NAT drops packets bigger than 388 byte towards guest
|Reported by:||Lukas Tribus||Owned by:|
|Guest type:||all||Host type:||all|
NAT mode does not work for me, because all packets bigger than 388 byte (IP packet length; 368 byte IP payload or 360 byte ICMP payload) are dropped.
The test is as simple as:
ping google.com -s 360 ping google.com -s 361
or on Windows guests:
ping google.com -l 360 ping google.com -l 361
The former (360 byte ICMP payload) works, while the latter (361 byte ICMP payload) doesn't.
I can reliably reproduce this with both Linux and Windows guests (32 and 64bit), on different hardware. The host always runs Windows Vista or Windows 7, both 64 bit. I did not test different host OS'.
The traffic of the testcase has been captured:
- via the nictrace feature; it is clear that the answer packets do not reach the guests
- via Wireshark on the host; all answer packets are seen (frame >= 25)
I have no clue why others don't see this behavior; on all my VirtualBox installations I see exactly this issue, and they are different installations on different hardware with different software.
Bridging mode works perfectly fine on those installations.