[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]

Re: [libvirt] problem with nwfilter and ip6tables



On 11/21/2011 08:46 AM, Reinier Schoof wrote:

Going back to the original email:

Hi,

I'm investigating using the nwfilter-functionality of libvirt to give my clients the possibility to block ports of their VPSes. The same mechanism allows me to restrict the outgoing traffic a VPS is generating. In the end, I want to restrict MAC, IPv4 and IPv6 traffic, while the client can also restrict traffic to UDP and TCP.

All goes well, until I want to restrict the UDP/TCP traffic to certain IPv6 addresses. Where iptables shows the IPv4-restriction I've put up, ip6tables doesn't show anything. In the logs, I only see some ip6tables -D, -X and -F commands failing, which is expected when libvirt tries to delete/flush rules that were never there.

I've built my nwfilter containing the following IPv6-rules, which I for instance reference once for all the TCP-ports which should be open.

<!-- Allow established traffic -->
<filter name='ipv6-allow-statefull' chain='ipv6'>
<rule action='accept' direction='in' priority='500'>
<all state='ESTABLISHED'/>
</rule>
<rule action='accept' direction='out' priority='500'>
<all state='ESTABLISHED,RELATED'/>
</rule>
</filter>

Replace with

<filter name='ipv6-allow-statefull' chain='root'>
<uuid>d7ca42fe-a2f5-6491-cdee-10d8a0956772</uuid>
<rule action='accept' direction='in' priority='100'>
<all-ipv6 state='ESTABLISHED'/>
</rule>
<rule action='accept' direction='out' priority='100'>
<all-ipv6 state='ESTABLISHED,RELATED'/>
</rule>
</filter>

<!-- Allow TCP in $PORT -->
<filter name='ipv6-allow-create-state-by-port' chain='ipv6'>
<rule action='accept' direction='in' priority='500'>
<tcp state='NEW' dstportstart='$PORT'/>
</rule>
<rule action='accept' direction='in' priority='500'>
<udp state='NEW' dstportstart='$PORT'/>
</rule>
</filter>

Replace with

<filter name='ipv6-allow-create-state-by-port' chain='root'>
<uuid>ff97e825-712d-6b1a-c5d1-46fe635f9dd6</uuid>
<rule action='accept' direction='in' priority='500'>
<tcp-ipv6 state='NEW' dstportstart='$PORT'/>
</rule>
<rule action='accept' direction='in' priority='500'>
<udp-ipv6 state='NEW' dstportstart='$PORT'/>
</rule>
</filter>

<!-- Allow IPv6 traffic from $RANGE -->
<filter name='ipv6-allow-create-state-by-range' chain='ipv6'>
<rule action='accept' direction='out' priority='500'>
<ipv6 srcipaddr='$RANGE' srcipmask='64'/>
</rule>
</filter>

This probably should either be direction='in' or you may want to replace srcipaddr and srcipmask with dstipaddr and dstipmask.

Replace with

<filter name='ipv6-allow-create-state-by-range' chain='root'>
<uuid>6e738070-9505-730d-14e6-ee01a6eb5885</uuid>
<rule action='accept' direction='in' priority='500'>
<all-ipv6 srcipaddr='$RANGE' srcipmask='62'/>
</rule>
</filter>

You may want to add state='NEW' to the rule as well.

<!-- Drop all other IPv6 traffic -->
<filter name='ipv6-drop-stateless' chain='ipv6'>
<rule action='drop' direction='inout' priority='999'>
<all/>
</rule>
</filter>

Replace with

<filter name='ipv6-drop-stateless' chain='root'>
<uuid>4377aca7-18fb-b373-4462-4ee2ba3db7cd</uuid>
<rule action='drop' direction='inout' priority='999'>
<all-ipv6/>
</rule>
</filter>


You have to change the chain to 'root' and the protocol in the rules has to be tcp-ipv6, all-ipv6 etc. for ipv6 traffic. The reason is that most of these rules could be applied to either iptables or ip6tables and the network filtering system needs some more 'hints' whether it is indeed an ipv6 rule so it create ip6tables commands versus iptables commands.

I hope this helps.

'ip6tables -L -n' here now shows:

Chain FI-vnet0 (1 references)
target     prot opt source               destination
RETURN all ::/0 ::/0 state RELATED,ESTABLISHED RETURN all ::/0 ::/64 state ESTABLISHED ctdir ORIGINAL
DROP       all      ::/0                 ::/0

Chain FO-vnet0 (1 references)
target     prot opt source               destination
ACCEPT all ::/0 ::/0 state ESTABLISHED ACCEPT tcp ::/0 ::/0 tcp dpt:90 state NEW ACCEPT udp ::/0 ::/0 udp dpt:90 state NEW ACCEPT all ::/64 ::/0 state NEW,ESTABLISHED ctdir REPLY
DROP       all      ::/0                 ::/0

Chain HI-vnet0 (1 references)
target     prot opt source               destination
RETURN all ::/0 ::/0 state RELATED,ESTABLISHED RETURN all ::/0 ::/64 state ESTABLISHED ctdir ORIGINAL
DROP       all      ::/0                 ::/0



   Stefan

I use a similar approach for my IPv4 firewall, and it works perfectly. When I use these IPv6 rules, all IPv6 traffic is apparently dropped, but it's hard to debug when the result of this config is abscent in ip6tables.

I'm using these version of software on debian 6.0 squeeze:
virsh # version
Compiled against library: libvir 0.9.2
Using library: libvir 0.9.2
Using API: QEMU 0.9.2
Running hypervisor: QEMU 0.15.0

Does anyone have any clues? Thanks in advance!

Regards,

Reinier Schoof



[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]