NAT incorrectly works with guest's with static-assigned IP addresses -> fixed in SVNand uses ARP announce mechanism.

[Francis Moreau]

Hello,

I'm using VBOX 4.0.2, with a Linux guest which is using NAT.

The guest can do ping, ping www.virtualbox.org works, but doing wget www.virtualbox.org doesn't work, wget application is waiting for the HTTP server answer.

I'm attaching the pcap file which logs the vbox network activity.

I'm also attaching the host tcpdump log.

[Francis Moreau]

VBox.log

[Francis Moreau]

packet trace on the VM level when doing wget www.virtualbox.org

[Francis Moreau]

A tcpdump trace at the host level when doing wget www.virtualbox.org

[vasily Levchenko]

While conversation on IRC we've found that this guest uses static-assigned IP, which leads to broadcasting of all IP traffic, dropped by guest TCP/IP stack.

[vasily Levchenko]

And I was able to reproduce issue locally.

[vasily Levchenko]

Affected guests use ARP announce mechanism only.

[vasily Levchenko]

Some distros like Mandriva executes arping -U and arping -A in case of statically assigned IP in ethernet initialization scripts, that results that guest generates Gratuitous ARP packets, without respect to sysctl *.arp_notify.

[Francis Moreau]

Replying to Hachiman:

BTW, I'm wondering what was going on on the NAT side: does it incorreclty set an entry in the ARP table for the guest to broadcast ethernet address, or does it add no entry at all ?

Thanks

[vasily Levchenko]

It's used not right fields: in case ARP Gratuitous requests and response source IP and Ether are the same, but target pair is different in one case it's exactly copy of source ones, and in other target broadcast ethernet and source IP; that made collision in mandriva case. Now we use source pair and in case of any type of announce (arping or arp_notify) we print result to the log. Probably we should add some logging for statically address assigned guests without notification for information.