VirtualBox

Opened 8 years ago

Last modified 7 years ago

#15303 reopened defect

NAT host adapter responds to traffic when it shouldn't — at Version 1

Reported by: Mike446 Owned by:
Component: network/NAT Version:
Keywords: Cc: virtualbox@…
Guest type: all Host type: other

Description (last modified by Valery Ushakov)

When using a NAT network, the host adapter will generate TCP RST packets in response to packets that are not destined for that interface. For example, here we have the following network setup:

52:54:00:12:35:02 10.0.2.2   VirtualBox router
08:00:27:7c:00:6c 10.0.2.15  VM

And the VM sends this packet:

TCP SYN
Src: Eth 08:00:27:7c:00:6c / IP 10.0.2.15  / TCP 15717
Dst: Eth 08:00:27:7c:00:6d / IP 10.0.2.100 / TCP 80

Then, the VM will receive this spurious packet:

TCP RST,ACK
Src: Eth 52:54:00:12:35:02 / IP 10.0.2.100 / TCP 80
Dst: Eth 08:00:27:7c:00:6c / IP 10.0.2.15  / TCP 15717

Note the soruce MAC. This is the host adapter's MAC. The expected result is that no packet will be sent in response to the original packet above, since the target host does not exist on the network and any other host receiving the packet should disregard it since the destination MAC does not match their MAC.

I have attached a pcap of the problem that was generated like this (nping is part of nmap):

arping -I enp0s3 -c 1 10.0.2.2
nping --tcp --dest-mac 08:00:27:7c:00:6d 10.0.2.100

Tested with VirtualBox 4.3.36, 5.0.12 and 5.0.16 using Debian, Ubuntu and FreeBSD.

Change History (2)

by Mike446, 8 years ago

Attachment: vbox-tcp-rst.pcap added

comment:1 by Valery Ushakov, 8 years ago

Description: modified (diff)
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