[CentOS] CentO 8 and nftables default policy

Sat Apr 18 11:03:55 UTC 2020
Alessandro Baggi <alessandro.baggi at gmail.com>

Il 17/04/20 11:01, Alessandro Baggi ha scritto:
> Hi list,
> I'm studying nftables. I'm using CentOS 8.1 (Gnome) and I disabled 
> firewalld. I noticed that a default policy is created with tables and 
> chains probably for firewalld.
> So I created a .nft script where I stored my rules with a flush for 
> previous ruleset, then saved on /etc/sysconfig/nftables.conf and the 
> enabled nftables service.
> Running the script with nft -f script.nft all work as expected but 
> when rebooting, running nft list ruleset I find my rules and the 
> default policy (chains and tables) that I would not have in my 
> configuration.
> My nftables.conf contains only my ruleset.
> For example, running nft list tables I found several default tables like:
> table ip filter
> table ip6 filter
> table bridge filter
> table ip nat
> table ip mangle
> So probably there is something that is applying its policy but I 
> ignore what is.
> Can someone point me in the right direction?
> Thank you in advance.
Hi have not received any replies but I tried to investigate. After 
checking configuration files in my system I supposed that this could 
caused by a daemon, so I found that libvirtd push some rules.

running virsh nwfilter-list I get:

  UUID                                  Nome
  34fe8cba-af99-4438-8efc-b135143425e2  allow-arp
  dc110112-3824-4cf3-946f-ba6e15cd29c3  allow-dhcp
  fecc383a-bab5-465d-a5be-98834fb626ce  allow-dhcp-server
  761e7132-8738-47c2-8101-275d6fd6a347  allow-incoming-ipv4
  d37b017f-8f21-4ad0-9fa6-052a5cb1ed2e  allow-ipv4
  a8c740d5-328c-452e-bae7-9828c54f95b7  clean-traffic
  296bdfad-11d9-4aa0-9817-4656ef2be6e5  clean-traffic-gateway
  69215a61-bff5-482a-b913-589bb1ce18f2  no-arp-ip-spoofing
  70c61f0a-c005-407f-843d-d13c2495f05d  no-arp-mac-spoofing
  386cd2f4-7272-43e2-ba1f-80cb3518649c  no-arp-spoofing
  9117fa21-e3d6-4c32-9cdf-af97ebd6599e  no-ip-multicast
  7a964470-4f74-4eef-9fec-a0e9a79e168d  no-ip-spoofing
  8c9e45a3-5d44-4641-b23d-eded5c1f1632  no-mac-broadcast
  82dcd4f0-f55a-43ad-b520-d4c8d4bf37cd  no-mac-spoofing
  bdd0ba54-7ce0-4a2c-9c25-c24072d364ba  no-other-l2-traffic
  fc50783e-d32b-42ba-8380-7576c4388244  no-other-rarp-traffic
  edfc1bb3-b325-4f8d-8c5b-423e55da66eb  qemu-announce-self
  8556bd82-dc97-47b0-b573-5986ebbad3b2  qemu-announce-self-rarp

If I will remove these libvirt filters I will get errors?

Thank you in advance.