Linux dual-Network Policy Routing script instance-(better)

Linux dual-Network Policy Routing script instance-(better)-Linux Enterprise Application-Linux server application information, the following is a detailed description. The dual-network architecture is much more complex than the single-network architecture.

First install the Linux advanced route package and use the ip commands in it.
# Apt-get install iproute

Create two tables first

Modify
/Etc/iproute2/rt_tables:

Add t1 user-defined number 10
Add t2 custom number 20

Code:
########################################
#
# Reserved values
#
255 local
254 main
253 default
0 unspec
#
# Local
#
10 T1
20 T2
########################################

Then copy the cnc_1_net and ctc_1_net in the attachment to the/etc directory, because the following script will be used.
Cnc_w.net is the ip address segment of China Netcom.
Ctc_w.net is the ip address segment of China Telecom.

We need to edit a script.

########################################

#! /Bin/sh

# IF1 is the network interface of China Netcom
IF1 = "eth0"

# IF2 is an Intranet Network Interface
IF2 = "eth2"

# IF0 is the network interface of China Telecom
IF0 = "eth1"

# IP1 is the IP address of China Netcom
IP1 = "221.8.60.54"

# IP2 is the Telecom IP Address
IP2 = "222.1611.186"

# P1 is the gateway of China Netcom
P1 = "221.8.60.53"

# P2 is the gateway of China Telecom
P2 = "222.1611.185"


# P1_NET is the network segment of China Netcom. The netmask 30 indicates that four ip addresses are assigned. If the ip address is 8, 29 is required.
P1_NET = "221.8.60.52/30"

# P2_NET is the China Telecom CIDR Block
P2_NET = "222.1611.184/30"

# P0_NET is an intranet segment
P0_NET = "192.168.0.0/24"


# Set basic firewall

Echo "1">/proc/sys/net/ipv4/ip_forward
Echo 8000>/proc/sys/net/ipv4/ip_conntrack_max

Modprobe iptable_filter
Modprobe ip_tables
Modprobe iptable_nat
Modprobe ip_conntrack
Modprobe ip_nat_ftp
Modprobe ip_conntrack_ftp
Modprobe ip_nat_irc
Modprobe ip_conntrack_irc
Modprobe ipt_MASQUERADE

Modprobe ipt_REJECT
Modprobe ipt_limit


Iptables-F
Iptables-t nat-F
Iptables-P INPUT DROP
Iptables-P FORWARD ACCEPT
Iptables-P OUTPUT ACCEPT

Iptables-a input-m state -- state ESTABLISHED, RELATED-j ACCEPT
Iptables-a input-p tcp -- dport 22-m state -- state NEW-j ACCEPT
Iptables-a input-I lo-j ACCEPT
Iptables-a forward-p tcp -- tcp-flags SYN, rst syn-j TCPMSS -- clamp-mss-to-pmtu
Iptables-a input-p icmp -- icmp-type echo-request-m limit -- limit 1/s-j ACCEPT
Iptables-t nat-a postrouting-s $ P0_NET-o $ IF1-j MASQUERADE
Iptables-t nat-a postrouting-s $ P0_NET-o $ IF2-j MASQUERADE

# Setting Policy Routing

Ip route flush table T1
Ip route flush table T2

Ip rule list | grep T | while read line; do
POS4 = 'echo $ line | awk \ '{print $4 }\''
If ["$ POS4" = "to"]
Then
DST = 'echo $ line | awk \ '{print $5 }\''
RT = 'echo $ line | awk \ '{print $7 }\''
Ip rule del to $ DST table $ RT
Fi
If ["$ POS4" = "lookup"]
Then
SRC = 'echo $ line | awk \ '{print $3 }\''
RT = 'echo $ line | awk \ '{print $5 }\''
Ip rule del from $ SRC table $ RT
Fi
Done

If [! -Z $ IP1]
Then
Ip route replace $ P1_NET dev $ IF1 src $ IP1

Ip route add $ P1_NET dev $ IF1 src $ IP1 table T1
Ip route add $ P0_NET dev $ IF0 table T1
Ip route add 127.0.0.0/8 dev lo table T1

Ip route add $ P1_NET dev $ IF1 table T2

Ip route replace default via $ P1 dev $ IF1 table T1

Ip rule add from $ IP1 table T1

WAN_RT1 = "nexthop via $ P1 dev $ IF1 weight 1"
Fi
If [! -Z $ IP2]
Then
Ip route replace $ P2_NET dev $ IF2 src $ IP2

Ip route add $ P2_NET dev $ IF2 src $ IP2 table T2
Ip route add $ P0_NET dev $ IF0 table T2
Ip route add 127.0.0.0/8 dev lo table T2

Ip route add $ P2_NET dev $ IF2 table T1

Ip route replace default via $ P2 dev $ IF2 table T2

Ip rule add from $ IP2 table T2

WAN_RT2 = "nexthop via $ P2 dev $ IF2 weight 1"
Fi

WAN_RT3 = "$ WAN_RT1 $ WAN_RT2"

# Use China Netcom as the default gateway. For China Telecom, change $ WAN_RT1 to $ WAN_RT2.
Ip route replace default scope global $ WAN_RT1

# Use two gateways for Load Balancing (generally not needed)
# Ip route replace default equalize scope global $ WAN_RT3

Ip route flush cache

If [-s/etc/ctc_1_net]
Then
While read LINE
Do
Case $ LINE in
\\#*);;
*)
Ip rule add to $ LINE table T2
;;
Esac
Done </etc/ctc_javasnet
Fi

If [-s/etc/cnc_1_net]
Then
While read LINE
Do
Case $ LINE in
\\#*);;
*)
Ip rule add to $ LINE table T1
;;
Esac
Done </etc/cnc_1_net
Fi

Ip route flush cache