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[pve-docs.git] / pve-network.adoc
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1Network Configuration
2---------------------
3include::attributes.txt[]
4
5{pve} uses a bridged networking model. Each host can have up to 4094
6bridges. Bridges are like physical network switches implemented in
7software. All VMs can share a single bridge, as if
8virtual network cables from each guest were all plugged into the same
9switch. But you can also create multiple bridges to separate network
10domains.
11
12For connecting VMs to the outside world, bridges are attached to
13physical network cards. For further flexibility, you can configure
14VLANs (IEEE 802.1q) and network bonding, also known as "link
15aggregation". That way it is possible to build complex and flexible
16virtual networks.
17
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18Debian traditionally uses the `ifup` and `ifdown` commands to
19configure the network. The file `/etc/network/interfaces` contains the
20whole network setup. Please refer to to manual page (`man interfaces`)
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21for a complete format description.
22
23NOTE: {pve} does not write changes directly to
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24`/etc/network/interfaces`. Instead, we write into a temporary file
25called `/etc/network/interfaces.new`, and commit those changes when
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26you reboot the node.
27
28It is worth mentioning that you can directly edit the configuration
29file. All {pve} tools tries hard to keep such direct user
30modifications. Using the GUI is still preferable, because it
31protect you from errors.
32
5eba0743 33
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34Naming Conventions
35~~~~~~~~~~~~~~~~~~
36
37We currently use the following naming conventions for device names:
38
39* Ethernet devices: eth[N], where 0 ≤ N (`eth0`, `eth1`, ...)
40
41* Bridge names: vmbr[N], where 0 ≤ N ≤ 4094 (`vmbr0` - `vmbr4094`)
42
43* Bonds: bond[N], where 0 ≤ N (`bond0`, `bond1`, ...)
44
45* VLANs: Simply add the VLAN number to the device name,
46 separated by a period (`eth0.50`, `bond1.30`)
47
48This makes it easier to debug networks problems, because the device
49names implies the device type.
50
51Default Configuration using a Bridge
52~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
53
54The installation program creates a single bridge named `vmbr0`, which
55is connected to the first ethernet card `eth0`. The corresponding
8c1189b6 56configuration in `/etc/network/interfaces` looks like this:
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57
58----
59auto lo
60iface lo inet loopback
61
62iface eth0 inet manual
63
64auto vmbr0
65iface vmbr0 inet static
66 address 192.168.10.2
67 netmask 255.255.255.0
68 gateway 192.168.10.1
69 bridge_ports eth0
70 bridge_stp off
71 bridge_fd 0
72----
73
74Virtual machines behave as if they were directly connected to the
75physical network. The network, in turn, sees each virtual machine as
76having its own MAC, even though there is only one network cable
77connecting all of these VMs to the network.
78
79
80Routed Configuration
81~~~~~~~~~~~~~~~~~~~~
82
83Most hosting providers do not support the above setup. For security
84reasons, they disable networking as soon as they detect multiple MAC
85addresses on a single interface.
86
87TIP: Some providers allows you to register additional MACs on there
88management interface. This avoids the problem, but is clumsy to
89configure because you need to register a MAC for each of your VMs.
90
8c1189b6 91You can avoid the problem by ``routing'' all traffic via a single
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92interface. This makes sure that all network packets use the same MAC
93address.
94
8c1189b6 95A common scenario is that you have a public IP (assume `192.168.10.2`
0bcd1f7f 96for this example), and an additional IP block for your VMs
8c1189b6 97(`10.10.10.1/255.255.255.0`). We recommend the following setup for such
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98situations:
99
100----
101auto lo
102iface lo inet loopback
103
104auto eth0
105iface eth0 inet static
106 address 192.168.10.2
107 netmask 255.255.255.0
108 gateway 192.168.10.1
109 post-up echo 1 > /proc/sys/net/ipv4/conf/eth0/proxy_arp
110
111
112auto vmbr0
113iface vmbr0 inet static
114 address 10.10.10.1
115 netmask 255.255.255.0
116 bridge_ports none
117 bridge_stp off
118 bridge_fd 0
119----
120
121
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122Masquerading (NAT) with `iptables`
123~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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124
125In some cases you may want to use private IPs behind your Proxmox
126host's true IP, and masquerade the traffic using NAT:
127
128----
129auto lo
130iface lo inet loopback
131
132auto eth0
133#real IP adress
134iface eth0 inet static
135 address 192.168.10.2
136 netmask 255.255.255.0
137 gateway 192.168.10.1
138
139auto vmbr0
140#private sub network
141iface vmbr0 inet static
142 address 10.10.10.1
143 netmask 255.255.255.0
144 bridge_ports none
145 bridge_stp off
146 bridge_fd 0
147
148 post-up echo 1 > /proc/sys/net/ipv4/ip_forward
149 post-up iptables -t nat -A POSTROUTING -s '10.10.10.0/24' -o eth0 -j MASQUERADE
150 post-down iptables -t nat -D POSTROUTING -s '10.10.10.0/24' -o eth0 -j MASQUERADE
151----
152
153////
154TODO: explain IPv6 support?
155TODO: explan OVS
156////