Ubuntu – DHCPv6 not working when UFW is enabled (Ubuntu 16.04 LTS)

dhcpv6isc-dhcpUbuntuufw

So, as the title says, I setup a isc-dhcp-server for DHCPv6, which is working as long as UFW is disabled.

Once enabled, though I have all the necessary rules in place, and UFW is enabled for v6, it stops working.

My rules are:

xxx@deadpool:/etc/ufw# grep '546\|547' *
after6.rules:-A ufw6-after-input -p udp --dport 546 -j ufw6-skip-to-policy-input
after6.rules:-A ufw6-after-input -p udp --dport 547 -j ufw6-skip-to-policy-input    
before6.rules:-A ufw6-before-input -p udp -s fe80::/10 --sport 547 -d fe80::/10 --dport 546 -j ACCEPT

I found two related but fixed bugs on launchpad:
https://bugs.launchpad.net/ubuntu/+source/ufw/+bug/947416
https://bugs.launchpad.net/ubuntu/+source/ufw/+bug/1007326

Any ideas?

Best Answer

I see an existing rule for a DHCP client:

# allow dhcp client to work
-A ufw6-before-input -p udp -s fe80::/10 --sport 547 -d fe80::/10 --dport 546 -j ACCEPT

I think you need to reverse the source/destination ports for your *server:

# dhcp server
-A ufw6-before-input -p udp -s fe00::/7 --sport 546 -d fe00::/7 --dport 547 -j ACCEPT
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