How can I troubleshoot VirtualBox port forwarding from Windows guest to Mac OS X host not working?

Super User Asked by jlarson on January 1, 2022

There is a plethora of questions about VirtualBox port forwarding problems but none with my specific details.
Details of setup:

I have a Windows 7 Professional 64bit install living in VirtualBox 4.1.2, hosted within Mac OS X 10.6.8. I’ve got several webservers running on localhost on different ports within the Windows install. I cannot for the life of me get port forwarding to work so I can access those webservers from Mac OS X.

My settings look like this; yes I have a NAT adapter:

enter image description here

And in my VirtualBox configuration file the relavent portion looks like this:

  <DNS pass-domain="true" use-proxy="false" use-host-resolver="false"/>
  <Alias logging="false" proxy-only="false" use-same-ports="false"/>
  <Forwarding name="RLPWeb" proto="1" hostport="7084" guestip="" guestport="7084"/>
  <Forwarding name="UtilWeb" proto="1" hostport="4040" guestip="" guestport="4040"/>
  <Forwarding name="WCARLP" proto="1" hostport="8084" guestip="" guestport="8084"/>
  <Forwarding name="WCAUtil" proto="1" hostport="4848" guestip="" guestport="4848"/>

I’ve turned off the Windows firewall to ensure it is not interfering, and I am not running a firewall on Mac OS X.

Anyway, when I attempt to go to for example on any of my Mac OS X browsers, it will eventually time out.

The log file for this VM shows that it is correctly reading the settings and implying it’s doing the right thing here:

00:00:08.286 NAT: set redirect TCP host port 4848 => guest port 4848 @
00:00:08.286 NAT: set redirect TCP host port 8084 => guest port 8084 @
00:00:08.286 NAT: set redirect TCP host port 4040 => guest port 4040 @
00:00:08.286 NAT: set redirect TCP host port 7084 => guest port 7084 @
00:00:08.290 Changing the VM state from 'LOADING' to 'SUSPENDED'.
00:00:08.290 Changing the VM state from 'SUSPENDED' to 'RESUMING'.
00:00:08.290 Changing the VM state from 'RESUMING' to 'RUNNING'.
00:00:08.337 Display::handleDisplayResize(): uScreenId = 0, pvVRAM=000000012017d000 w=1834 h=929 bpp=32 cbLine=0x1CA8, flags=0x1
00:00:09.139 AIOMgr: Host limits number of active IO requests to 16. Expect a performance impact.
00:00:13.454 NAT: DHCP offered IP address

I’ve tried setting the Host IP to, and I’ve tried setting Guest IP blank and also None of these seem to help.

What else can I look at to troubleshoot this issue?

3 Answers

According to the VirtualBox official documentation, the preferred way to do this is with your network mode set to Host-Only or Bridged.

tl;dr: Use Bridged, not NAT.


Answered by villasenor on January 1, 2022

Have you tried bridging the connection from the windows vm out to the Mac? Being under Network Address Translation NAT has proven to be a headache for me as well when inside a VM. Having a bridge provides the VM with an IP that the host can see. Given your port forwarding situation this shouldn't be an issue but I would try to forward ports from actual IPs rather than translated ones.

Answered by market_zero on January 1, 2022

I have noticed problems with port forwards on macOS X VirtualBox host.

Using network adapter PCnet-Fast III (Am79C973) and Oracle Developer Day image as guest.

When ever I suspend the guest and resume it all port forwards are lost.

I am not certain if the problems are related to the network adapter or to the guest but I fail to see how the guest could be aware of the port forwards.

This is a long shot, but if you have anything in common with this case, try shutting down (complete power off of the guest) and starting up with the port forwards set. Immediately test if any of the port forwards work and only after positive results try suspending and resuming the guest.

Answered by PeteS on January 1, 2022

Add your own answers!

Related Questions

Setting PWM Backlight brightness on boot

3  Asked on December 20, 2021 by antoinec


LibreSSL syscall error

1  Asked on December 20, 2021


Issue with Twitter and my router

0  Asked on December 18, 2021


Ask a Question

Get help from others!

© 2023 All rights reserved. Sites we Love: PCI Database, UKBizDB, Menu Kuliner, Sharing RPP