Problems with Synced Folders (Vagrant 1.2.2)

[dcunited001]

I'm having some problems setting up a sync'd folder on Vagrant, using the Ubuntu 12.04, CentOS 63 & CentOS 64 puppet images.

Vagrant is trying to run this command from ./plugins/hosts/linux/host.rb:91

system(%Q[sudo su root -c "echo '#{line}' >> /etc/exports"])

Vagrant keeps asking for a sudo password, even though there is no sudo password configured. While this is going on, I can vagrant ssh into the box and su root all day with no password, but Vagrant doesn't accept a blank password.

[server] Matching MAC address for NAT networking...
[server] Setting the name of the VM...
[server] Clearing any previously set forwarded ports...
[server] Creating shared folders metadata...
[server] Clearing any previously set network interfaces...
[server] Preparing network interfaces based on configuration...
[server] Forwarding ports...
[server] -- 22 => 2222 (adapter 1)
[server] Running any VM customizations...
[server] Booting VM...
[server] Waiting for VM to boot. This can take a few minutes.
[server] VM booted and ready for use!
[server] Setting hostname...
[server] Configuring and enabling network interfaces...
[server] Mounting shared folders...
[server] -- /vagrant
[server] Exporting NFS shared folders...
Preparing to edit /etc/exports. Administrator privileges will be required...
Password:
Sorry, try again.
Password:
Sorry, try again.
Password:
Sorry, try again.
sudo: 3 incorrect password attempts
Password:
Sorry, try again.
Password:
Sorry, try again.
Password:
Sorry, try again.
sudo: 3 incorrect password attempts
Password:
Sorry, try again.
Password:
Sorry, try again.
Password:
sudo: 2 incorrect password attempts
Password:
Sorry, try again.
Password:
Sorry, try again.
Password:
Sorry, try again.
sudo: 3 incorrect password attempts
[server] Mounting NFS shared folders...

The following SSH command responded with a non-zero exit status.
Vagrant assumes that this means the command failed!

mount -o vers=3 10.10.2.1:'/Users/myuser/dev' /opt/vagrant

[dcunited001]

Also, I'm using private_networking, but i don't think this is the issue.