ubuntu - linux服务器双网卡连接到路由器共享网络，应该如何配置NAT？

Question

服务器是ubuntu server 12.04 i386，装有双网卡。其中eth0连接到外网，eth1连接到路由器的WAN端口。想创建一个共享wifi，使其他设备都能通过服务器上网

cat /etc/network/interfaces

auto lo  
iface lo inet loopback  
#连接到外网
auto eth0  
iface eth0 inet static  
address 212.114.20.78  
netmask 255.255.255.0  
gateway 212.114.20.126  
dns-nameservers 212.114.0.242 8.8.8.8  
#连接到路由器
auto eth1  
iface eth1 inet static  
address 192.168.1.254  
netmask 255.255.255.0

route -n

Destination     Gateway         Genmask         Flags Metric Ref      Use Iface  
0.0.0.0         212.114.20.126  0.0.0.0         UG    100    0        0   eth0  
192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0   eth1  
212.114.20.0    0.0.0.0         255.255.255.0 U     0      0        0   eth0

路由器设置如下：

Answer 1

echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -t nat -A POSTROUTING -s 192.168.0.0/24 -j MASQUERADE

Also, what is the routing table of your server (route -n output).

Answer 2

• Confirm that the physical wiring is correct, whether it can ping pass gateway and dns, and whether eth1 is connected to the WAN port (non-LAN port)
• Modify /etc/network/interfaces (corresponding to the changes to the eth0 part above)
• Make the modification effective: sudo /etc/init.d/networking restart
• Set the router as shown in the picture above and enable the router DHCPservice
• sudoExecute the following command:

/sbin/iptables -F 
/sbin/iptables -X 
/sbin/iptables -Z 
/sbin/iptables -F -t nat 
/sbin/iptables -X -t nat 
/sbin/iptables -Z -t nat 
/sbin/iptables -P INPUT ACCEPT
/sbin/iptables -P OUTPUT ACCEPT 
/sbin/iptables -P FORWARD ACCEPT 
/sbin/iptables -t nat -P PREROUTING ACCEPT 
/sbin/iptables -t nat -P POSTROUTING ACCEPT 
/sbin/iptables -t nat -P OUTPUT ACCEPT 
echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -t nat -A POSTROUTING -s 192.168.1.0/24 -j MASQUERADE

• Add iptables -t nat -A POSTROUTING -s 192.168.1.0/24 -j MASQUERADE to /etc/rc.local
• If it still doesn’t work, check whether you followed Evian’s answers and comments