I've already tried iptables command and it didn't work for me.
The reason I need to access metadata server is for cloudpipe instance, get 'autorun.sh' from the server.

Here's my 'iptables -L' result. "cloud02" the hostname of API Server.
Something wrong? 

Chain INPUT (policy DROP)
target     prot opt source               destination
ACCEPT     udp  --  anywhere             anywhere            udp dpt:domain
ACCEPT     tcp  --  anywhere             anywhere            tcp dpt:domain
ACCEPT     udp  --  anywhere             anywhere            udp dpt:bootps
ACCEPT     tcp  --  anywhere             anywhere            tcp dpt:bootps
ACCEPT     all  --  anywhere             anywhere
ACCEPT     icmp --  anywhere             anywhere            icmp any
ACCEPT     tcp  --  anywhere             anywhere            state NEW tcp dpt:ftp
ACCEPT     tcp  --  anywhere             anywhere            state NEW tcp dpt:ssh
ACCEPT     tcp  --  anywhere             anywhere            state NEW tcp dpt:telnet
ACCEPT     tcp  --  anywhere             anywhere            state NEW tcp dpt:smtp
ACCEPT     tcp  --  anywhere             anywhere            state NEW tcp dpt:www
DROP       all  --  anywhere             anywhere            state INVALID
ACCEPT     all  --  anywhere             anywhere            state RELATED,ESTABLISHED
ACCEPT     tcp  --  anywhere             cloud02             tcp dpt:ssh
ACCEPT     udp  --  anywhere             anywhere            udp dpt:ntp
nova_input  all  --  anywhere             anywhere
ACCEPT     icmp --  anywhere             anywhere
REJECT     tcp  --  anywhere             anywhere            reject-with tcp-reset
REJECT     all  --  anywhere             anywhere            reject-with icmp-port-unreachable

Chain FORWARD (policy DROP)
target     prot opt source               destination
nova-local  all  --  anywhere             anywhere
ACCEPT     all  --  anywhere             anywhere
ACCEPT     all  --  anywhere             anywhere
ACCEPT     udp  --  anywhere             10.0.0.2            udp dpt:openvpn
ACCEPT     all  --  anywhere             192.168.122.0/24    state RELATED,ESTABLISHED
ACCEPT     all  --  192.168.122.0/24     anywhere
ACCEPT     all  --  anywhere             anywhere
REJECT     all  --  anywhere             anywhere            reject-with icmp-port-unreachable
REJECT     all  --  anywhere             anywhere            reject-with icmp-port-unreachable
DROP       all  --  anywhere             anywhere            state INVALID
ACCEPT     all  --  anywhere             anywhere            state RELATED,ESTABLISHED
TCPMSS     tcp  --  anywhere             anywhere            tcp flags:SYN,RST/SYN TCPMSS clamp to PMTU
nova_forward  all  --  anywhere             anywhere

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination
nova-local  all  --  anywhere             anywhere
DROP       all  --  anywhere             anywhere            state INVALID
ACCEPT     all  --  anywhere             anywhere            state RELATED,ESTABLISHED
nova_output  all  --  anywhere             anywhere

Chain nova-fallback (1 references)
target     prot opt source               destination
DROP       all  --  anywhere             anywhere

Chain nova-inst-1 (1 references)
target     prot opt source               destination
DROP       all  --  anywhere             anywhere            state INVALID
ACCEPT     all  --  anywhere             anywhere            state RELATED,ESTABLISHED
nova-sg-1  all  --  anywhere             anywhere
ACCEPT     udp  --  10.0.0.1             anywhere            udp spt:bootps dpt:bootpc
ACCEPT     all  --  10.0.0.0/26          anywhere
nova-fallback  all  --  anywhere             anywhere

Chain nova-local (2 references)
target     prot opt source               destination
nova-inst-1  all  --  anywhere             10.0.0.3

Chain nova-sg-1 (1 references)
target     prot opt source               destination

Chain nova_forward (1 references)
target     prot opt source               destination

Chain nova_input (1 references)
target     prot opt source               destination
ACCEPT     tcp  --  anywhere             cloud02             tcp dpt:8649
ACCEPT     udp  --  anywhere             cloud02             udp dpt:8649
ACCEPT     tcp  --  anywhere             cloud02             tcp dpt:www
ACCEPT     tcp  --  anywhere             cloud02             tcp dpt:https
ACCEPT     tcp  --  anywhere             cloud02             tcp dpt:3333
ACCEPT     tcp  --  anywhere             cloud02             tcp dpt:8773
ACCEPT     tcp  --  anywhere             cloud02             tcp dpt:6379
ACCEPT     tcp  --  anywhere             cloud02             tcp dpt:mysql
ACCEPT     tcp  --  anywhere             cloud02             tcp dpt:4369
ACCEPT     tcp  --  anywhere             cloud02             tcp dpt:amqp
ACCEPT     tcp  --  anywhere             cloud02             tcp dpt:53284
ACCEPT     tcp  --  10.0.0.0/12          anywhere            tcp dpt:domain
ACCEPT     udp  --  10.0.0.0/12          anywhere            udp dpt:domain
ACCEPT     udp  --  anywhere             anywhere            udp dpt:bootps
ACCEPT     tcp  --  anywhere             cloud02             tcp dpt:ldap

Chain nova_output (1 references)
target     prot opt source               destination