precedence over the VRF device rules directing specific traffic as desired.
In addition, VRF devices allow VRFs to be nested within namespaces. For
-example network namespaces provide separation of network interfaces at L1
-(Layer 1 separation), VLANs on the interfaces within a namespace provide
-L2 separation and then VRF devices provide L3 separation.
+example network namespaces provide separation of network interfaces at the
+device layer, VLANs on the interfaces within a namespace provide L2 separation
+and then VRF devices provide L3 separation.
Design
------
+------+ +------+
Packets received on an enslaved device and are switched to the VRF device
-using an rx_handler which gives the impression that packets flow through
-the VRF device. Similarly on egress routing rules are used to send packets
-to the VRF device driver before getting sent out the actual interface. This
-allows tcpdump on a VRF device to capture all packets into and out of the
-VRF as a whole.[1] Similarly, netfilter [2] and tc rules can be applied
-using the VRF device to specify rules that apply to the VRF domain as a whole.
+in the IPv4 and IPv6 processing stacks giving the impression that packets
+flow through the VRF device. Similarly on egress routing rules are used to
+send packets to the VRF device driver before getting sent out the actual
+interface. This allows tcpdump on a VRF device to capture all packets into
+and out of the VRF as a whole.[1] Similarly, netfilter[2] and tc rules can be
+applied using the VRF device to specify rules that apply to the VRF domain
+as a whole.
[1] Packets in the forwarded state do not flow through the device, so those
packets are not seen by tcpdump. Will revisit this limitation in a
future release.
-[2] Iptables on ingress is limited to NF_INET_PRE_ROUTING only with skb->dev
- set to real ingress device and egress is limited to NF_INET_POST_ROUTING.
- Will revisit this limitation in a future release.
-
+[2] Iptables on ingress supports PREROUTING with skb->dev set to the real
+ ingress device and both INPUT and PREROUTING rules with skb->dev set to
+ the VRF device. For egress POSTROUTING and OUTPUT rules can be written
+ using either the VRF device or real egress device.
Setup
-----
e.g, ip link add vrf-blue type vrf table 10
ip link set dev vrf-blue up
-2. Rules are added that send lookups to the associated FIB table when the
- iif or oif is the VRF device. e.g.,
+2. An l3mdev FIB rule directs lookups to the table associated with the device.
+ A single l3mdev rule is sufficient for all VRFs. The VRF device adds the
+ l3mdev rule for IPv4 and IPv6 when the first device is created with a
+ default preference of 1000. Users may delete the rule if desired and add
+ with a different priority or install per-VRF rules.
+
+ Prior to the v4.8 kernel iif and oif rules are needed for each VRF device:
ip ru add oif vrf-blue table 10
ip ru add iif vrf-blue table 10
- Set the default route for the table (and hence default route for the VRF).
- e.g, ip route add table 10 prohibit default
+3. Set the default route for the table (and hence default route for the VRF).
+ ip route add table 10 unreachable default
-3. Enslave L3 interfaces to a VRF device.
- e.g, ip link set dev eth1 master vrf-blue
+4. Enslave L3 interfaces to a VRF device.
+ ip link set dev eth1 master vrf-blue
Local and connected routes for enslaved devices are automatically moved to
the table associated with VRF device. Any additional routes depending on
- the enslaved device will need to be reinserted following the enslavement.
+ the enslaved device are dropped and will need to be reinserted to the VRF
+ FIB table following the enslavement.
+
+ The IPv6 sysctl option keep_addr_on_down can be enabled to keep IPv6 global
+ addresses as VRF enslavement changes.
+ sysctl -w net.ipv6.conf.all.keep_addr_on_down=1
-4. Additional VRF routes are added to associated table.
- e.g., ip route add table 10 ...
+5. Additional VRF routes are added to associated table.
+ ip route add table 10 ...
Applications
or to specify the output device using cmsg and IP_PKTINFO.
+TCP services running in the default VRF context (ie., not bound to any VRF
+device) can work across all VRF domains by enabling the tcp_l3mdev_accept
+sysctl option:
+ sysctl -w net.ipv4.tcp_l3mdev_accept=1
-Limitations
------------
-Index of original ingress interface is not available via cmsg. Will address
-soon.
+netfilter rules on the VRF device can be used to limit access to services
+running in the default VRF context as well.
+
+The default VRF does not have limited scope with respect to port bindings.
+That is, if a process does a wildcard bind to a port in the default VRF it
+owns the port across all VRF domains within the network namespace.
################################################################################
Using iproute2 for VRFs
=======================
-VRF devices do *not* have to start with 'vrf-'. That is a convention used here
-for emphasis of the device type, similar to use of 'br' in bridge names.
+iproute2 supports the vrf keyword as of v4.7. For backwards compatibility this
+section lists both commands where appropriate -- with the vrf keyword and the
+older form without it.
1. Create a VRF
To instantiate a VRF device and associate it with a table:
$ ip link add dev NAME type vrf table ID
- Remember to add the ip rules as well:
- $ ip ru add oif NAME table 10
- $ ip ru add iif NAME table 10
- $ ip -6 ru add oif NAME table 10
- $ ip -6 ru add iif NAME table 10
-
- Without the rules route lookups are not directed to the table.
-
- For example:
- $ ip link add dev vrf-blue type vrf table 10
- $ ip ru add pref 200 oif vrf-blue table 10
- $ ip ru add pref 200 iif vrf-blue table 10
- $ ip -6 ru add pref 200 oif vrf-blue table 10
- $ ip -6 ru add pref 200 iif vrf-blue table 10
-
+ As of v4.8 the kernel supports the l3mdev FIB rule where a single rule
+ covers all VRFs. The l3mdev rule is created for IPv4 and IPv6 on first
+ device create.
2. List VRFs
For example:
$ ip -d link show type vrf
- 11: vrf-mgmt: <NOARP,MASTER,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
+ 11: mgmt: <NOARP,MASTER,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
link/ether 72:b3:ba:91:e2:24 brd ff:ff:ff:ff:ff:ff promiscuity 0
vrf table 1 addrgenmode eui64
- 12: vrf-red: <NOARP,MASTER,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
+ 12: red: <NOARP,MASTER,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
link/ether b6:6f:6e:f6:da:73 brd ff:ff:ff:ff:ff:ff promiscuity 0
vrf table 10 addrgenmode eui64
- 13: vrf-blue: <NOARP,MASTER,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
+ 13: blue: <NOARP,MASTER,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
link/ether 36:62:e8:7d:bb:8c brd ff:ff:ff:ff:ff:ff promiscuity 0
vrf table 66 addrgenmode eui64
- 14: vrf-green: <NOARP,MASTER,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
+ 14: green: <NOARP,MASTER,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
link/ether e6:28:b8:63:70:bb brd ff:ff:ff:ff:ff:ff promiscuity 0
vrf table 81 addrgenmode eui64
Or in brief output:
$ ip -br link show type vrf
- vrf-mgmt UP 72:b3:ba:91:e2:24 <NOARP,MASTER,UP,LOWER_UP>
- vrf-red UP b6:6f:6e:f6:da:73 <NOARP,MASTER,UP,LOWER_UP>
- vrf-blue UP 36:62:e8:7d:bb:8c <NOARP,MASTER,UP,LOWER_UP>
- vrf-green UP e6:28:b8:63:70:bb <NOARP,MASTER,UP,LOWER_UP>
+ mgmt UP 72:b3:ba:91:e2:24 <NOARP,MASTER,UP,LOWER_UP>
+ red UP b6:6f:6e:f6:da:73 <NOARP,MASTER,UP,LOWER_UP>
+ blue UP 36:62:e8:7d:bb:8c <NOARP,MASTER,UP,LOWER_UP>
+ green UP e6:28:b8:63:70:bb <NOARP,MASTER,UP,LOWER_UP>
3. Assign a Network Interface to a VRF
Network interfaces are assigned to a VRF by enslaving the netdevice to a
VRF device:
- $ ip link set dev NAME master VRF-NAME
+ $ ip link set dev NAME master NAME
On enslavement connected and local routes are automatically moved to the
table associated with the VRF device.
For example:
- $ ip link set dev eth0 master vrf-mgmt
+ $ ip link set dev eth0 master mgmt
4. Show Devices Assigned to a VRF
To show devices that have been assigned to a specific VRF add the master
option to the ip command:
- $ ip link show master VRF-NAME
+ $ ip link show vrf NAME
+ $ ip link show master NAME
For example:
- $ ip link show master vrf-red
- 3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master vrf-red state UP mode DEFAULT group default qlen 1000
+ $ ip link show vrf red
+ 3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master red state UP mode DEFAULT group default qlen 1000
link/ether 02:00:00:00:02:02 brd ff:ff:ff:ff:ff:ff
- 4: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master vrf-red state UP mode DEFAULT group default qlen 1000
+ 4: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master red state UP mode DEFAULT group default qlen 1000
link/ether 02:00:00:00:02:03 brd ff:ff:ff:ff:ff:ff
- 7: eth5: <BROADCAST,MULTICAST> mtu 1500 qdisc noop master vrf-red state DOWN mode DEFAULT group default qlen 1000
+ 7: eth5: <BROADCAST,MULTICAST> mtu 1500 qdisc noop master red state DOWN mode DEFAULT group default qlen 1000
link/ether 02:00:00:00:02:06 brd ff:ff:ff:ff:ff:ff
Or using the brief output:
- $ ip -br link show master vrf-red
+ $ ip -br link show master red
eth1 UP 02:00:00:00:02:02 <BROADCAST,MULTICAST,UP,LOWER_UP>
eth2 UP 02:00:00:00:02:03 <BROADCAST,MULTICAST,UP,LOWER_UP>
eth5 DOWN 02:00:00:00:02:06 <BROADCAST,MULTICAST>
To list neighbor entries associated with devices enslaved to a VRF device
add the master option to the ip command:
- $ ip [-6] neigh show master VRF-NAME
+ $ ip [-6] neigh show vrf NAME
+ $ ip [-6] neigh show master NAME
For example:
- $ ip neigh show master vrf-red
+ $ ip neigh show vrf red
10.2.1.254 dev eth1 lladdr a6:d9:c7:4f:06:23 REACHABLE
10.2.2.254 dev eth2 lladdr 5e:54:01:6a:ee:80 REACHABLE
- $ ip -6 neigh show master vrf-red
+ $ ip -6 neigh show vrf red
2002:1::64 dev eth1 lladdr a6:d9:c7:4f:06:23 REACHABLE
To show addresses for interfaces associated with a VRF add the master
option to the ip command:
- $ ip addr show master VRF-NAME
+ $ ip addr show vrf NAME
+ $ ip addr show master NAME
For example:
- $ ip addr show master vrf-red
- 3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master vrf-red state UP group default qlen 1000
+ $ ip addr show vrf red
+ 3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master red state UP group default qlen 1000
link/ether 02:00:00:00:02:02 brd ff:ff:ff:ff:ff:ff
inet 10.2.1.2/24 brd 10.2.1.255 scope global eth1
valid_lft forever preferred_lft forever
valid_lft forever preferred_lft forever
inet6 fe80::ff:fe00:202/64 scope link
valid_lft forever preferred_lft forever
- 4: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master vrf-red state UP group default qlen 1000
+ 4: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master red state UP group default qlen 1000
link/ether 02:00:00:00:02:03 brd ff:ff:ff:ff:ff:ff
inet 10.2.2.2/24 brd 10.2.2.255 scope global eth2
valid_lft forever preferred_lft forever
valid_lft forever preferred_lft forever
inet6 fe80::ff:fe00:203/64 scope link
valid_lft forever preferred_lft forever
- 7: eth5: <BROADCAST,MULTICAST> mtu 1500 qdisc noop master vrf-red state DOWN group default qlen 1000
+ 7: eth5: <BROADCAST,MULTICAST> mtu 1500 qdisc noop master red state DOWN group default qlen 1000
link/ether 02:00:00:00:02:06 brd ff:ff:ff:ff:ff:ff
Or in brief format:
- $ ip -br addr show master vrf-red
+ $ ip -br addr show vrf red
eth1 UP 10.2.1.2/24 2002:1::2/120 fe80::ff:fe00:202/64
eth2 UP 10.2.2.2/24 2002:2::2/120 fe80::ff:fe00:203/64
eth5 DOWN
To show routes for a VRF use the ip command to display the table associated
with the VRF device:
+ $ ip [-6] route show vrf NAME
$ ip [-6] route show table ID
For example:
- $ ip route show table vrf-red
+ $ ip route show vrf red
prohibit default
broadcast 10.2.1.0 dev eth1 proto kernel scope link src 10.2.1.2
10.2.1.0/24 dev eth1 proto kernel scope link src 10.2.1.2
local 10.2.2.2 dev eth2 proto kernel scope host src 10.2.2.2
broadcast 10.2.2.255 dev eth2 proto kernel scope link src 10.2.2.2
- $ ip -6 route show table vrf-red
+ $ ip -6 route show vrf red
local 2002:1:: dev lo proto none metric 0 pref medium
local 2002:1::2 dev lo proto none metric 0 pref medium
2002:1::/120 dev eth1 proto kernel metric 256 pref medium
local fe80::ff:fe00:203 dev lo proto none metric 0 pref medium
fe80::/64 dev eth1 proto kernel metric 256 pref medium
fe80::/64 dev eth2 proto kernel metric 256 pref medium
- ff00::/8 dev vrf-red metric 256 pref medium
+ ff00::/8 dev red metric 256 pref medium
ff00::/8 dev eth1 metric 256 pref medium
ff00::/8 dev eth2 metric 256 pref medium
8. Route Lookup for a VRF
- A test route lookup can be done for a VRF by adding the oif option to ip:
- $ ip [-6] route get oif VRF-NAME ADDRESS
+ A test route lookup can be done for a VRF:
+ $ ip [-6] route get vrf NAME ADDRESS
+ $ ip [-6] route get oif NAME ADDRESS
For example:
- $ ip route get 10.2.1.40 oif vrf-red
- 10.2.1.40 dev eth1 table vrf-red src 10.2.1.2
+ $ ip route get 10.2.1.40 vrf red
+ 10.2.1.40 dev eth1 table red src 10.2.1.2
cache
- $ ip -6 route get 2002:1::32 oif vrf-red
- 2002:1::32 from :: dev eth1 table vrf-red proto kernel src 2002:1::2 metric 256 pref medium
+ $ ip -6 route get 2002:1::32 vrf red
+ 2002:1::32 from :: dev eth1 table red proto kernel src 2002:1::2 metric 256 pref medium
9. Removing Network Interface from a VRF
Commands used in this example:
-cat >> /etc/iproute2/rt_tables <<EOF
-1 vrf-mgmt
-10 vrf-red
-66 vrf-blue
-81 vrf-green
+cat >> /etc/iproute2/rt_tables.d/vrf.conf <<EOF
+1 mgmt
+10 red
+66 blue
+81 green
EOF
function vrf_create
{
VRF=$1
TBID=$2
- # create VRF device
- ip link add vrf-${VRF} type vrf table ${TBID}
- # add rules that direct lookups to vrf table
- ip ru add pref 200 oif vrf-${VRF} table ${TBID}
- ip ru add pref 200 iif vrf-${VRF} table ${TBID}
- ip -6 ru add pref 200 oif vrf-${VRF} table ${TBID}
- ip -6 ru add pref 200 iif vrf-${VRF} table ${TBID}
+ # create VRF device
+ ip link add ${VRF} type vrf table ${TBID}
if [ "${VRF}" != "mgmt" ]; then
- ip route add table ${TBID} prohibit default
+ ip route add table ${TBID} unreachable default
fi
- ip link set dev vrf-${VRF} up
- ip link set dev vrf-${VRF} state up
+ ip link set dev ${VRF} up
}
vrf_create mgmt 1
-ip link set dev eth0 master vrf-mgmt
+ip link set dev eth0 master mgmt
vrf_create red 10
-ip link set dev eth1 master vrf-red
-ip link set dev eth2 master vrf-red
-ip link set dev eth5 master vrf-red
+ip link set dev eth1 master red
+ip link set dev eth2 master red
+ip link set dev eth5 master red
vrf_create blue 66
-ip link set dev eth3 master vrf-blue
+ip link set dev eth3 master blue
vrf_create green 81
-ip link set dev eth4 master vrf-green
+ip link set dev eth4 master green
Interface addresses from /etc/network/interfaces:
projects / GitHub / LineageOS / android_kernel_motorola_exynos9610.git / commitdiff