Any changes in kernels the last month (Iptables related)

[Doug Smythies]

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 hastighedstest.tdc.dk 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