[CentOS] how to capture packets that was forwarded

hello, the topology is like this:

centos v0:eth1 <------> centos v0: eth2 fc00:2:3:4::1 fc00:2:3::4

i turned the packet forwarding

ping6 -i eth2 fc00:2:3:4::1 the output is

PING fc00:2:3:4::1(fc00:2:3:4::1) from fc00:2:3::5 eth2: 56 data bytes

From fc00:2:3::4 icmp_seq=1 Destination unreachable: Administratively

prohibited

From fc00:2:3::4 icmp_seq=2 Destination unreachable: Administratively

prohibited

From fc00:2:3::4 icmp_seq=3 Destination unreachable: Administratively

prohibited

From fc00:2:3::4 icmp_seq=4 Destination unreachable: Administratively

prohibited

why the box do not forwarding icmp packets to eth2? and how to set forwarding rules on centos 6.3? Thanks