Like in IPv4 clients behind a router can be hided by using IPv6 masquerading (hide/overlap NAT), e.g.

# ip6tables -t nat -A POSTROUTING -o sixxs -s fec0::/64 -j MASQUERADE

A dedicated public IPv6 address can be forwarded to an internal IPv6 address, e.g.

# ip6tables -t nat -A PREROUTING -d 2001:db8:0:1:5054:ff:fe01:2345 -i sixxs -j DNAT --to-destination fec0::5054:ff:fe01:2345

A dedicated specified port can be forwarded to an internal system, e.g.

# ip6tables -t nat -A PREROUTING -i sixxs -p tcp --dport 8080 -j DNAT --to-destination [fec0::1234]:80