I have a really odd issue with Flow Rules: it seems that they do not work?!
If I put anything but accept; at the end of my rules, traffic gets blocked.
I started using statements that included ipsrc and ipdest, none of these rules worked. So I came up with this example: it should allow ICMP (0x01), UDP (0x11), and TCP (0x06):
You’re blocking ARP, which is how IPv4 addresses are resolved to hardware (MAC) addresses on a network. You’ll note that the default rule set includes this:
#
# Allow only IPv4, IPv4 ARP, and IPv6 Ethernet frames.
#
drop
not ethertype ipv4
and not ethertype arp
and not ethertype ipv6
;
accept;
What this does is drop anything that’s not IPv4, IPv6 or ARP. Specifying ICMP is not required as ICMP is already IPv4 or IPv6.