1、检查路由表：正常

 route -n 

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         172.19.224.1    0.0.0.0         UG    0      0        0 eth0
3.0.1.0         0.0.0.0         255.255.255.0   U     0      0        0 tun0
10.254.253.0    0.0.0.0         255.255.255.0   U     0      0        0 tun0
66.1.77.0       0.0.0.0         255.255.255.0   U     0      0        0 tun0
172.19.224.0    0.0.0.0         255.255.240.0   U     0      0        0 eth0

2、检查防火墙

iptables --line-numbers -L

Chain INPUT (policy ACCEPT)
num  target     prot opt source               destination

Chain FORWARD (policy ACCEPT)
num  target     prot opt source               destination

Chain OUTPUT (policy ACCEPT)
num  target     prot opt source               destination
1    SANGFOR_VIRTUAL  all  --  anywhere             anywhere

Chain SANGFOR_VIRTUAL (1 references)
num  target     prot opt source               destination
======== 敏感信息=============
103  DROP       all  --  anywhere             anywhere

从结果中可发现SANGFOR_VIRTUAL 自定义链中只放行了指定网络权限，删除最后一条规则或清空 SANGFOR_VIRTUAL规则即可访问外网。

#清空 SANGFOR_VIRTUAL
iptables -F  SANGFOR_VIRTUAL