Type: proxy
¶
Note
The proxy
device type is supported for both containers (NAT and non-NAT modes) and VMs (NAT mode only).
It supports hotplugging for both containers and VMs.
Proxy devices allow forwarding network connections between host and instance. This method makes it possible to forward traffic hitting one of the host’s addresses to an address inside the instance, or to do the reverse and have an address in the instance connect through the host.
In NAT mode, a proxy device can be used for TCP and UDP proxying. In non-NAT mode, you can also proxy traffic between Unix sockets (which can be useful to, for example, forward graphical GUI or audio traffic from the container to the host system) or even across protocols (for example, you can have a TCP listener on the host system and forward its traffic to a Unix socket inside a container).
The supported connection types are:
tcp <-> tcp
udp <-> udp
unix <-> unix
tcp <-> unix
unix <-> tcp
udp <-> tcp
tcp <-> udp
udp <-> unix
unix <-> udp
To add a proxy
device, use the following command:
lxc config device add <instance_name> <device_name> proxy listen=<type>:<addr>:<port>[-<port>][,<port>] connect=<type>:<addr>:<port> bind=<host/instance_name>
Tip
Using a proxy device in NAT mode is very similar to adding a network forward.
The difference is that network forwards are applied on a network level, while a proxy device is added for an instance. In addition, network forwards cannot be used to proxy traffic between different connection types.
NAT mode¶
The proxy device also supports a NAT mode (nat=true
), where packets are forwarded using NAT rather than being proxied through a separate connection.
This mode has the benefit that the client address is maintained without the need for the target destination to support the HAProxy PROXY protocol (which is the only way to pass the client address through when using the proxy device in non-NAT mode).
However, NAT mode is supported only if the host that the instance is running on is the gateway (which is the case if you’re using lxdbr0
, for example).
In NAT mode, the supported connection types are:
tcp <-> tcp
udp <-> udp
When configuring a proxy device with nat=true
, you must ensure that the target instance has a static IP configured on its NIC device.
Specifying IP addresses¶
Use the following command to configure a static IP for an instance NIC:
lxc config device set <instance_name> <nic_name> ipv4.address=<ipv4_address> ipv6.address=<ipv6_address>
To define a static IPv6 address, the parent managed network must have ipv6.dhcp.stateful
enabled.
When defining IPv6 addresses, use the square bracket notation, for example:
connect=tcp:[2001:db8::1]:80
You can specify that the connect address should be the IP of the instance by setting the connect IP to the wildcard address (0.0.0.0
for IPv4 and [::]
for IPv6).
Note
The listen address can also use wildcard addresses when using non-NAT mode. However, when using NAT mode, you must specify an IP address on the LXD host.
Device options¶
proxy
devices have the following device options:
Key: | bind |
Type: | string |
Default: |
|
Required: | no |
Possible values are host
and instance
.
Key: | connect |
Type: | string |
Required: | yes |
Use the following format to specify the address and port: <type>:<addr>:<port>[-<port>][,<port>]
Key: | listen |
Type: | string |
Required: | yes |
Use the following format to specify the address and port: <type>:<addr>:<port>[-<port>][,<port>]
Key: | nat |
Type: | bool |
Default: |
|
Required: | no |
This option requires that the instance NIC has a static IP address.
Key: | proxy_protocol |
Type: | bool |
Default: |
|
Required: | no |
This option specifies whether to use the HAProxy PROXY protocol to transmit sender information.
Configuration examples¶
Add a proxy
device that forwards traffic from one address (the listen
address) to another address (the connect
address) using NAT mode:
lxc config device add <instance_name> <device_name> proxy nat=true listen=tcp:<ip_address>:<port> connect=tcp:<ip_address>:<port>
Add a proxy
device that forwards traffic going to a specific IP to a Unix socket on an instance that might not have a network connection:
lxc config device add <instance_name> <device_name> proxy listen=tcp:<ip_address>:<port> connect=unix:/<socket_path_on_instance>
Add a proxy
device that forwards traffic going to a Unix socket on an instance that might not have a network connection to a specific IP address:
lxc config device add <instance_name> <device_name> proxy bind=instance listen=unix:/<socket_path_on_instance> connect=tcp:<ip_address>:<port>
See Configure devices for more information.