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=head1 NAME |
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gvpe.osdep - os dependent information |
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=head1 DESCRIPTION |
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This file tries to capture OS-dependent configuration or build issues, |
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quirks and platform limitations, as known. |
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=head2 TUN vs. TAP interface |
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Most operating systems nowadays support something called a |
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I<tunnel>-device, which makes it possible to divert IPv4 (and often other |
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protocols, too) into a userspace daemon like C<gvpe>. This is being |
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referred to as a TUN-device. |
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|
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This is fine for point-to-point tunnels, but for a virtual ethernet, an |
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additional ethernet header is needed. This functionality (called a TAP |
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device here) is only provided by a subset of the configurations. |
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|
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On platforms only supporting a TUN-device, gvpe will invoke it's magical |
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ethernet emulation package, which currently only handles ARP requests for |
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the IPv4 protocol (but more could be added, bu the tincd network drivers |
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might need to be modified for this to work). This means that on those |
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platforms, only IPv4 will be supported. |
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Also, since there is no way (currently) to tell gvpe which IP subnets are |
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found on a specific host, you will either need to hardwire the MAC address |
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for TUN-style hosts on all networks (and avoid ARP altogether, which is |
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possible), or you need to send a packet from these hosts into the vpn |
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network to tell gvpe the local interface address. |
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=head2 Interface Initialisation |
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|
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Unless otherwise notes, the network interface will be set "UP" with the |
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correct MAC address and correct MTU value. With most interface drivers, |
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this is done by running C</sbin/ifconfig>, so make sure that this command |
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exists. |
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=head2 native/linux |
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TAP-device; already part of the kernel (only 2.4+ supported, but see |
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tincd/linux). This is the configuration tested best, as gvpe is being |
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developed on this platform. |
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|
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C<ifname> should be set to the name of the network device. |
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To hardwire ARP addresses, use iproute2 (C<arp> can do it, too): |
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MAC=fe:fd:80:00:00:$(printf "%02x" $NODEID) |
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ip neighbour add 10.11.12.13 lladdr $MAC nud permanent dev $IFNAME |
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|
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=head2 tincd/linux |
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TAP-device; already part of the kernel (2.2 only). See |
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C<native/linux> for more info. |
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C<ifname> should be set to the path of a tap device, |
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e.g. C</dev/tap0>. The interface will be named accordingly. |
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|
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=head2 native/cygwin |
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TAP-device; The TAP device to be used must either be the CIPE driver |
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(C<http://cipe-win32.sourceforge.net/>), or (highly recommended) the newer |
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TAP-Win32 driver bundled with openvpn (http://openvpn.sf.net/). Just |
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download and run the openvpn installer. The only option you need to select |
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is the TAP driver. |
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|
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C<ifname> should be set to the name of the device, found in the registry |
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at (no kidding :): |
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HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Network\{4D36E972-E325-11CE-BFC1-08002BE10318}\<adapterid>\Connection\Name |
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The MAC address is dynamically being patched into packets and |
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ARP-requests, so only IPv4 works with ARP on this platform. |
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=head2 tincd/freebsd |
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TAP-device; part of the kernel (since 4.x, maybe earlier). |
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C<ifname> should be set to the path of a tap device, |
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e.g. C</dev/tap0>. The interface will be named accordingly. |
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These commands might be helpful examples: |
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ifconfig $IFNAME 10.0.0.$NODEID |
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route add -net 10.0.0.0 -netmask 255.255.255.0 -interface $IFNAME 10.0.0.$NODEID |
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=head2 tincd/netbsd |
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TUN-device; The interface is a point-to-point device. To initialize it, |
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you currently need to configure it as a point-to-point device, giving it |
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an address on your vpn (the exact address doesn't matter), like this: |
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ifconfig $IFNAME mtu $MTU up |
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ifconfig $IFNAME 10.11.12.13 10.55.66.77 |
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route add -net 10.0.0.0 10.55.66.77 255.0.0.0 |
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ping -c1 10.55.66.77 # ping once to tell gvpe your gw ip |
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The ping is required to tell the ARP emulator inside GVPE the local IP |
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address. |
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C<ifname> should be set to the path of a tun device, |
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e.g. C</dev/tun0>. The interface will be named accordingly. |
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=head2 tincd/openbsd |
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TUN-device; already part of the kernel. See C<tincd/netbsd> for more information. |
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=head2 native/darwin |
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TAP-device; |
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The necessary kernel extension can be found here: |
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http://www-user.rhrk.uni-kl.de/~nissler/tuntap/ |
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There are two drivers, the one to use is the "tap" driver. It driver must |
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be loaded before use, read the docs on how to install it as a startup |
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item. |
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|
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C<ifname> should be set to the path of a tap device, |
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e.g. C</dev/tap0>. The interface will be named accordingly. |
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|
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These commands might be helpful examples: |
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ifconfig $IFNAME 10.0.0.$NODEID |
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route add -net 10.0.0.0 -interface $IFNAME 255.255.255.0 |
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=head2 tincd/darwin |
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TUN-device; See C<tincd/netbsd> for more information. C<native/darwin> is |
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preferable. |
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The necessary kernel extension can be found here: |
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http://chrisp.de/en/projects/tunnel.html |
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C<ifname> should be set to the path of a tun device, |
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e.g. C</dev/tun0>. The interface will be named accordingly. |
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The driver must be loaded before use: |
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kmodload tunnel |
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=head2 tincd/solaris |
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TUN-device; already part of the kernel(?), or available here: |
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http://vtun.sourceforge.net/tun/ |
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Some precompiled tun drivers might be available here: |
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http://www.monkey.org/~dugsong/fragroute/ |
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The interface MAC and MTU are I<NOT> set up for you. Please try it out and |
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send me an C<ifconfig> command invocation that does that. |
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See C<tincd/netbsd> for more information. |
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Completely unstested so far. |
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=head2 tincd/mingw |
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TAP-device; see C<native/cygwin> for more information. |
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The setup is likely to be similar to C<native/cygwin>. |
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Completely untested so far. |
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=head2 tincd/raw_socket |
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TAP-device; purpose unknown and untested, probably binds itself on an |
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existing ethernet device (given by C<ifname>). It must be down prior to |
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running the command, and GVPE will try to set it's MAC address and MTU to |
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the "correct" values. |
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Completely untested so far. |
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=head2 tincd/uml_socket |
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TAP-device; purpose unknown and untested, probably creates a unix datagram |
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socket (path given by C<ifname>) and reads and writes raw packets, so |
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might be useful in other than UML contexts. |
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No network interface is created, and the MAC and MTU must be set as |
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approriate on the other side of the socket. GVPE will exit if the MAC |
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address doesn't match what it expects. |
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Completely untested so far. |
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=head2 tincd/cygwin |
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Known to be broken, use C<native/cygwin> instead. |
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=head1 SEE ALSO |
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gvpe(5). |
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=head1 AUTHOR |
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|
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Marc Lehmann <gvpe@plan9.de> |
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|
