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:
264 https://commons.wikimedia.org/wiki/File:Netfilter-packet-flow.svg[Netfilter Packet Flow]
265 https://lwn.net/Articles/370152/[Patch on netdev-list introducing conntrack zones]
266 https://blog.lobraun.de/2019/05/19/prox/[Blog post with a good explanation by using TRACE in the raw table]
273 Bonding (also called NIC teaming or Link Aggregation) is a technique
274 for binding multiple NIC's to a single network device. It is possible
275 to achieve different goals, like make the network fault-tolerant,
276 increase the performance or both together.
278 High-speed hardware like Fibre Channel and the associated switching
279 hardware can be quite expensive. By doing link aggregation, two NICs
280 can appear as one logical interface, resulting in double speed. This
281 is a native Linux kernel feature that is supported by most
282 switches. If your nodes have multiple Ethernet ports, you can
283 distribute your points of failure by running network cables to
284 different switches and the bonded connection will failover to one
285 cable or the other in case of network trouble.
287 Aggregated links can improve live-migration delays and improve the
288 speed of replication of data between Proxmox VE Cluster nodes.
290 There are 7 modes for bonding:
292 * *Round-robin (balance-rr):* Transmit network packets in sequential
293 order from the first available network interface (NIC) slave through
294 the last. This mode provides load balancing and fault tolerance.
296 * *Active-backup (active-backup):* Only one NIC slave in the bond is
297 active. A different slave becomes active if, and only if, the active
298 slave fails. The single logical bonded interface's MAC address is
299 externally visible on only one NIC (port) to avoid distortion in the
300 network switch. This mode provides fault tolerance.
302 * *XOR (balance-xor):* Transmit network packets based on [(source MAC
303 address XOR'd with destination MAC address) modulo NIC slave
304 count]. This selects the same NIC slave for each destination MAC
305 address. This mode provides load balancing and fault tolerance.
307 * *Broadcast (broadcast):* Transmit network packets on all slave
308 network interfaces. This mode provides fault tolerance.
310 * *IEEE 802.3ad Dynamic link aggregation (802.3ad)(LACP):* Creates
311 aggregation groups that share the same speed and duplex
312 settings. Utilizes all slave network interfaces in the active
313 aggregator group according to the 802.3ad specification.
315 * *Adaptive transmit load balancing (balance-tlb):* Linux bonding
316 driver mode that does not require any special network-switch
317 support. The outgoing network packet traffic is distributed according
318 to the current load (computed relative to the speed) on each network
319 interface slave. Incoming traffic is received by one currently
320 designated slave network interface. If this receiving slave fails,
321 another slave takes over the MAC address of the failed receiving
324 * *Adaptive load balancing (balance-alb):* Includes balance-tlb plus receive
325 load balancing (rlb) for IPV4 traffic, and does not require any
326 special network switch support. The receive load balancing is achieved
327 by ARP negotiation. The bonding driver intercepts the ARP Replies sent
328 by the local system on their way out and overwrites the source
329 hardware address with the unique hardware address of one of the NIC
330 slaves in the single logical bonded interface such that different
331 network-peers use different MAC addresses for their network packet
334 If your switch support the LACP (IEEE 802.3ad) protocol then we recommend using
335 the corresponding bonding mode (802.3ad). Otherwise you should generally use the
336 active-backup mode. +
337 // http://lists.linux-ha.org/pipermail/linux-ha/2013-January/046295.html
338 If you intend to run your cluster network on the bonding interfaces, then you
339 have to use active-passive mode on the bonding interfaces, other modes are
342 The following bond configuration can be used as distributed/shared
343 storage network. The benefit would be that you get more speed and the
344 network will be fault-tolerant.
346 .Example: Use bond with fixed IP address
349 iface lo inet loopback
351 iface eno1 inet manual
353 iface eno2 inet manual
356 iface bond0 inet static
359 netmask 255.255.255.0
362 bond_xmit_hash_policy layer2+3
365 iface vmbr0 inet static
367 netmask 255.255.255.0
376 [thumbnail="default-network-setup-bond.svg"]
377 Another possibility it to use the bond directly as bridge port.
378 This can be used to make the guest network fault-tolerant.
380 .Example: Use a bond as bridge port
383 iface lo inet loopback
385 iface eno1 inet manual
387 iface eno2 inet manual
390 iface bond0 inet manual
394 bond_xmit_hash_policy layer2+3
397 iface vmbr0 inet static
399 netmask 255.255.255.0
411 A virtual LAN (VLAN) is a broadcast domain that is partitioned and
412 isolated in the network at layer two. So it is possible to have
413 multiple networks (4096) in a physical network, each independent of
416 Each VLAN network is identified by a number often called 'tag'.
417 Network packages are then 'tagged' to identify which virtual network
421 VLAN for Guest Networks
422 ^^^^^^^^^^^^^^^^^^^^^^^
424 {pve} supports this setup out of the box. You can specify the VLAN tag
425 when you create a VM. The VLAN tag is part of the guest network
426 configuration. The networking layer supports different modes to
427 implement VLANs, depending on the bridge configuration:
429 * *VLAN awareness on the Linux bridge:*
430 In this case, each guest's virtual network card is assigned to a VLAN tag,
431 which is transparently supported by the Linux bridge.
432 Trunk mode is also possible, but that makes configuration
433 in the guest necessary.
435 * *"traditional" VLAN on the Linux bridge:*
436 In contrast to the VLAN awareness method, this method is not transparent
437 and creates a VLAN device with associated bridge for each VLAN.
438 That is, creating a guest on VLAN 5 for example, would create two
439 interfaces eno1.5 and vmbr0v5, which would remain until a reboot occurs.
441 * *Open vSwitch VLAN:*
442 This mode uses the OVS VLAN feature.
444 * *Guest configured VLAN:*
445 VLANs are assigned inside the guest. In this case, the setup is
446 completely done inside the guest and can not be influenced from the
447 outside. The benefit is that you can use more than one VLAN on a
454 To allow host communication with an isolated network. It is possible
455 to apply VLAN tags to any network device (NIC, Bond, Bridge). In
456 general, you should configure the VLAN on the interface with the least
457 abstraction layers between itself and the physical NIC.
459 For example, in a default configuration where you want to place
460 the host management address on a separate VLAN.
463 .Example: Use VLAN 5 for the {pve} management IP with traditional Linux bridge
466 iface lo inet loopback
468 iface eno1 inet manual
470 iface eno1.5 inet manual
473 iface vmbr0v5 inet static
475 netmask 255.255.255.0
482 iface vmbr0 inet manual
489 .Example: Use VLAN 5 for the {pve} management IP with VLAN aware Linux bridge
492 iface lo inet loopback
494 iface eno1 inet manual
498 iface vmbr0.5 inet static
500 netmask 255.255.255.0
504 iface vmbr0 inet manual
508 bridge_vlan_aware yes
511 The next example is the same setup but a bond is used to
512 make this network fail-safe.
514 .Example: Use VLAN 5 with bond0 for the {pve} management IP with traditional Linux bridge
517 iface lo inet loopback
519 iface eno1 inet manual
521 iface eno2 inet manual
524 iface bond0 inet manual
528 bond_xmit_hash_policy layer2+3
530 iface bond0.5 inet manual
533 iface vmbr0v5 inet static
535 netmask 255.255.255.0
542 iface vmbr0 inet manual
550 TODO: explain IPv6 support?