bbaf0bc9e4fabc24d0562be19e0cfe21882aa616
[pve-docs.git] / pve-network.adoc
1 Network Configuration
2 ---------------------
3 include::attributes.txt[]
4
5 {pve} uses a bridged networking model. Each host can have up to 4094
6 bridges. Bridges are like physical network switches implemented in
7 software. All VMs can share a single bridge, as if
8 virtual network cables from each guest were all plugged into the same
9 switch. But you can also create multiple bridges to separate network
10 domains.
11
12 For connecting VMs to the outside world, bridges are attached to
13 physical network cards. For further flexibility, you can configure
14 VLANs (IEEE 802.1q) and network bonding, also known as "link
15 aggregation". That way it is possible to build complex and flexible
16 virtual networks.
17
18 Debian traditionally uses the `ifup` and `ifdown` commands to
19 configure the network. The file `/etc/network/interfaces` contains the
20 whole network setup. Please refer to to manual page (`man interfaces`)
21 for a complete format description.
22
23 NOTE: {pve} does not write changes directly to
24 `/etc/network/interfaces`. Instead, we write into a temporary file
25 called `/etc/network/interfaces.new`, and commit those changes when
26 you reboot the node.
27
28 It is worth mentioning that you can directly edit the configuration
29 file. All {pve} tools tries hard to keep such direct user
30 modifications. Using the GUI is still preferable, because it
31 protect you from errors.
32
33
34 Naming Conventions
35 ~~~~~~~~~~~~~~~~~~
36
37 We 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
48 This makes it easier to debug networks problems, because the device
49 names implies the device type.
50
51 Default Configuration using a Bridge
52 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
53
54 The installation program creates a single bridge named `vmbr0`, which
55 is connected to the first ethernet card `eth0`. The corresponding
56 configuration in `/etc/network/interfaces` looks like this:
57
58 ----
59 auto lo
60 iface lo inet loopback
61
62 iface eth0 inet manual
63
64 auto vmbr0
65 iface 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
74 Virtual machines behave as if they were directly connected to the
75 physical network. The network, in turn, sees each virtual machine as
76 having its own MAC, even though there is only one network cable
77 connecting all of these VMs to the network.
78
79
80 Routed Configuration
81 ~~~~~~~~~~~~~~~~~~~~
82
83 Most hosting providers do not support the above setup. For security
84 reasons, they disable networking as soon as they detect multiple MAC
85 addresses on a single interface.
86
87 TIP: Some providers allows you to register additional MACs on there
88 management interface. This avoids the problem, but is clumsy to
89 configure because you need to register a MAC for each of your VMs.
90
91 You can avoid the problem by ``routing'' all traffic via a single
92 interface. This makes sure that all network packets use the same MAC
93 address.
94
95 A common scenario is that you have a public IP (assume `192.168.10.2`
96 for this example), and an additional IP block for your VMs
97 (`10.10.10.1/255.255.255.0`). We recommend the following setup for such
98 situations:
99
100 ----
101 auto lo
102 iface lo inet loopback
103
104 auto eth0
105 iface 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
112 auto vmbr0
113 iface 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
122 Masquerading (NAT) with `iptables`
123 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
124
125 In some cases you may want to use private IPs behind your Proxmox
126 host's true IP, and masquerade the traffic using NAT:
127
128 ----
129 auto lo
130 iface lo inet loopback
131
132 auto eth0
133 #real IP adress
134 iface eth0 inet static
135 address 192.168.10.2
136 netmask 255.255.255.0
137 gateway 192.168.10.1
138
139 auto vmbr0
140 #private sub network
141 iface 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 ////
154 TODO: explain IPv6 support?
155 TODO: explan OVS
156 ////