Provided by: gvpe_2.24-2_i386 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

       The only exception to the above is the "on" directive that can prefix
       any 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.

       For 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

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


       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


       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.

       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-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 whatsoever.

           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 GVPE:

               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 information.

               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, AH).

       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

       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

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

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

       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.

       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

               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 protocol/ip:port.

               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:

       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 fetch the files at the location where
           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-node to avoid spoofing,
           it is not recommended to use this feature.

       rekey = seconds
           Sets the rekeying interval in seconds (default: 3600). Connections
           are reestablished every rekey seconds, making them use a new
           encryption key.

       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 tables:

              ip rule add not fwmark 1000 lookup 99

       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 node.

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

       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

           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

           1. Other node mentioned in an allow-direct? If yes, allow the

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

           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

           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

       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

           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

           Enable the RAW IPv4 transport using the ip-proto protocol (default:

       enable-tcp = yes|true|on | no|false|off
           See gvpe.protocol(7) for a description of the TCP transport

           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 option.

       enable-udp = yes|true|on | no|false|off
           See gvpe.protocol(7) for a description of the UDP transport

           Enable the UDPv4 transport using the udp-port port (default: no,
           unless no other protocol is enabled for a node, in which case this
           protocol is enabled automatically).

           NOTE: Please specify 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.

       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 transport.

           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 want.

       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

       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

           The config file.

           The if-up script

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

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

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


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


       Marc Lehmann <>