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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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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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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 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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To configure the interface, use either iproute2: |
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ip set $IFNAME address $MAC mtu $MTU up |
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ip addr add $IFNAME 10.11.12.13 |
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ip route add $IFNAME 10.11.12.13/8 |
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Or C<ifconfig>: |
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ifconfig $IFNAME hw ether $MAC mtu $MTU |
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ifconfig $IFNAME 10.11.12.13 netmask 255.0.0.0 |
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To hardwire ARP addresses, use iproute2 (C<arp> can do it, too): |
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MAC=fe:fd:80:00:00:$(printf "%02x" $NODEID) |
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ip neighbour add 10.11.12.13 lladdr $MAC nud permanent dev $IFNAME |
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=head2 tincd/linux |
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TAP-device; already part of the kernel (2.2+ supported). See |
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C<native/linux> for more info. |
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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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The MAC need not be set (and in fact I<cannot> be set). The MAC address |
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is dynamically being patched into packets and ARP-requests, so only IPv4 |
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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). To initialize |
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the interface, use this command: |
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ifconfig $IFNAME ether $MAC mtu $MTU up |
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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 such, giving it an address on your |
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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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=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 tincd/darwin |
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TUN-device; See C<tincd/netbsd> for more information. |
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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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A newer (and reportedly much more stable) driver that also supports TAP |
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operations is available here: |
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http://www-user.rhrk.uni-kl.de/~nissler/tuntap/ |
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But GVPE has not been ported to it's TAP interface. Patches are welcome. |
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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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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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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>), which should probably not |
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be configured in any way, except for setting it I<up>. |
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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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=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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Marc Lehmann <gvpe@plan9.de> |
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