Ticket #8395 (closed defect: obsolete)
OSX host networking UDP odd behaviour when VirtualBox VM running
|Reported by:||DaveHill1805||Owned by:|
|Host type:||Mac OS X|
Description (last modified by Hachiman) (diff)
OSX host (10.5.8) connected to network via en0, IP address 192.168.5.2
Linux Guest (Centos 5.5 32bit) using bridged networking, IP address 192.168.5.3
Host also runs "bind" caching name server.
When guest is running, *some* DNS queries (either from the guest or from other machines in the network) fail with "timed out". When guest is not running, all is OK.
It doesn't matter if the guest is actually booted (I interrupted the boot at the GRUB screen), the problem is still there.
example from another OSX laptop on the network, querying the DNS server on the OSX VB host:
dhcp102:~ dave$ host mx1.cmail3.com 192.168.5.2 ;; connection timed out; no servers could be reached dhcp102:~ dave$
but if I query my other (old) DNS server then it works:
dhcp102:~ dave$ host mx1.cmail3.com 192.168.5.5 Using domain server: Name: 192.168.5.5 Address: 192.168.5.5#53 Aliases: mx1.cmail3.com has address 18.104.22.168 mx1.cmail3.com has address 22.214.171.124 dhcp102:~ dave$
and if I query for something else on either DNS server it works!
dhcp102:~ dave$ host mx2.cmail3.com 192.168.5.2 Using domain server: Name: 192.168.5.2 Address: 192.168.5.2#53 Aliases: mx2.cmail3.com has address 126.96.36.199 dhcp102:~ dave$ host mx2.cmail3.com 192.168.5.5 Using domain server: Name: 192.168.5.5 Address: 192.168.5.5#53 Aliases: mx2.cmail3.com has address 188.8.131.52 dhcp102:~ dave$
So it depends on the size of the packets.
Running a packet capture from both ends shows that it all *looks* OK, until you enable "calculate checksums" for UDP in Wireshark, then it shows that the UDP checksum is wrong on the packets that "go missing".
When the problem occurs, the following message is logged on the OSX host console log:
Feb 21 22:52:57 henry kernel: in_delayed_cksum_offset: ip_len 49408 (193) doesn't match actual length 207