OSX host networking UDP odd behaviour when VirtualBox VM running

[Dave Hill]

Setup:

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 206.72.127.155
mx1.cmail3.com has address 206.72.127.149
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 206.72.127.216
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 206.72.127.216
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[0]: in_delayed_cksum_offset: ip_len 49408 (193) doesn't match actual length 207

[Dave Hill]

tcpdump capture taken on the host

[wsourdeau]

Same kind of issue here when using a SIP client on OSX (Telephone.app, Blink.app). The problem shows up as soon as the virtual machine is launched, before the kernel is even loaded. The type of guest does not seem to matter.

[wsourdeau]

Replying to wsourdeau:

Same kind of issue here when using a SIP client on OSX (Telephone.app, Blink.app). The problem shows up as soon as the virtual machine is launched, before the kernel is even loaded. The type of guest does not seem to matter.

Meaning that, using SIP, I can hear people (inbound udp packets) but they can't hear me (outbound udp packets).

[Kooorrg]

This issue is still present in VB 4.1 running on Mac OS X 10.6.8. It prevents a computer running VB to serve as a DNS server and generates hard-to-track-down errors as UDP packets simply "disappear". See: ​https://discussions.apple.com/message/15824826

Messing up UDP packets that are even going to the VB guest is a big issue: could someone look into it ?

[AndrewSharpe]

Seeing this issue on VB 4.1.8 with OSX 10.5.8 host and debian lenny client. I am also running named on the host (this is where the problem first becomes apparent).

[AndrewSharpe]

Replying to AndrewSharpe:

Seeing this issue on VB 4.1.8 with OSX 10.5.8 host and debian lenny client. I am also running named on the host (this is where the problem first becomes apparent).

This problem appears to have disappeared after rolling back to 4.1.6

[AndrewSharpe]

Replying to AndrewSharpe:

Replying to AndrewSharpe:

Seeing this issue on VB 4.1.8 with OSX 10.5.8 host and debian lenny client. I am also running named on the host (this is where the problem first becomes apparent).

This problem appears to have disappeared after rolling back to 4.1.6

Retract the last post. The problem does still exist when using 4.1.6 and I can see it when attempting to resolve 'centos.mirror.aussiehq.net.au'.

[vasily Levchenko]

Does it reproducible with VBox 4.1.12? If yes, please attach the log for problematic session?