[pkg-lxc-devel] Bug#832090: Bug#832090: lxc: dhcp fails due to invalid UDP checksum

[Evgeni Golov]

Hi Lucas,

On Fri, Jul 22, 2016 at 09:52:47AM +0200, Lucas Nussbaum wrote:

> When booting containers, DHCP fails to get an IP due to invalid
> UDP checksums.

Interesting. Esp as I cannot reproduce it here.

> I use the lxc-net-based setup as described in
> https://wiki.debian.org/LXC/SimpleBridge ("using lxc-net").
> This creates a lxcbr0 bridge.
> When starting up, the containers' veth device is correctly attached to
> the bridge.
> However, it fails to get an IP using DHCP.

I create my test-setup as follows:

# create a new sid vm
# apt install lxc
# echo USE_LXC_BRIDGE=true > /etc/default/lxc-net
# service lxc-net restart
# cat <<EOF >/etc/lxc/default.conf
lxc.network.type = veth
lxc.network.link = lxcbr0
lxc.network.flags = up
lxc.network.hwaddr = 00:16:3e:xx:xx:xx
EOF

And now I create a container:
# lxc-create -t download -n debian-jessie -- -d debian -r jessie -a amd64
# lxc-start -n debian-jessie

Now I see an IP from 10.0.3.0/24 in lxc-ls -f and in ip a called from inside the container.

> If, on the host, I disable checksum offloading using:
> sudo ethtool -K vethILRWN4 tx off

My checksumming was on during the above tests.

Greets
Evgeni