id,summary,reporter,owner,description,type,status,component,version,resolution,keywords,cc,guest,host
13662,UDP port mapping disappears from a host outer interface,TriAnMan,,"I have a Windows 7 host with CentOS 7 guest with ""--hpet on"" and a NAT network interface.
Guest has a DHCP server (bind9) which I want to use in my network.
So I have a port forwarding configured like this: http://screencast.com/t/815d9MGK3

When I start my guest box everything is ok:
I see a listening port and nslookup resolves names.
{{{
C:\>netstat -a -b -n

Active Connections

  Proto  Local Address          Foreign Address        State
  TCP    0.0.0.0:53             0.0.0.0:0              LISTENING
 [VBoxHeadless.exe]
  TCP    0.0.0.0:80             0.0.0.0:0              LISTENING
 [VBoxHeadless.exe]

....

  UDP    0.0.0.0:53             *:*
 [VBoxHeadless.exe]

....
}}}
But in a couple of minutes (5-15) UDP mapping disappears. There is no any related error message in the VBox.log or VBoxStartup.log. nslookup doesn't resolve names. Netstat shows no UDP port opened.

If I try to delete and add a UDP mapping on this running box I receive an error:
http://screencast.com/t/RTywcC6GPA
or an error about memory can't be readed.
and a guest box goes into an aborted state.

This behavior doesn't depend on Windows Firewall state. I have no antiviruses running but has the Avast installed.

I have just found more reproducible behavior.

Box setup is the same.

Start a guest-box.

On the host use:
{{{
nslookup example.com 192.168.1.151
}}}
and then
{{{
nslookop example.com 127.0.0.1
}}}
after that if I use
{{{
nslookup example.com 192.168.1.151
DNS request timed out.
    timeout was 2 seconds.
Server:  UnKnown
Address:  192.168.1.151
DNS request timed out.
    timeout was 2 seconds.
}}}
but 
{{{
nslookop example.com 127.0.0.1
}}}
still working and
{{{
C:\>netstat -a -b -n

Active Connections

  Proto  Local Address          Foreign Address        State
  TCP    0.0.0.0:53             0.0.0.0:0              LISTENING
 [VBoxHeadless.exe]
  TCP    0.0.0.0:80             0.0.0.0:0              LISTENING
 [VBoxHeadless.exe]

....

  UDP    0.0.0.0:53             *:*
 [VBoxHeadless.exe]

....
}}}
seems to be ok.
In this case sometimes I can delete and add a UDP mapping for 53 port and nslookup example.com 192.168.1.151 becomes working again. Or sometimes settings window for a guest-box isn't appearing.
P.S.: 192.168.1.151 is my host LAN interface.",defect,closed,network/NAT,VirtualBox 4.3.20,duplicate,udp port mapping,,Linux,Windows