Forwarded ports allow you to access a port on your host machine and have all data forwarded to a port on the guest machine, over either TCP or UDP.
For example: If the guest machine is running a web server listening on port 80,
you can make a forwarded port mapping to port 8080 (or anything) on your host
machine. You can then open your browser to
localhost:8080 and browse the
website, while all actual network data is being sent to the guest.
Defining a Forwarded Port
The forwarded port configuration expects two parameters, the port on the guest and the port on the host. Example:
Vagrant.configure("2") do |config| config.vm.network "forwarded_port", guest: 80, host: 8080 end
This will allow accessing port 80 on the guest via port 8080 on the host.
This is a complete list of the options that are available for forwarded
ports. Only the
host options are required. Below this section,
there are more detailed examples of using these options.
guest(int) - The port on the guest that you want to be exposed on the host. This can be any port.
guest_ip(string) - The guest IP to bind the forwarded port to. If this is not set, the port will go to the every interface. By default, this is empty.
host(int) - The port on the host that you want to use to access the port on the guest. This must be greater than port 1024 unless Vagrant is running as root (which is not recommended).
host_ip(string) - The IP on the host you want to bind the forwarded port to. If not specified, it will be bound to every IP. By default, this is empty.
protocol(string) - Either "udp" or "tcp". This specifies the protocol that will be allowed through the forwarded port. By default this is "tcp".
Forwarded Port Protocols
By default, any defined port will only forward the TCP protocol. As an optional
third parameter, you may specify
protocol: 'udp' in order to pass UDP
traffic. If a given port needs to be able to listen to the same port on both
protocols, you must define the port twice with each protocol specified, like
Vagrant.configure("2") do |config| config.vm.network "forwarded_port", guest: 2003, host: 12003, protocol: 'tcp' config.vm.network "forwarded_port", guest: 2003, host: 12003, protocol: 'udp' end
Port Collisions and Correction
It is common when running multiple Vagrant machines to unknowingly create forwarded port definitions that collide with each other (two separate Vagrant projects forwarded to port 8080, for example). Vagrant includes built-in mechanism to detect this and correct it, automatically.
Port collision detection is always done. Vagrant will not allow you to define a forwarded port where the port on the host appears to be accepting traffic or connections.
Port collision auto-correction must be manually enabled for each forwarded port, since it is often surprising when it occurs and can lead the Vagrant user to think that the port wasn't properly forwarded. Enabling auto correct is easy:
Vagrant.configure("2") do |config| config.vm.network "forwarded_port", guest: 80, host: 8080, auto_correct: true end
:auto_correct parameter set to true tells Vagrant to auto
correct any collisions. During a
vagrant up or
vagrant reload, Vagrant
will output information about any collisions detections and auto corrections
made, so you can take notice and act accordingly.