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Understanding VM Networking

Understanding Anka VM networking

Prerequisites

  1. You’ve installed the Anka Virtualization package
  2. You’ve created your first VM Template
  3. You grasp how to modify VM settings (like network)

We use Apple’s VMNET interface with “Using DHCP” for networking.

By default Anka VMs use a shared networking configuration with the host. It’s a kind of NAT + DHCP.

❯ anka --machine-readable describe 12.0-beta | jq '.body.network_cards'
[
  {
    "mode": "shared",
    "controller": "virtio-net"
  }
]

Every time you start/resume a VM it will be assigned an IP:

❯ anka show 12.0-beta
+---------+--------------------------------------+
| uuid    | 26c18e20-f67a-4387-a7b7-236a277bb424 |
+---------+--------------------------------------+
| name    | 12.0-beta (v2)                       |
+---------+--------------------------------------+
| created | Oct 18 13:57:57 2021                 |
+---------+--------------------------------------+
| vcpu    | 8                                    |
+---------+--------------------------------------+
| memory  | 12G                                  |
+---------+--------------------------------------+
| display | 1024x768                             |
+---------+--------------------------------------+
| disk    | 128GiB (22.84GiB on disk)            |
+---------+--------------------------------------+
| addons  | 3.0.0.135.8400565                    |
+---------+--------------------------------------+
| network | shared 192.168.64.6                  |
+---------+--------------------------------------+
| status  | running since Oct 25 15:48:36 2021   |
+---------+--------------------------------------+

❯ anka show 12.0-beta network
+------------+-------------------+
| mode       | shared            |
+------------+-------------------+
| controller | virtio-net        |
+------------+-------------------+
| ip         | 192.168.64.6      |
+------------+-------------------+
| mac        | ce:6b:90:1b:87:da |
+------------+-------------------+

If anka show does not display an IP, networking has either:

  1. Not fully started (give it a few more seconds).
  2. Networking cannot start due to some sort of host firewall or policy.
Within the VM, you can find an IP assigned to the host which can be used to ssh or transfer files out. To determine which IP is assigned to the host, execute ipconfig getoption en0 server_identifier (typically 192.168.64.1 for shared network mode and 192.168.128.1 for host network mode).

Changing the network configuration for Anka VMs

> anka modify 12.0.1-jenkins network --help
usage: network [options]

   Modify network card settings

options:
  -t,--mode <val>          network mode: shared/host/bridge/disconnected
  -b,--bridge <val>        host interface name to bridge with in the bridge mode, or "auto"
  -m,--mac <val>           specify fixed MAC address, or "auto"
  --direct-mac             expose --mac externally
  --no-direct-mac          do not expose --mac externally (default)
  -v,--vlan <val>          assign VLAN ID, 0 to deassign
  -c,--controller <val>    set controller: anet, virtio-net
  --local                  enable (default) inter-VM and VM-host communication
  --no-local               disable inter-VM and VM-host communication

❯ anka --machine-readable describe 12.0-beta | jq '.body.network_cards'
[
  {
    "mode": "shared",
    "controller": "virtio-net"
  }
]

❯ anka modify 12.0-beta network --mode bridge

❯ anka --machine-readable describe 12.0-beta | jq '.body.network_cards'
[
  {
    "mode": "bridge",
    "controller": "virtio-net"
  }
]
Type Description
shared The default network type operating as NAT + DHCP. Every VM after the start/resume gets an IP address assigned by the internal DHCP server in range 192.168.64.2 - 192.168.64.254. Programs inside a VM can access external networks (outside the host) and the internet directly. Also, other VMs on the host are also accessible.
host
Not currently supported.
bridge The Bridged type will cause the VM to show in the network as an individual device and receive a unique IP separate from the host.
An ENV is available to set the interface name: ANKA_BRIDGE_NAME=en0
When using the bridge, port-forwarding is not necessary as the VM will receive a unique IP that will be accessible directly to all other devices on the network.
By default, DHCP will not see your VM’s MAC address. You’ll need to enable --direct-mac for the network-card: anka modify VmName set network-card 0 --type bridged --direct-mac
You cannot use bridged networking over Wifi.
disconnected The VM will have a disconnected network cable.

MAC Addresses

Anka will dynamically assign MAC addresses to your VM. You can assign custom MAC Addresses with the anka modify network --mac option.

Be aware that if you clone your VM Template with a specific MAC, both VMs cannot run at the same time
Dynamic MAC Addresses are not guaranteed to be unique, though, reuse/collision is rare

FAQs

  • Should your Firewall software be blocking VM networking, you need to whitelist the ankanetd process.

What’s next?