UDP port forwarding not working, always falls back to TCP

[kivoli]

Vagrant version

~ % vagrant -v
Vagrant 2.0.0

Host operating system

Debian Stretch

Guest operating system

Debian Stretch — doesn’t really matter

Vagrantfile

# -*- mode: ruby -*-
# vi: set ft=ruby :
# vim: ft=ruby:sw=2:ts=2:ss=2:expandtab

Vagrant.configure("2") do |config|
  config.vm.synced_folder ".", "/vagrant", disabled: true
  config.vm.box = "debian/stretch64"
  config.vm.network 'forwarded_port', host: 6666, guest: 6666, protocol: 'udp'
end

Debug output

https://gist.github.com/kivoli/fae9019c8612e9e50e9f697da94e2983
Note: Remove VAGRANT_OLD_* and identifying information from output.

Expected behavior

Port 6666 should be forwarded for protocol UDP.

Actual behavior

Port 666 is forwarded for protocol TCP.

% netstat -lnp | grep 666
tcp        0      0 127.0.0.1:6666          0.0.0.0:*               LISTEN      12186/ssh           
tcp6       0      0 ::1:6666                :::*                    LISTEN      12186/ssh  

Steps to reproduce

1. Create new Vagrant environment

cd $(mktemp -d) && cat >Vagrantfile <<EOF
# -*- mode: ruby -*-
# vi: set ft=ruby :
# vim: ft=ruby:sw=2:ts=2:ss=2:expandtab

Vagrant.configure("2") do |config|
  config.vm.synced_folder ".", "/vagrant", disabled: true
  config.vm.box = "debian/stretch64"
  config.vm.network 'forwarded_port', host: 6666, guest: 6666, protocol: 'udp'
end
EOF

2. Run vagrant up
3. Check port forwardings netstat -lnp | grep 6666

References

Example from the documentation doesn’t work either.

[kivoli]

A colleague pointed out that this may be up to the provider (libvirt) - checking this now; I though Vagrant is always using SSH to forward ports and that it is provider independent.

[kivoli]

Working with VirtualBox provider, seems to be a libvirt issue. Opened vagrant-libvirt#812.

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

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