GVPE.OSDEP(5)

✨ gvpe.osdep — os dependent info ✨

okay bestie, welcome to gvpe.osdep(5) from the GNU Virtual Private Ethernet manual 💖 this is the page where we spill all the tea about how gvpe behaves on different operating systems. buckle up 🎀

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🌸 NAME 🌸

gvpe.osdep — os dependent information

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💫 DESCRIPTION 💫

this file is literally just here to capture all the OS-dependent config and build drama, the quirks, and the platform limitations that we know about. it's giving "we tried our best on every platform" energy fr fr 🙈

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🦋 TUN vs. TAP interface 🦋

so most operating systems nowadays come with something called a tunnel-device, and it lets you divert IPv4 (and often other protocols too, bestie, we're not just IPv4 girlies) into a user space daemon like gvpe. this is what everyone calls a TUN-device. slay.

that's totally fine for point-to-point tunnels, but for a virtual ethernet, you need an extra ethernet header on top. that functionality (we call it a TAP device around here) is only provided by a subset of the configurations. not everyone got the upgrade 😭

on platforms that only support a TUN-device, gvpe will invoke its magical ethernet emulation package ✨ which currently only handles ARP requests for the IPv4 protocol (more could be added, but the tincd network drivers might need to be modified for this to work). so on those platforms, only IPv4 will be supported. periodt.

also, since there is (currently) no way to tell gvpe which IP subnets live on a specific host, you've got two options, bestie, pick your fighter:

• hardwire the MAC address for TUN-style hosts on all networks (and avoid ARP altogether, which is possible), or
• send a packet from these hosts into the vpn network to tell gvpe the local interface address.

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🧚 Interface Initialisation 🧚

unless otherwise noted, 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. no /sbin/ifconfig, no vibes 💅

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👑 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. main character energy, honestly 👑

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. that's it, that's the whole task 💖

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; might work for many bsd variants. it's giving "we'll see" 😭

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. do not skip it bestie, it's load-bearing 🫶

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. (bestie, read the room, use the native one 💅)

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. help a girl out 🙏

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.

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💖 SEE ALSO 💖

gvpe(5).

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✨ AUTHOR ✨

Marc Lehmann <gvpe@schmorp.de>

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that's the whole page bestie, you ate it up 👑 go forth and configure your interfaces 💅

this was version 3.1, dated 2018-10-25 — the GVPE.OSDEP(5) page from GNU Virtual Private Ethernet. mwah, bye 🫶