virtualbox.org

Hello,

I am having a very strange problem with lost headers on packets when trying to contact a guest VM.

I have bare metal running CentOS 7 and VirtualBox v.5.0.14. I then have a guest running Ubuntu 15.10 using bridged networking. It has happily picked up its IP address from our DHCP server. The guest is running SSH and Apache.

All firewalls are disabled on VirtualBox host, guest and all clients used in the tests below.

I can SSH out from the guest to any other Linux host on our network. I can also connect to Windows Samba services, served out by Windows hosts.
SSH and Apache work when accessing guest from VirtualBox host. Likewise, I can SSH to VBox host from guest
SSH and Apache work when accessing guest from an Ubuntu laptop
SSH and Apache work when accessing guest from CentOS 7 VM
SSH to the VBox host using PuTTY in Windows works fine

Everything is working as it should, right?

SSH from any Windows host using PuTTY results in a "Packet was garbled on decryption" error
Apache from any Windows host results in either unintelligible text output to the screen, or it attempts to download a file which contains the same unintelligible text, depending on the browser

Using Solaris to get the Apache web page or SSH gives us a little more insight. I'm guessing it's behaving the same as the Windows hosts, except we get more debugging output.
The end of that line of numbers is different every time, with a hexadecimal string. i.e. And when using wget to get the webpage...
Note the No headers, assuming HTTP/0.9

Additionally, it takes a good few seconds to download this 11Kb file.

Using wget on an Ubuntu host:
No problems, no message about missing headers, it is done in the blink of an eye, as you'd expect.

And now here are the first lines of the index.html file that was downloaded on the Solaris host:
Normal, unmolested HTML code follows this.

The index.html file downloaded on the Ubuntu host does NOT contain these first lines. It is just the HTML code.

I am assuming that the missing headers are what is causing the unintelligible text when accessing the web page from a Windows host - the browsers don't know what the file is and therefore don't know how to display it. I am also assuming that the same goes for the SSH failures - missing headers.

I think that just about captures all the variables in this web of confusion.

Does anyone know what the heck is going on?

I have figured it out. It was annoyingly simple.

It was the virtual network adapter type. This was configured as Intel Pro/1000 MT Desktop.

I have switched it to the Paravirtualization adapter and the issues have disappeared.

This is annoying as a) Paravirtualization has much higher performance and b) this is the standard for KVM and has been fully supported since Kernel 2.6. Why is this not the default when I've told VBox I'm installing a modern Linux guest?

I'm submitting this to Oracle as a bug.