CLI: Example for Configuring Internet Users of Different ISPs to Access the Same Public IP address of a Server on a Dual-Egress Intranet (Sticky Load Balancing)

This section provides an example for configuring internet users of different ISPs to access the same public IP address of a server on a dual-egress intranet in the case of sticky load balancing.

Networking Requirements

As shown in Figure 1, an enterprise deploys a FW at the network border as the security gateway that connects to the Internet over two ISP networks. The intranet FTP server applies a public IP address (1.1.10.10) only from ISP1 to provide services for Internet users. Internet users on ISP1 and ISP2 networks must use this public IP address to access the FTP server.

Figure 1 Networking diagram for configuring NAT policy on a dual-egress intranet in the case of sticky load balancing

Data Planning

Item	Data	Description
GigabitEthernet 0/0/1	IP address: 1.1.1.1/24 Security zone: untrust1	Obtain the public IP address from the ISP.
GigabitEthernet 0/0/7	IP address: 2.2.2.2/24 Security zone: untrust2	Obtain the public IP address from the ISP.
GigabitEthernet 0/0/2	IP address: 10.2.0.1/24 Security zone: DMZ	-
NAT policy	Policy name: policy1 Source zones: untrust1 and untrust2 Public address: 1.1.10.10 Destination address pool: 10.2.0.8	The NAT policy converts traffic whose destination address is 1.1.10.10 to traffic whose destination address is 10.2.0.8 so that the traffic can be sent to the intranet FTP server.

Configuration Roadmap

Configure NAT policy for Internet users to access the intranet FTP server using a public IP address.
On the GigabitEthernet 0/0/1 and GigabitEthernet 0/0/7, configure sticky load balancing and default gateway.

Make clear the incoming interface of the traffic that may have different forward and return paths based on the configured routes and then configure the sticky load balancing function.

Procedure

Assign IP addresses to interfaces, add the interfaces to security zones, and configure network connectivity.

# Assign an IP address to GigabitEthernet 0/0/1.

<FW> system-view
[FW] interface GigabitEthernet 0/0/1
[FW-GigabitEthernet 0/0/1] ip address 1.1.1.1 24
[FW-GigabitEthernet 0/0/1] quit

# Assign an IP address to GigabitEthernet 0/0/2.

[FW] interface GigabitEthernet 0/0/2
[FW-GigabitEthernet 0/0/2] ip address 10.2.0.1 24
[FW-GigabitEthernet 0/0/2] quit

# Assign an IP address to GigabitEthernet 0/0/7.

[FW] interface GigabitEthernet 0/0/7
[FW-GigabitEthernet 0/0/7] ip address 2.2.2.2 24
[FW-GigabitEthernet 0/0/7] quit

# Add GigabitEthernet 0/0/2 to the DMZ zone.

[FW] firewall zone dmz
[FW-zone-dmz] add interface GigabitEthernet 0/0/2
[FW-zone-dmz] quit

# Add GigabitEthernet 0/0/1 to the untrust1 zone.

[FW] firewall zone name untrust1
[FW-zone-untrust1] set priority 10
[FW-zone-untrust1] add interface GigabitEthernet 0/0/1
[FW-zone-untrust1] quit

# Add GigabitEthernet 0/0/7 to the untrust2 zone.

[FW] firewall zone name untrust2
[FW-zone-untrust2] set priority 20
[FW-zone-untrust2] add interface GigabitEthernet 0/0/7
[FW-zone-untrust2] quit

Configure a security policy for traffic between Internet users and intranet servers.

[FW] security-policy
[FW-policy-security] rule name policy1
[FW-policy-security-rule-policy1] source-zone untrust1
[FW-policy-security-rule-policy1] source-zone untrust2
[FW-policy-security-rule-policy1] destination-zone dmz
[FW-policy-security-rule-policy1] destination-address 10.2.0.0 24
[FW-policy-security-rule-policy1] action permit
[FW-policy-security-rule-policy1] quit
[FW-policy-security] quit

Configure a destination NAT address pool.

[FW] destination-nat address-group addressgroup1
[FW-dnat-address-group-addressgroup1] section 10.2.0.8 10.2.0.8
[FW-dnat-address-group-addressgroup1] quit

Configure a NAT policy.

[FW] nat-policy
[FW-policy-nat] rule name policy1
[FW-policy-nat-rule-policy1] destination-address 1.1.10.10 32
[FW-policy-nat-rule-policy1] source-zone untrust1
[FW-policy-nat-rule-policy1] source-zone untrust2
[FW-policy-nat-rule-policy1] service ftp
[FW-policy-nat-rule-policy1] action destination-nat static address-to-address address-group addressgroup1
[FW-policy-nat-rule-policy1] quit
[FW-policy-nat] quit

Configure black-hole routes destined to the destination address of traffic to prevent routing loops.
```
[FW] ip route-static 1.1.10.10 255.255.255.255 NULL0
```

Enable NAT ALG for FTP.

[FW] firewall interzone dmz untrust1
[FW-interzone-dmz-untrust1] detect ftp
[FW-interzone-dmz-untrust1] quit

Configure the sticky load balancing function and default gateway.

[FW] interface GigabitEthernet 0/0/1
[FW-GigabitEthernet 0/0/1] redirect-reverse next-hop 1.1.1.254
[FW-GigabitEthernet 0/0/1] gateway 1.1.1.254
[FW-GigabitEthernet 0/0/1] quit
[FW] interface GigabitEthernet 0/0/7
[FW-GigabitEthernet 0/0/7] redirect-reverse next-hop 2.2.2.254
[FW-GigabitEthernet 0/0/7] gateway 2.2.2.254
[FW-GigabitEthernet 0/0/7] quit

On the router, configure a static route.
Contact your ISP administrator to perform this step.

Configuration Scripts

Configuration script for the FW:

#
 sysname FW
#
 ip route-static 1.1.10.10 255.255.255.255 NULL0
#
interface GigabitEthernet0/0/1
 undo shutdown
 ip address 1.1.1.1 255.255.255.0
 redirect-reverse next-hop 1.1.1.254
 gateway 1.1.1.254
#
interface GigabitEthernet0/0/2
 undo shutdown
 ip address 10.2.0.1 255.255.255.0 
#
interface GigabitEthernet0/0/7
 undo shutdown
 ip address 2.2.2.2 255.255.255.0 
 redirect-reverse next-hop 2.2.2.254
 gateway 2.2.2.254
#
firewall zone dmz
 set priority 50
 add interface GigabitEthernet0/0/2
#
firewall zone name untrust1 id 4
 set priority 10
 add interface GigabitEthernet0/0/1
#
firewall zone name untrust2 id 5
 set priority 20
 add interface GigabitEthernet0/0/7
# 
firewall interzone dmz untrust1 
 detect ftp 
#
destination-nat address-group addressgroup1
 section 10.2.0.8 10.2.0.8
#
nat-policy
 rule name policy1
  source-zone untrust1
  source-zone untrust2
  destination-address 1.1.10.10 32
  service ftp
  action destination-nat static address-to-address address-group addressgroup1
#  
security-policy   
  rule name policy1
    source-zone untrust1 
    source-zone untrust2
    destination-zone dmz 
    destination-address 10.2.0.0 24 
    action permit 
# 
return