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Description of problem:
By default dhcp6 responses are not allowed by default. This prevents network or NeworkManager from leasing dhcp by default if iptables is used in preference to firewalld. 

The following rules should be added.
-A INPUT -s fe80::/16 -p udp -m udp --dport 546 -j ACCEPT
-A INPUT -s fe80::/16 -p tcp -m tcp --dport 546 -j ACCEPT

Such that:

*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p ipv6-icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT
-A INPUT -s fe80::/16 -p udp -m udp --dport 546 -j ACCEPT
-A INPUT -s fe80::/16 -p tcp -m tcp --dport 546 -j ACCEPT
-A INPUT -j REJECT --reject-with icmp6-adm-prohibited
-A FORWARD -j REJECT --reject-with icmp6-adm-prohibited
COMMIT

(In reply to William Brown from comment #0)
> Description of problem:
> The following rules should be added.
> -A INPUT -s fe80::/16 -p udp -m udp --dport 546 -j ACCEPT
> -A INPUT -s fe80::/16 -p tcp -m tcp --dport 546 -j ACCEPT

DHCPv6 uses UDP messages only. Also the prefix length of link local address is 64, not 16.

I've changed this in Fedora.
http://pkgs.fedoraproject.org/cgit/iptables.git/commit/?id=69f9a1a33c1a7152cb7d4473b6e7580d147b3e8a

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHBA-2015-2103.html