Any changes in kernels the last month (Iptables related)

Joseph Salisbury joseph.salisbury at
Fri Sep 5 16:21:48 UTC 2014

On 09/05/2014 09:58 AM, Doug Smythies wrote:
> On 2014.09.05 01:10 Kim Emax wrote:
>> I was wondering if there´s been any changed in the later kernels? 
>> I´m using a ubuntu server with tow nics as a router, firewall, DHCP etc.
>> The last month out of nowhere and without any changes (other > than regular
>> updates from apt) my LAN has been fucked on upload (0.07mbit), while the WAN
>> has +40Mbit. I´ve rebooted switches and WLAN > router, changed the LAN nic and
>> has a laptop directly to the router, no luck.
>> By changing in the iptables rules i´ve managed to tweak the LAN upload to 1-2mbit,
>> still works really bad on LAN though. Taking a test > at shows
>> NO speed at first, then after a while it goes up a bit up to 3mbit, then falls back
>> and stays around > 1mbit. Wierd behaviour.
>> Current Kernel: 3.2.0-67-generic, Ubuntu 12.04
> Yes, the same thing happened to my Ubuntu 12.04 server which is my main router to
> my LAN with the same kernel.
> The lost time and frustration trying to figure it out was staggering.
> I also suffered significant collateral damage.
> In my case the root issue was MTU and some new enforcement thereof, giving a lot
> ICMP packets saying something like:
> "ICMP port unreachable, packet too long and don't fragment bit is set"
> O.K. so the real root issue is that some clients (windows clients and only a
> couple of NIC cards (it seems)) ignore the MTU and send larger packets.
> Anyway, and in my case, the issue is resolved in the next kernel, or by going back to the previous kernel.
> Linux doug-64 3.2.0-68-generic #102-Ubuntu SMP Tue Aug 12 22:02:15 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
> ... Doug

Hi Doug,

When you say it was resolved by going to the next kernel, do you mean
you apply the latest updates and the next kernel is what came in with
that(3.2.0-68)?  Or do you mean the next kernel that is in the next
Ubuntu release like Trusty or Utopic. Does the bug exists in 3.2.0-67
but not 3.2.0-68?

Kim, it would be really helpful if you can open a Lauchpad bug report
against the kernel.  That will let us review your logs, version info,
etc.  You can do this by running the following from a terminal window:
'ubuntu-bug linux'.  If the bug is in fact fixed in 3.2.0-68, the
easiest fix would be to just apply the latest updates.



More information about the ubuntu-server mailing list