Provided by: gvpe_3.1-2build3_amd64 bug


       gvpe.conf - configuration file for the GNU VPE daemon


          # global options for all nodes
          udp-port = 407
          mtu = 1492
          ifname = vpn0

          # first node is named branch1 and is at
          node = branch1
          hostname =

          # second node uses dns to resolve the address
          node = branch2
          hostname =
          udp-port = 500       # this host uses a different udp-port

          # third node has no fixed ip address
          node = branch3
          connect = ondemand


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

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

       The only exceptions to the above are the following directives:

       node nodename
           Introduces a node section. The nodename is used to select the right configuration
           section and is the same string as is passed as an argument to the gvpe daemon.

           Multiple node statements with the same node name are supported and will be merged

           This statement switches back to the global section, which is mainly useful if you want
           to include a second config file, e..g for local customisations. To do that, simply
           include this at the very end of your config file:

              include local.conf

       on nodename ...
       on !nodename ...
           You can prefix any configuration directive with on and a nodename. GVPE will will only
           "execute" it on the named node, or (if the nodename starts with !) on all nodes except
           the named one.

           Example: set the MTU to 1450 everywhere, loglevel to noise on branch1, and connect to
           ondemand everywhere but on branch2.

              mtu = 1450
              on branch1 loglevel = noise
              on !branch2 connect = ondemand

       include relative-or-absolute-path
           Reads the specified file (the path must not contain whitespace or = characters) and
           evaluate all config directives in it as if they were spelled out in place of the
           include directive.

           The path is a printf format string, that is, you must escape any % by doubling it, and
           you can have a single %s inside, which will be replaced by the current nodename.

           Relative paths are interpreted relative to the GVPE config directory.

           Example: include the file local.conf in the config directory on every node.

              include local.conf

           Example: include a file conf/nodename.conf

              include conf/%s.conf


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

       Every node that is part of the network must have a section that starts with node =
       nickname. The number and order of the nodes is important 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.


       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
       on), but will affect the behaviour of the gvpe daemon and all connections it creates.

       chroot = path or /
           Tells GVPE to chroot(2) to the specified path after reading all necessary files,
           binding to sockets and running the if-up script, but before running node-up or any
           other scripts.

           The special path / instructs GVPE to create (and remove) an empty temporary directory
           to use as new root. This is most secure, but makes it impossible to use any scripts
           other than the if-up one.

       chuid = numerical-uid
       chgid = numerical-gid
           These two options tell GVPE to change to the given user and/or group id after reading
           all necessary files, binding to sockets and running the if-up script.

           Other scripts, such as node-up, are run with the new user id or group id.

       chuser = username
           Alternative to chuid and chgid: Sets both chuid and chgid to the user and (primary)
           group ids of the specified user (for example, nobody).

       dns-forw-host = hostname/ip
           The DNS server to forward DNS requests to for the DNS tunnel protocol (default:
 , changing it is highly recommended).

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

       dns-case-preserving = yes|true|on | no|false|off
           Sets whether the DNS transport forwarding server preserves case (DNS servers have to,
           but some access systems are even more broken than others) (default: true).

           Normally, when the forwarding server changes the case of domain names then GVPE will
           automatically set this to false.

       dns-max-outstanding = integer-number-of-requests
           The maximum number of outstanding DNS transport requests (default: 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. 3 or even 1) to
           limit the number of parallel requests.

           The default should be working OK for most links.

       dns-overlap-factor = float
           The DNS transport uses the minimum request latency (min_latency) seen during a
           connection as it's timing base. This factor (default: 0.5, must be > 0) is multiplied
           by min_latency to get the maximum sending rate (= minimum send interval), i.e. a
           factor of 1 means that a new request might be generated every min_latency seconds,
           which means on average there should only ever be one outstanding request.  A factor of
           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 1.

           The default should be working OK for most links.

       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 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 0.001 or
           so. For congested or rate-limited links, you might want to go higher, say 0.1, 0.2 or
           even higher.

           The default should be working OK for most links.

       dns-timeout-factor = float
           Factor to multiply the min_latency (see dns-overlap-factor) by to get request
           timeouts. The default of 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. 30). If the link is very
           stable lower values (e.g. 2) might work nicely. Values near or below 1 makes no sense

           The default should be working OK for most links but will result in low throughput if
           packet loss is high.

       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 necessarily up). The following environment variables
           are passed to it (the values are just examples).

           Variables that have the same value on all nodes:

               The configuration base directory.

               The network interface to initialize.

           IFTYPE=native # or tincd
           IFSUBTYPE=linux # or freebsd, darwin etc..
               The interface type (native or 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.

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

               The number of nodes in this GVPE network.

           Variables that are node-specific and with values pertaining to the node running this

               The value of the configuration directive if-up-data.

               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 gvpe.osdep(5) man page for platform-specific

               The nickname of the node.

               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.

           In addition, all node-specific variables (except NODEID) will be available with a
           postfix of _nodeid, which contains the value for that node, e.g. the MAC_1 variable
           contains the MAC address of node #1, while the NODENAME_22 variable contains the name
           of node #22.

           Here is a simple if-up script:

              ip link set $IFNAME up
              [ $NODENAME = branch1 ] && ip addr add dev $IFNAME
              [ $NODENAME = branch2 ] && ip addr add dev $IFNAME
              ip route add dev $IFNAME

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

       ifname = devname
           Sets the tun interface name to the given name. The default is OS-specific and most
           probably something like tun0.

       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 off and do an ifconfig
           down on the device.

       ip-proto = numerical-ip-protocol
           Sets the protocol number to be used for the rawip protocol. This is a 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 firewalls (but
           note that gvpe's rawip protocol is not GRE compatible). Other common choices are 50
           (IPSEC, ESP), 51 (IPSEC, AH), 4 (IPIP tunnels) or 98 (ENCAP, rfc1241).

           Many versions of Linux seem to have a bug that causes them to reorder packets for some
           ip protocols (GRE, ESP) but not for others (AH), so choose wisely (that is, use 51,

       http-proxy-host = hostname/ip
           The http-proxy-* family of options are only available if gvpe was compiled with the
           --enable-http-proxy option and enable tunneling of tcp connections through a http
           proxy server.

           http-proxy-host and http-proxy-port should specify the hostname and port number of the
           proxy server. See 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 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 nodes.


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

       http-proxy-port = proxy-tcp-port
           The port where your proxy server listens.

       http-proxy-auth = login:password
           The optional login and password used to authenticate to the proxy server, separated by
           a literal colon (:). Only basic authentication is currently supported.

       keepalive = seconds
           Sets the keepalive probe interval in seconds (default: 60). After this many seconds of
           inactivity the daemon will start to send keepalive probe every 3 seconds until it
           receives a reply from the other end. If no reply is received within 15 seconds, the
           peer is considered unreachable and the connection is closed.

       loglevel = noise|trace|debug|info|notice|warn|error|critical
           Set the logging level. Connection established messages are logged at level info,
           notable errors are logged with error. Default is info.

       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 if-up script.

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

           This value must be the minimum of the MTU values of all nodes.

       nfmark = integer
           This advanced option, when set to a nonzero value (default: 0), tries to set the
           netfilter mark (or fwmark) value on all sockets gvpe uses to send packets.

           This can be used to make gvpe use a different set of routing rules. For example, on
           GNU/Linux, the if-up could set nfmark to 1000 and then put all routing rules into
           table 99 and then use an ip rule to make gvpe traffic avoid that routing table, in
           effect routing normal traffic via gvpe and gvpe traffic via the normal system routing

              ip rule add not fwmark 1000 lookup 99

       node-up = relative-or-absolute-path
           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 if-up scripts, the following environment
           variables will be set (values are just examples):

               The name of the remote node.

               The node id of the remote node.

               The "socket info" of the target node, protocol dependent but usually in the format

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

           DESTPORT=655 # deprecated
               The protocol port used by the other side, if applicable.

               Node-up scripts get called with STATE=up, node-change scripts get called with
               STATE=change and node-down scripts get called with STATE=down.

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

                echo update delete $ a
                echo update add $ 1 in a $DESTIP
              } | nsupdate -d -k $

       node-change = relative-or-absolute-path
           Same as node-change, but gets called whenever something about a connection changes
           (such as the source IP address).

       node-down = relative-or-absolute-path
           Same as node-up, but gets called whenever a connection is lost.

       pid-file = path
           The path to the pid file to check and create (default: LOCALSTATEDIR/run/
           The first %s is replaced by the nodename - any other use of % must be written as %%.

       private-key = relative-path-to-key
           Sets the path (relative to the config directory) to the private key (default:
           hostkey). This is a printf format string so every % must be doubled. A single %s is
           replaced by the hostname, so you could use paths like hostkeys/%s to be able to share
           the same config directory between nodes.

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

       rekey = seconds
           Sets the rekeying interval in seconds (default: 3607). Connections are reestablished
           every rekey seconds, making them use a new encryption key.

       seed-device = path
           The random device used to initially and regularly seed the random number generator
           (default: /dev/urandom). Randomness is of paramount importance to the security of the
           algorithms used in gvpe.

           On program start and every seed-interval, gvpe will read 64 octets.

           Setting this path to the empty string will disable this functionality completely (the
           underlying crypto library will likely look for entropy sources on it's own though, so
           not all is lost).

       seed-interval = seconds
           The number of seconds between reseeds of the random number generator (default: 3613).
           A value of 0 disables this regular reseeding.

       serial = string
           The configuration serial number. This can be any string up to 16 bytes length. Only
           when the serial matches on both sides of a connection will the connection succeed.
           This is not a security mechanism and eay to spoof, this mechanism exists to alert
           users that their config is outdated.

           It's recommended to specify this is a date string such as 2013-05-05 or

           The exact algorithm is as this: if a connection request is received form a node with
           an identical serial, then it succeeds normally.

           If the remote serial is lower than the local serial, it is ignored.

           If the remote serial is higher than the local serial, a warning message is logged.

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

       allow-direct = nodename
           Allow direct connections to this node. See deny-direct for more info.

       compress = yes|true|on | no|false|off
           For the current node, this specified whether it will accept compressed packets, and
           for all other nodes, this specifies whether to try to compress data packets sent to
           this node (default: yes). Compression is really cheap even on slow computers, has no
           size overhead at all and will only be used when the other side supports compression,
           so enabling this is often a good idea.

       connect = ondemand | never | always | disabled
           Sets the connect mode (default: always). It can be always (always try to establish and
           keep a connection to the given node), never (never initiate a connection to the given
           host, but accept connections), ondemand (try to establish a connection when there are
           outstanding packets in the queue and take it down after the keepalive interval) or
           disabled (node is bad, don't talk to it).

           Routers will automatically be forced to always unless they are disabled, to ensure all
           nodes can talk to each other.

       deny-direct = nodename | *
           Deny direct connections to the specified node (or all nodes when * is given). Only one
           node can be specified, but you can use multiple allow-direct and 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 deny-direct = * and
           allow-direct = othernodename (the other node 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 allow-direct? If yes, allow the connection.

           2. Other node mentioned in a deny-direct? If yes, deny direct connections.

           3. Allow the connection.

           That is, allow-direct takes precedence over 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.

       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 dns-hostname, i.e.

              dns-domainname =
              dns-hostname   =

           Corresponds to the following DNS entries in the domain:


       dns-hostname = hostname/ip
           The address to bind the DNS tunnel socket to, similar to the hostname, but for the DNS
           tunnel protocol only. Default:, but that might change.

       dns-port = port-number
           The port to bind the DNS tunnel socket to. Must be 53 on DNS tunnel servers.

       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
           --enable-dns option.

       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 icmp-type on this node.

       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 ip-proto protocol (default: no).

       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 tcp-port port (default: no). Support for this
           transport protocol is only available when gvpe was compiled using the --enable-tcp

       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 udp-port port (default: no).

       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.

       icmp-type = integer
           Sets the type value to be used for outgoing (and incoming) packets sent via the ICMP

           The default is 0 (which is echo-reply, also known as "ping-reply"). Other useful
           values include 8 (echo-request, a.k.a.  "ping") and 11 (time-exceeded), but any 8-bit
           value can be used.

       if-up-data = value
           The value specified using this directive will be passed to the if-up script in the
           environment variable IFUPDATA.

       inherit-tos = yes|true|on | no|false|off
           Whether to inherit the TOS settings of packets sent to the tunnel when sending packets
           to this node (default: yes). If set to yes then outgoing tunnel packets will have the
           same TOS setting as the packets sent to the tunnel device, which is usually what you

       low-power = yes|true|on | no|false|off
           If true, designates a node as a low-power node. Low-power nodes use larger timeouts
           and try to reduce cpu time. Other nodes talking to a low-power node will also use
           larger timeouts, and will use less aggressive optimisations, in the hope of reducing
           load. Security is not compromised.

           The typical low-power node would be a mobile phone, where wakeups and encryption can
           significantly increase power drain.

       max-retry = positive-number
           The maximum interval in seconds (default: 3600, one hour) between retries to establish
           a connection to this node. When a connection cannot 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. 120) on connections to routers that usually are stable but sometimes
           are down, to assure quick reconnections even after longer downtimes.

       max-ttl = seconds
           Expire packets that couldn't be sent after this many seconds (default: 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.

       max-queue = positive-number>=1
           The maximum number of packets that will be queued (default: 512) for this node. If
           more packets are sent then earlier packets will be expired. See max-ttl, above.

       router-priority = 0 | 1 | positive-number>=2
           Sets the router priority of the given node (default: 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 1 that is currently reachable. This is called a mediated
           connection, as the connection itself will still be direct, but it uses another node to
           mediate between the two nodes.

           The value 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 1 allows other hosts to route through the router 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 router-priority
           setting to higher than 1 in their local config to route through specific hosts. If
           router-priority is 0, then routing will be refused, so 1 serves as a "enable, but do
           not use by default" switch.

           Nodes with router-priority set to 2 or higher will always be forced to connect =
           always (unless they are disabled).

       tcp-port = port-number
           Similar to udp-port (default: 655), but sets the TCP port number.

       udp-port = port-number
           Sets the port number used by the UDP protocol (default: 655, not officially assigned
           by IANA!).


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

           The config file.

           The if-up script

       node-up, node-down
           If used the node up or node-down scripts.

           The (default path of the) private key of the current host.

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


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


       Marc Lehmann <>