默认还开户了防火墙：
[root@localhost ~]# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
92 8671 ACCEPT all – * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
0 0 ACCEPT icmp – * * 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT all – lo * 0.0.0.0/0 0.0.0.0/0
1 56 ACCEPT tcp – * * 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22
573 65158 REJECT all – * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 REJECT all – * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited