--- gvpe/doc/gvpe.conf.5.pod 2005/03/06 18:34:46 1.6 +++ gvpe/doc/gvpe.conf.5.pod 2008/08/10 22:18:58 1.20 @@ -23,8 +23,8 @@ The gvpe config file consists of a series of lines that contain C 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. +after any directives. Whitespace is allowed around 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 setting and will only "execute" it on the named node, or @@ -45,7 +45,7 @@ Every node that is part of the network must have a section that starts with C. 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 @@ -72,11 +72,66 @@ The port where the C is to be contacted (default: C<53>, which is fine in most cases). +=item dns-max-outstanding = integer-number-of-requests + +The maximum number of outstanding DNS transport requests +(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. + +=item dns-overlap-factor = float + +The DNS transport uses the minimum request latency (B) seen +during a connection as it's timing base. This factor (default: C<0.5>, +must be > 0) is multiplied by B to get the maximum sending +rate (= minimum send interval), i.e. a factor of C<1> means that a new +request might be generated every B 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 +exceeding C<1>. + +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 +the latency is very low. The default is C<0.01>, which means GVPE will +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. + +=item dns-timeout-factor = float + +Factor to multiply the C (see C) 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 link is very stable lower values (e.g. C<2>) might work +nicely. Values near or below C<1> makes no sense whatsoever. + +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 -environment variables are passed to it (the values are just examples): +environment variables are passed to it (the values are just examples). + +Variables that have the same value on all nodes: =over 4 @@ -86,46 +141,65 @@ =item IFNAME=vpn0 -The interface to initialize. +The network interface to initialize. + +=item IFTYPE=native # or tincd + +=item IFSUBTYPE=linux # or freebsd, darwin etc.. + +The interface type (C or C) 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 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 MAC=fe:fd:80:00:00:01 +=item NODES=5 -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: +The number of nodes in this GVPE network. - ip link set $IFNAME address $MAC mtu $MTU up # GNU/Linux - ifconfig $IFNAME ether $MAC mtu $MTU up # FreeBSD +=back -Please see the C manpage for platform-specific information. +Variables that are node-specific and with values pertaining to the node +running this GVPE: -=item IFTYPE=native # or tincd +=over 4 -=item IFSUBTYPE=linux # or freebsd, darwin etc.. +=item IFUPDATA=string -The interface type (C or C) 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. +The value of the configuration directive C. + +=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 manpage for +platform-specific information. =item NODENAME=branch1 -The nickname of the current node, as passed to the gvpe daemon. +The nickname of the node. =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. +The numerical node ID of the node running this instance of GVPE. The first +node mentioned in the config file gets ID 1, the second ID 2 and so on. =back +In addition, all node-specific variables (except C) will be +available with a postfix of C<_nodeid>, which contains the value for that +node, e.g. the C variable contains the MAC address of node #1, while +the C variable contains the name of node #22. + Here is a simple if-up script: #!/bin/sh - ip link set $IFNAME address $MAC mtu $MTU up + 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 @@ -150,7 +224,7 @@ =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. @@ -175,11 +249,11 @@ 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 +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 -enabled on all hosts. +enabled on all nodes. Example: @@ -219,7 +293,7 @@ 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 @@ -229,10 +303,13 @@ =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 scripts, the following environment -variables will be set: +Sets a command (default: none) that should be called whenever a connection +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. + +In addition to all the variables passed to C scripts, the following +environment variables will be set: =over 4 @@ -246,8 +323,8 @@ =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). +The numerical IP address of the remote node (gvpe accepts connections from +everywhere, as long as the other node can authenticate itself). =item DESTPORT=655 # deprecated @@ -288,7 +365,7 @@ C 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 spoofings, it is not recommended to use this feature. =item rekey = seconds @@ -302,30 +379,63 @@ 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. +set before the first node section set the defaults, settings that are +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 for more info. + =item compress = yes|true|on | no|false|off -Wether to compress data packets sent to this host (default: C). +Wether to compress data packets sent to this node (default: C). 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). It can be C (always -try to establish and keep a connection to the given host), C +try to establish and keep a connection to the given node), C (never initiate a connection to the given host, but accept connections), -C (try to establish a connection on the first packet sent, and -take it down after the keepalive interval) or C (node is bad, -don't talk to it). +C (try to establish a connection when there are outstanding +packets in the queue and take it down after the keepalive interval) or +C (node is bad, don't talk to it). + +Routers will automatically be forced to C unless they are +C, 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 and C 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 +conenctions to/from a single other node in the network. In this case one +should specify C and C (the other +node I be a router for this to work). + +The algorithm to check wether a connection may be direct is as follows: + +1. Other node mentioned in a C? If yes, allow the connection. + +2. Other node mentioned in a C? If yes, deny direct connections. + +3. Allow the connection. + +That is, C takes precedence over C. + +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. Needs to be -set on both client and server. +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, i.e. @@ -346,34 +456,73 @@ =item dns-port = port-number -The port to bind the DNS tunnel socket to. Must be C<0> on all DNS tunnel -clients and C<53> on the server. +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 + +See gvpe.protocol(7) for a description of the DNS transport +protocol. Avoid this protocol if you can. + +Enable the DNS tunneling protocol on this node, either as server or as +client. Support for this transport protocol is only available when gvpe +was compiled using the C<--enable-dns> option. + +=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 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 RAW IPv4 transport using the C protocol -(default: C). This is the best choice, since the overhead per packet -is only 38 bytes, as opposed to UDP's 58 (or TCP's 60+). +(default: C). =item enable-tcp = yes|true|on | no|false|off +See gvpe.protocol(7) for a description of the TCP transport protocol. + Enable the TCPv4 transport using the C port -(default: C). 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 horribly ineffiecent and -resource-intensive compared to the other transports. +(default: C). Support for this transport protocol is only available +when gvpe was compiled using the C<--enable-tcp> option. =item enable-udp = yes|true|on | no|false|off +See gvpe.protocol(7) for a description of the UDP transport protocol. + Enable the UDPv4 transport using the C port (default: C, 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. +protocol is enabled automatically). NOTE: Please specify C 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 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. + +=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, also known as +"ping-replies"). Other useful values include C<8> (C, a.k.a. +"ping") and C<11> (C), 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 +script in the environment variable C. + =item inherit-tos = yes|true|on | no|false|off Wether to inherit the TOS settings of packets sent to the tunnel when @@ -383,30 +532,54 @@ =item max-retry = positive-number -The maximum interval in seconds (default: C<28800>, 8 hours) between +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. +assure quick reconnections even after longer downtimes. -=item router-priority = 0 | 1 | positive-number>2 +=item max-ttl = seconds -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. +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. -Make sure all hosts always connect (C) to the router -hosts, otherwise connecting to them might be impossible. +=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, above. + +=item router-priority = 0 | 1 | positive-number>=2 + +Sets the router priority of the given node (default: C<0>, disabled). + +If some node tries to connect to another node but it doesn't have a +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 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> -disables routing. The idea behind this is that some hosts can, if -required, bump the C setting to higher than C<1> in their -local config to route through specific hosts. If C is -C<0>, then routing will be refused, so C<1> serves as a "enable, but do -not use by default" switch. +host, but they will never route through it by default (i.e. the config +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 +C setting to higher than C<1> in their local config to +route through specific hosts. If C is C<0>, then routing +will be refused, so C<1> serves as a "enable, but do not use by default" +switch. + +Nodes with C set to C<2> or higher will always be forced +to C = C (unless they are C). =item tcp-port = port-number @@ -453,5 +626,5 @@ =head1 AUTHOR -Marc Lehmann +Marc Lehmann