0>, disabled). If
+Sets the router priority of the given node (default: C<0>, disabled).
-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
+If some node tries to connect to another node but it doesn't have a
-hosts, otherwise connecting to them might be impossible.
+hostname, it asks a router node for it's IP address. The router node
+chosen is the one with the highest priority larger than C<1> that is
+currently reachable. This is called a I<mediated> connection, as the
+connection itself will still be direct, but it uses another node to
+mediate between the two nodes.
+The value C<0> disables routing, that means if the node receives a packet
+not for itself it will not forward it but instead drop it.
 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>
+host, but they will never route through it by default (i.e. the config
-disables routing. The idea behind this is that some hosts can, if
+file of another node needs to specify a router priority higher than one
+to choose such a node for routing).
+The idea behind this is that some hosts can, if required, bump the
-required, bump the C<router-priority> setting to higher than C<1> in their
+C<router-priority> setting to higher than C<1> in their local config to
-local config to route through specific hosts. If C<router-priority> is
+route through specific hosts. If C<router-priority> is C<0>, then routing
-C<0>, then routing will be refused, so C<1> serves as a "enable, but do
+will be refused, so C<1> serves as a "enable, but do not use by default"
-not use by default" switch.
+switch.
+Nodes with C<router-priority> set to C<2> or higher will always be forced
+to C<connect> = C<always> (unless they are C<disabled>).
 =item tcp-port = port-number
 Similar to C<udp-port> (default: C<655>), but sets the TCP port number.
 The default (or recommended) directory layout for the config directory is:
 =over 4
-=item X<gvpe.conf>
+=item gvpe.conf
 The config file.
-=item X<if-up>
+=item if-up
 The if-up script
-=item X<node-up>, X<node-down>
+=item node-up, node-down
 If used the node up or node-down scripts.
-=item X<hostkey>
+=item hostkey
 The private key (taken from C<hostkeys/nodename>) of the current host.
-=item X<pubkey/nodename>
+=item pubkey/nodename
 The public keys of the other nodes, one file per node.
 =back

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Comparing gvpe/doc/gvpe.conf.5.pod (file contents): Revision 1.14 by pcg, Tue Jun 21 08:46:53 2005 UTC vs. Revision 1.22 by pcg, Mon Sep 1 06:06:11 2008 UTC

Diff Legend

Comparing gvpe/doc/gvpe.conf.5.pod (file contents):
Revision 1.14 by pcg, Tue Jun 21 08:46:53 2005 UTC vs.
Revision 1.22 by pcg, Mon Sep 1 06:06:11 2008 UTC