1 [[sysadmin_network_configuration]]
8 Network configuration can be done either via the GUI, or by manually
9 editing the file `/etc/network/interfaces`, which contains the
10 whole network configuration. The `interfaces(5)` manual page contains the
11 complete format description. All {pve} tools try hard to keep direct
12 user modifications, but using the GUI is still preferable, because it
13 protects you from errors.
15 Once the network is configured, you can use the Debian traditional tools `ifup`
16 and `ifdown` commands to bring interfaces up and down.
21 {pve} does not write changes directly to `/etc/network/interfaces`. Instead, we
22 write into a temporary file called `/etc/network/interfaces.new`, this way you
23 can do many related changes at once. This also allows to ensure your changes
24 are correct before applying, as a wrong network configuration may render a node
30 With the default installed `ifupdown` network managing package you need to
31 reboot to commit any pending network changes. Most of the time, the basic {pve}
32 network setup is stable and does not change often, so rebooting should not be
35 Reload Network with ifupdown2
36 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
38 With the optional `ifupdown2` network managing package you also can reload the
39 network configuration live, without requiring a reboot.
41 NOTE: 'ifupdown2' cannot understand 'OpenVSwitch' syntax, so reloading is *not*
42 possible if OVS interfaces are configured.
44 Since {pve} 6.1 you can apply pending network changes over the web-interface,
45 using the 'Apply Configuration' button in the 'Network' panel of a node.
47 To install 'ifupdown2' ensure you have the latest {pve} updates installed, then
49 WARNING: installing 'ifupdown2' will remove 'ifupdown', but as the removal
50 scripts of 'ifupdown' before version '0.8.35+pve1' have a issue where network
51 is fully stopped on removal footnote:[Introduced with Debian Buster:
52 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=945877] you *must* ensure
53 that you have a up to date 'ifupdown' package version.
55 For the installation itself you can then simply do:
59 With that you're all set. You can also switch back to the 'ifupdown' variant at
60 any time, if you run into issues.
65 We currently use the following naming conventions for device names:
67 * Ethernet devices: en*, systemd network interface names. This naming scheme is
68 used for new {pve} installations since version 5.0.
70 * Ethernet devices: eth[N], where 0 ≤ N (`eth0`, `eth1`, ...) This naming
71 scheme is used for {pve} hosts which were installed before the 5.0
72 release. When upgrading to 5.0, the names are kept as-is.
74 * Bridge names: vmbr[N], where 0 ≤ N ≤ 4094 (`vmbr0` - `vmbr4094`)
76 * Bonds: bond[N], where 0 ≤ N (`bond0`, `bond1`, ...)
78 * VLANs: Simply add the VLAN number to the device name,
79 separated by a period (`eno1.50`, `bond1.30`)
81 This makes it easier to debug networks problems, because the device
82 name implies the device type.
84 Systemd Network Interface Names
85 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
87 Systemd uses the two character prefix 'en' for Ethernet network
88 devices. The next characters depends on the device driver and the fact
89 which schema matches first.
91 * o<index>[n<phys_port_name>|d<dev_port>] — devices on board
93 * s<slot>[f<function>][n<phys_port_name>|d<dev_port>] — device by hotplug id
95 * [P<domain>]p<bus>s<slot>[f<function>][n<phys_port_name>|d<dev_port>] — devices by bus id
97 * x<MAC> — device by MAC address
99 The most common patterns are:
101 * eno1 — is the first on board NIC
103 * enp3s0f1 — is the NIC on pcibus 3 slot 0 and use the NIC function 1.
105 For more information see https://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames/[Predictable Network Interface Names].
107 Choosing a network configuration
108 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
110 Depending on your current network organization and your resources you can
111 choose either a bridged, routed, or masquerading networking setup.
113 {pve} server in a private LAN, using an external gateway to reach the internet
114 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
116 The *Bridged* model makes the most sense in this case, and this is also
117 the default mode on new {pve} installations.
118 Each of your Guest system will have a virtual interface attached to the
119 {pve} bridge. This is similar in effect to having the Guest network card
120 directly connected to a new switch on your LAN, the {pve} host playing the role
123 {pve} server at hosting provider, with public IP ranges for Guests
124 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
126 For this setup, you can use either a *Bridged* or *Routed* model, depending on
127 what your provider allows.
129 {pve} server at hosting provider, with a single public IP address
130 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
132 In that case the only way to get outgoing network accesses for your guest
133 systems is to use *Masquerading*. For incoming network access to your guests,
134 you will need to configure *Port Forwarding*.
136 For further flexibility, you can configure
137 VLANs (IEEE 802.1q) and network bonding, also known as "link
138 aggregation". That way it is possible to build complex and flexible
141 Default Configuration using a Bridge
142 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
144 [thumbnail="default-network-setup-bridge.svg"]
145 Bridges are like physical network switches implemented in software.
146 All virtual guests can share a single bridge, or you can create multiple
147 bridges to separate network domains. Each host can have up to 4094 bridges.
149 The installation program creates a single bridge named `vmbr0`, which
150 is connected to the first Ethernet card. The corresponding
151 configuration in `/etc/network/interfaces` might look like this:
155 iface lo inet loopback
157 iface eno1 inet manual
160 iface vmbr0 inet static
162 netmask 255.255.255.0
169 Virtual machines behave as if they were directly connected to the
170 physical network. The network, in turn, sees each virtual machine as
171 having its own MAC, even though there is only one network cable
172 connecting all of these VMs to the network.
177 Most hosting providers do not support the above setup. For security
178 reasons, they disable networking as soon as they detect multiple MAC
179 addresses on a single interface.
181 TIP: Some providers allow you to register additional MACs through their
182 management interface. This avoids the problem, but can be clumsy to
183 configure because you need to register a MAC for each of your VMs.
185 You can avoid the problem by ``routing'' all traffic via a single
186 interface. This makes sure that all network packets use the same MAC
189 [thumbnail="default-network-setup-routed.svg"]
190 A common scenario is that you have a public IP (assume `198.51.100.5`
191 for this example), and an additional IP block for your VMs
192 (`203.0.113.16/29`). We recommend the following setup for such
197 iface lo inet loopback
200 iface eno1 inet static
202 netmask 255.255.255.0
204 post-up echo 1 > /proc/sys/net/ipv4/ip_forward
205 post-up echo 1 > /proc/sys/net/ipv4/conf/eno1/proxy_arp
209 iface vmbr0 inet static
211 netmask 255.255.255.248
218 Masquerading (NAT) with `iptables`
219 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
221 Masquerading allows guests having only a private IP address to access the
222 network by using the host IP address for outgoing traffic. Each outgoing
223 packet is rewritten by `iptables` to appear as originating from the host,
224 and responses are rewritten accordingly to be routed to the original sender.
228 iface lo inet loopback
232 iface eno1 inet static
234 netmask 255.255.255.0
239 iface vmbr0 inet static
241 netmask 255.255.255.0
246 post-up echo 1 > /proc/sys/net/ipv4/ip_forward
247 post-up iptables -t nat -A POSTROUTING -s '10.10.10.0/24' -o eno1 -j MASQUERADE
248 post-down iptables -t nat -D POSTROUTING -s '10.10.10.0/24' -o eno1 -j MASQUERADE
251 NOTE: In some masquerade setups with firewall enabled, conntrack zones might be
252 needed for outgoing connections. Otherwise the firewall could block outgoing
253 connections since they will prefer the `POSTROUTING` of the VM bridge (and not
256 Adding these lines in the `/etc/network/interfaces` can fix this problem:
259 post-up iptables -t raw -I PREROUTING -i fwbr+ -j CT --zone 1
260 post-down iptables -t raw -D PREROUTING -i fwbr+ -j CT --zone 1
263 For more information about this, refer to the following links:
265 https://commons.wikimedia.org/wiki/File:Netfilter-packet-flow.svg[Netfilter Packet Flow]
267 https://lwn.net/Articles/370152/[Patch on netdev-list introducing conntrack zones]
269 https://blog.lobraun.de/2019/05/19/prox/[Blog post with a good explanation by using TRACE in the raw table]
276 Bonding (also called NIC teaming or Link Aggregation) is a technique
277 for binding multiple NIC's to a single network device. It is possible
278 to achieve different goals, like make the network fault-tolerant,
279 increase the performance or both together.
281 High-speed hardware like Fibre Channel and the associated switching
282 hardware can be quite expensive. By doing link aggregation, two NICs
283 can appear as one logical interface, resulting in double speed. This
284 is a native Linux kernel feature that is supported by most
285 switches. If your nodes have multiple Ethernet ports, you can
286 distribute your points of failure by running network cables to
287 different switches and the bonded connection will failover to one
288 cable or the other in case of network trouble.
290 Aggregated links can improve live-migration delays and improve the
291 speed of replication of data between Proxmox VE Cluster nodes.
293 There are 7 modes for bonding:
295 * *Round-robin (balance-rr):* Transmit network packets in sequential
296 order from the first available network interface (NIC) slave through
297 the last. This mode provides load balancing and fault tolerance.
299 * *Active-backup (active-backup):* Only one NIC slave in the bond is
300 active. A different slave becomes active if, and only if, the active
301 slave fails. The single logical bonded interface's MAC address is
302 externally visible on only one NIC (port) to avoid distortion in the
303 network switch. This mode provides fault tolerance.
305 * *XOR (balance-xor):* Transmit network packets based on [(source MAC
306 address XOR'd with destination MAC address) modulo NIC slave
307 count]. This selects the same NIC slave for each destination MAC
308 address. This mode provides load balancing and fault tolerance.
310 * *Broadcast (broadcast):* Transmit network packets on all slave
311 network interfaces. This mode provides fault tolerance.
313 * *IEEE 802.3ad Dynamic link aggregation (802.3ad)(LACP):* Creates
314 aggregation groups that share the same speed and duplex
315 settings. Utilizes all slave network interfaces in the active
316 aggregator group according to the 802.3ad specification.
318 * *Adaptive transmit load balancing (balance-tlb):* Linux bonding
319 driver mode that does not require any special network-switch
320 support. The outgoing network packet traffic is distributed according
321 to the current load (computed relative to the speed) on each network
322 interface slave. Incoming traffic is received by one currently
323 designated slave network interface. If this receiving slave fails,
324 another slave takes over the MAC address of the failed receiving
327 * *Adaptive load balancing (balance-alb):* Includes balance-tlb plus receive
328 load balancing (rlb) for IPV4 traffic, and does not require any
329 special network switch support. The receive load balancing is achieved
330 by ARP negotiation. The bonding driver intercepts the ARP Replies sent
331 by the local system on their way out and overwrites the source
332 hardware address with the unique hardware address of one of the NIC
333 slaves in the single logical bonded interface such that different
334 network-peers use different MAC addresses for their network packet
337 If your switch support the LACP (IEEE 802.3ad) protocol then we recommend using
338 the corresponding bonding mode (802.3ad). Otherwise you should generally use the
339 active-backup mode. +
340 // http://lists.linux-ha.org/pipermail/linux-ha/2013-January/046295.html
341 If you intend to run your cluster network on the bonding interfaces, then you
342 have to use active-passive mode on the bonding interfaces, other modes are
345 The following bond configuration can be used as distributed/shared
346 storage network. The benefit would be that you get more speed and the
347 network will be fault-tolerant.
349 .Example: Use bond with fixed IP address
352 iface lo inet loopback
354 iface eno1 inet manual
356 iface eno2 inet manual
358 iface eno3 inet manual
361 iface bond0 inet static
362 bond-slaves eno1 eno2
364 netmask 255.255.255.0
367 bond-xmit-hash-policy layer2+3
370 iface vmbr0 inet static
372 netmask 255.255.255.0
381 [thumbnail="default-network-setup-bond.svg"]
382 Another possibility it to use the bond directly as bridge port.
383 This can be used to make the guest network fault-tolerant.
385 .Example: Use a bond as bridge port
388 iface lo inet loopback
390 iface eno1 inet manual
392 iface eno2 inet manual
395 iface bond0 inet manual
396 bond-slaves eno1 eno2
399 bond-xmit-hash-policy layer2+3
402 iface vmbr0 inet static
404 netmask 255.255.255.0
416 A virtual LAN (VLAN) is a broadcast domain that is partitioned and
417 isolated in the network at layer two. So it is possible to have
418 multiple networks (4096) in a physical network, each independent of
421 Each VLAN network is identified by a number often called 'tag'.
422 Network packages are then 'tagged' to identify which virtual network
426 VLAN for Guest Networks
427 ^^^^^^^^^^^^^^^^^^^^^^^
429 {pve} supports this setup out of the box. You can specify the VLAN tag
430 when you create a VM. The VLAN tag is part of the guest network
431 configuration. The networking layer supports different modes to
432 implement VLANs, depending on the bridge configuration:
434 * *VLAN awareness on the Linux bridge:*
435 In this case, each guest's virtual network card is assigned to a VLAN tag,
436 which is transparently supported by the Linux bridge.
437 Trunk mode is also possible, but that makes configuration
438 in the guest necessary.
440 * *"traditional" VLAN on the Linux bridge:*
441 In contrast to the VLAN awareness method, this method is not transparent
442 and creates a VLAN device with associated bridge for each VLAN.
443 That is, creating a guest on VLAN 5 for example, would create two
444 interfaces eno1.5 and vmbr0v5, which would remain until a reboot occurs.
446 * *Open vSwitch VLAN:*
447 This mode uses the OVS VLAN feature.
449 * *Guest configured VLAN:*
450 VLANs are assigned inside the guest. In this case, the setup is
451 completely done inside the guest and can not be influenced from the
452 outside. The benefit is that you can use more than one VLAN on a
459 To allow host communication with an isolated network. It is possible
460 to apply VLAN tags to any network device (NIC, Bond, Bridge). In
461 general, you should configure the VLAN on the interface with the least
462 abstraction layers between itself and the physical NIC.
464 For example, in a default configuration where you want to place
465 the host management address on a separate VLAN.
468 .Example: Use VLAN 5 for the {pve} management IP with traditional Linux bridge
471 iface lo inet loopback
473 iface eno1 inet manual
475 iface eno1.5 inet manual
478 iface vmbr0v5 inet static
480 netmask 255.255.255.0
487 iface vmbr0 inet manual
494 .Example: Use VLAN 5 for the {pve} management IP with VLAN aware Linux bridge
497 iface lo inet loopback
499 iface eno1 inet manual
503 iface vmbr0.5 inet static
505 netmask 255.255.255.0
509 iface vmbr0 inet manual
513 bridge-vlan-aware yes
516 The next example is the same setup but a bond is used to
517 make this network fail-safe.
519 .Example: Use VLAN 5 with bond0 for the {pve} management IP with traditional Linux bridge
522 iface lo inet loopback
524 iface eno1 inet manual
526 iface eno2 inet manual
529 iface bond0 inet manual
530 bond-slaves eno1 eno2
533 bond-xmit-hash-policy layer2+3
535 iface bond0.5 inet manual
538 iface vmbr0v5 inet static
540 netmask 255.255.255.0
547 iface vmbr0 inet manual
555 TODO: explain IPv6 support?