[gentoo-user] Forwarding bug in kernel 3.14.1 and 3.14.2

[gentoo-user] Forwarding bug in kernel 3.14.1 and 3.14.2

[Timur Aydin]

Hi,

To all folks that use their gentoo linux PC as their internet
router/gateway, don't upgrade your kernel to 3.14.1 or 3.14.2.

These versions have a bug related to IP packet forwarding. Internet
upload speed for the NAT clients gets extremely slow (in the order of
10Kbps), which download speed remain unaffected. I have spent the entire
weekend trying to debug the slow upload issue. I tried different NIC's,
different cables, different clients etc, problem was still occurring.
Upload/download from the Gentoo linux PC is fine, but any NAT client
exhibits the slow upload speed problem. I also suspected that somehow
the MSS clamping with iptables doesn't work, that wasn't the problem
either, because even with all tables flushed and only IP MASQUERADING in
place the problem was there.

I finally found a bug report that explains the symtom:

http://www.spinics.net/lists/netdev/msg280571.html

I then downgraded the kernel to 3.13.11, which fixed the problem. So,
all of you guys using your Gentoo PC as your internet gateway, keep
3.13.11 around for a while.

-- 
Timur

Re: [gentoo-user] Forwarding bug in kernel 3.14.1 and 3.14.2

[Michael Orlitzky]

On 05/05/2014 06:58 AM, Timur Aydin wrote:
> 
> I finally found a bug report that explains the symtom:
> 
> http://www.spinics.net/lists/netdev/msg280571.html
> 
> I then downgraded the kernel to 3.13.11, which fixed the problem. So,
> all of you guys using your Gentoo PC as your internet gateway, keep
> 3.13.11 around for a while.
> 

Thanks for the warning. You should file a Gentoo bug for this -- the
maintainers take the open bugs into consideration when stabilizing
things, so an open bug report for something this critical might prevent
the 3.14.x series from going stable for a while.

Not that you shouldn't post it here as well, I've personally been saved
from disaster twice by posts like these.