[libvirt] [PATCH] nwfilter: enable bridge netfilter calls via proc filesystem

[Stefan Berger]

  On 09/22/2010 02:49 PM, Daniel P. Berrange wrote:
> On Wed, Sep 22, 2010 at 02:19:31PM -0400, Stefan Berger wrote:
>>   On a recent installation of FC13, the filtering of IP/IPv6 using
>> iptables/ip6tables traffic did not work since the proc filesystem
>> entries /proc/sys/net/bridge/bridge-nf-call-iptables and
>> /proc/sys/net/bridge/bridge-nf-call-ip6tables contained a zero each and
>> no traffic went into the FORWARD chain. The patch below makes sure that
>> if iptables or ip6tables are being used by the nwfilter driver that a
>> '1' is written into the relevant proc filesystem entry so that the
>> traffic goes into the FORWARD chain.
> NACK to this. We need to figure out how to make this filtering
> work with them set to 0. The change to set them to 0 by default
> is explicitly done for the benefit of virtualization, otherwise
> guest traffic gets blocked by regular host firewall rules which
> is not desirable. eg run system-config-firewall and block ssh
> port on the host, and you've blocked it on all the guests too :-(
>
The ssh port blocking for the host is a rule that goes into the INPUT 
table. That is independent of what libvirt does with the FORWARD table 
and this host rule would not influence the guest rules and vice versa. 
Traffic destined to bridged guests will NOT go through the INPUT table, 
only traffic from guests towards their own host will go through it.

Regards,
    Stefan


> Daniel