From: Maximilian Wilhelm <max@sdn.clinic> Signed-off-by: Maximilian Wilhelm <max@sdn.clinic> --- doc/man-sections/vrf.rst | 75 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 75 insertions(+) create mode 100644 doc/man-sections/vrf.rst
diff --git a/doc/man-sections/vrf.rst b/doc/man-sections/vrf.rst new file mode 100644 index 0000000..f395db1 --- /dev/null +++ b/doc/man-sections/vrf.rst @@ -0,0 +1,75 @@ +Virtual Routing and Forwarding +--------------------------------------- + +Options in this section relates to configuration of virtual routing and +forwarding in combination with the underlying operating system. + +As of today this is only supported on Linux, a kernel >= 4.9 is recommended. + +This could come in handy when for example the external network should be only +used as a means to connect to some VPN endpoints and all regular traffic +should only be routed through any tunnel(s). +This could be achieved by setting up a VRF and configuring the interface +connected to the external network to be part of the VRF. The examples below +will cover this setup. + +Another option would be to put the tun/tap interface into a VRF. This could +be done by an up-script which uses the `ip link set` command shown below. + + +**VRF setup with iproute2** + +Create VRF `vrf_external` and map it to routing table `1023` + +:: + + ip link add vrf_external type vrf table 1023 + +Move `eth0` into `vrf_external` + +:: + + ip link set master vrf_external dev eth0 + +Any prefixes configured on `eth0` will be moved from the `main` routing +table into routing table `1023` + + +**VRF setup with ifupdown** + +For Debian based Distributions `ifupdown2` provides an almost drop-in +replacement for `ifupdown` including VRFs and other features. +A configuration for an interface `eth0` being part of VRF `vrf_external` +could look like this: + +:: + + auto eth0 + iface eth0 + address 192.0.2.42/24 + address 2001:db8:08:15::42/64 + gateway 192.0.2.1 + gateway 2001:db8:08:15::1 + vrf vrf_external + + auto vrf_external + iface vrf_external + vrf-table 1023 + + +**OpenVPN config** + +--bind-dev device + Set the device to bind the server socket to to the VRF + + --bind-dev vrf_external + + +**Further reading** + +Wikipedia has nice page one VRFs: https://en.wikipedia.org/wiki/Virtual_routing_and_forwarding + +This talk from the Network Track of FrOSCon 2018 provides an overview about +advanced layer 2 and layer 3 features of Linux + - Slides: https://www.slideshare.net/BarbarossaTM/l2l3-fr-fortgeschrittene-helle-und-dunkle-magie-im-linuxnetzwerkstack + - Video (german): https://media.ccc.de/v/froscon2018-2247-l2_l3_fur_fortgeschrittene_-_helle_und_dunkle_magie_im_linux-netzwerkstack -- 2.1.4 _______________________________________________ Openvpn-devel mailing list Openvpn-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/openvpn-devel
