NAME

       gvpe.osdep - os dependent information

DESCRIPTION

       This file tries to capture OS-dependent configuration or build issues, quirks and platform
       limitations, as known.

TUN vs. TAP interface

       Most operating systems nowadays support something called a tunnel-device, which makes it
       possible to divert IPv4 (and often other protocols, too) into a user space daemon like
       gvpe. This is being referred to as a TUN-device.

       This is fine for point-to-point tunnels, but for a virtual ethernet, an additional
       ethernet header is needed. This functionality (called a TAP device here) is only provided
       by a subset of the configurations.

       On platforms only supporting a TUN-device, gvpe will invoke it's magical ethernet
       emulation package, which currently only handles ARP requests for the IPv4 protocol (but
       more could be added, bu the tincd network drivers might need to be modified for this to
       work). This means that on those platforms, only IPv4 will be supported.

       Also, since there is no way (currently) to tell gvpe which IP subnets are found on a
       specific host, you will either need to hardwire the MAC address for TUN-style hosts on all
       networks (and avoid ARP altogether, which is possible), or you need to send a packet from
       these hosts into the vpn network to tell gvpe the local interface address.

Interface Initialisation

       Unless otherwise notes, the network interface will be initialized with the expected MAC
       address and correct MTU value. With most interface drivers, this is done by running
       /sbin/ifconfig, so make sure that this command exists.

Interface Types

       native/linux

       TAP-device; already part of the kernel (only 2.4+ supported, but see tincd/linux). This is
       the configuration tested best, as gvpe is being developed on this platform.

       ifname should be set to the name of the network device.

       To hardwire ARP addresses, use iproute2 (arp can do it, too):

         MAC=fe:fd:80:00:00:$(printf "%02x" $NODEID)
         ip neighbour add 10.11.12.13 lladdr $MAC nud permanent dev $IFNAME

       tincd/linux

       TAP-device; already part of the kernel (2.2 only). See native/linux for more info.

       ifname should be set to the path of a tap device, e.g. /dev/tap0. The interface will be
       named accordingly.

       native/cygwin

       TAP-device; The TAP device to be used must either be the CIPE driver
       (http://cipe-win32.sourceforge.net/), or (highly recommended) the newer TAP-Win32 driver
       bundled with openvpn (http://openvpn.sf.net/). Just download and run the openvpn
       installer. The only option you need to select is the TAP driver.

       ifname should be set to the name of the device, found in the registry at (no kidding :):

             HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Network\{4D36E972-E325-11CE-BFC1-08002BE10318}\<adapterid>\Connection\Name

       The MAC address is dynamically being patched into packets and ARP-requests, so only IPv4
       works with ARP on this platform.

       tincd/bsd

       TAP-device, maybe; migth work for many bsd variants.

       This driver is a newer version of the tincd/*bsd drivers. It might provide a TAP device,
       or might not work at all. You might try this interface type first, and, if it doesn't
       work, try one of the OS-specific drivers.

       tincd/freebsd

       TAP-device; part of the kernel (since 4.x, maybe earlier).

       ifname should be set to the path of a tap device, e.g. /dev/tap0. The interface will be
       named accordingly.

       These commands might be helpful examples:

         ifconfig $IFNAME 10.0.0.$NODEID
         route add -net 10.0.0.0 -netmask 255.255.255.0 -interface $IFNAME 10.0.0.$NODEID

       tincd/netbsd

       TUN-device; The interface is a point-to-point device. To initialize it, you currently need
       to configure it as a point-to-point device, giving it an address on your vpn (the exact
       address doesn't matter), like this:

         ifconfig $IFNAME mtu $MTU up
         ifconfig $IFNAME 10.11.12.13 10.55.66.77
         route add -net 10.0.0.0 10.55.66.77 255.0.0.0
         ping -c1 10.55.66.77 # ping once to tell gvpe your gw ip

       The ping is required to tell the ARP emulator inside GVPE the local IP address.

       ifname should be set to the path of a tun device, e.g. /dev/tun0. The interface will be
       named accordingly.

       tincd/openbsd

       TUN-device; already part of the kernel. See tincd/netbsd for more information.

       native/darwin

       TAP-device;

       The necessary kernel extension can be found here:

         http://www-user.rhrk.uni-kl.de/~nissler/tuntap/

       There are two drivers, the one to use is the "tap" driver. It driver must be loaded before
       use, read the docs on how to install it as a startup item.

       ifname should be set to the path of a tap device, e.g. /dev/tap0. The interface will be
       named accordingly.

       These commands might be helpful examples:

         ifconfig $IFNAME 10.0.0.$NODEID
         route add -net 10.0.0.0 -interface $IFNAME 255.255.255.0

       tincd/darwin

       TUN-device; See tincd/netbsd for more information. native/darwin is preferable.

       The necessary kernel extension can be found here:

         http://chrisp.de/en/projects/tunnel.html

       ifname should be set to the path of a tun device, e.g. /dev/tun0. The interface will be
       named accordingly.

       The driver must be loaded before use:

         kmodload tunnel

       tincd/solaris

       TUN-device; already part of the kernel(?), or available here:

         http://vtun.sourceforge.net/tun/

       Some precompiled tun drivers might be available here:

         http://www.monkey.org/~dugsong/fragroute/

       The interface MAC and MTU are NOT set up for you. Please try it out and send me an
       ifconfig command invocation that does that.

       See tincd/netbsd for more information.

       Completely untested so far.

       tincd/mingw

       TAP-device; see native/cygwin for more information.

       The setup is likely to be similar to native/cygwin.

       Completely untested so far.

       tincd/raw_socket

       TAP-device; purpose unknown and untested, probably binds itself on an existing ethernet
       device (given by ifname). It must be down prior to running the command, and GVPE will try
       to set it's MAC address and MTU to the "correct" values.

       Completely untested so far.

       tincd/uml_socket

       TAP-device; purpose unknown and untested, probably creates a UNIX datagram socket (path
       given by ifname) and reads and writes raw packets, so might be useful in other than UML
       contexts.

       No network interface is created, and the MAC and MTU must be set as appropriate on the
       other side of the socket.  GVPE will exit if the MAC address doesn't match what it
       expects.

       Completely untested so far.

       tincd/cygwin

       Known to be broken, use native/cygwin instead.

SEE ALSO

       gvpe(5).

AUTHOR

       Marc Lehmann <gvpe@schmorp.de>