Exposing guest ports on the host

The --ports argument publishes a guest port on the host interface or all interfaces.

The following formats are supported:

  • interface:host-port:dest-port:/protocol
  • interface:host-port:dest-port
  • host-port:dest-port:/protocol
  • interface:dest-port
  • host-port:dest-port
  • dest-port:/protocol
  • dest-port

There are following rules to the parsing:

  • interface cannot be longer than 15 characters
  • if there is no host-port, the value is copied from the dest-port
  • port numbers must be higher than 9, the parser looks for minimum 2 digits
  • if no protocol is specified, /tcp is assumed

The parser parses the port values as integers but it validates that they are in the range of [1, 65535]. The initial parsing will match any three letter sequence at the protocol location but this is further validated to contain /tcp or /udp only; this check is case sensitive.

The integration is done via iptables. More details here.


  1. expose guest tcp port 16686 on host port 26686 on interface eno1: --port=eno1:26686:16686:/tcp
  2. expose guest udp port 6831 on host port 6831 on all interfaces: --port=6831:/tcp
  3. expose guest udp port 6831 on host port 16831 on all interfaces: --port=16831:6831:/tcp

Metadata location

The ports are stored in the VM metadata at .Configs.RunConfig.Ports path.


The ports are cleaned up when executing kill and purge commands for daemonized VMs and immediately on stop for non-daemonized VMs.