CLI: Example for Configuring Intranet Users to Access the Public Addresses of Intranet Servers

This section provides an example for configuring intranet users to access the public IP addresses of intranet servers.

Networking Requirements

An enterprise has deployed a FW as a security gateway on the intranet border. NAT Server is configured on the FW for the intranet web and File Transfer Protocol (FTP) servers to provide services for Internet users. PC D on the same network segment and security zone with the two servers. Source NAT is configured on the FW so that PC D can use a public address to access the two intranet servers.

The enterprise applies for two public IP addresses:

1.1.1.10 used by intranet servers.
1.1.1.11 into which PC D's private address is translated.

Figure 1 illustrates the networking for a source NAT policy in outbound interface mode. The router is an access gateway on the ISP network.

Figure 1 Networking diagram for NAT Server and source NAT

Data Planning

Item		Data	Description
GigabitEthernet 0/0/1		IP address: 1.1.1.1/24 Security zone: Untrust	1.1.1.1/24 is a public address provided by the ISP.
GigabitEthernet 0/0/2		IP address: 10.2.0.1/24 Security zone: DMZ	Intranet servers use 10.2.0.1 as the default gateway address.
NAT Server		Name: policy_web Public IP address: 1.1.1.10 Private IP address: 10.2.0.7 Public port: 8080 Private port: 80	When Internet users send traffic to 1.1.1.10 through port 8080, the FW can forward the traffic to the web server based on this mapping entry. On the web server, the private address is 10.2.0.7, and the private port number is 80.
NAT Server		Name: policy_ftp Public IP address: 1.1.1.10 Private IP address: 10.2.0.8 Public port: 21 Private port: 21	When Internet users send traffic to 1.1.1.10 through port 21, the FW can forward the traffic to the FTP server based on this mapping entry. On the FTP server, the private address is 10.2.0.8, and the private port number is 21.
Source NAT policy		Name: policy_nat1 Private address that can access the Internet: 10.2.0.6 Address in a NAT address pool: 1.1.1.11	-
Routing information	Default route	Destination address: 0.0.0.0 Next hop address: 1.1.1.254	Configure a default route on the FW to direct intranet traffic to the ISP network.

Configuration Roadmap

The configuration roadmap is as follows:

Assign IP addresses to interfaces, add the interfaces to security zones, and configure network connectivity.
Configure a security policy for traffic between intranet users and intranet servers.
Configure NAT Server. Configure two server mapping entries, one for the web server and the other for the FTP server.
Configure a source NAT policy to allow PC D to access the intranet servers based on the servers' public address.
Configure a default route on the FW to direct intranet traffic to the ISP router.
Configure static routes destined for public addresses of intranet servers on the router.

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

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

[FW] firewall zone untrust
[FW-zone-untrust] add interface GigabitEthernet 0/0/1
[FW-zone-untrust] 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

Configure a security policy.

[FW] security-policy
[FW-policy-security] rule name policy1
[FW-policy-security-rule-policy1] source-zone dmz untrust
[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 NAT address pool.

[FW] nat address-group addressgroup1
[FW-address-group-addressgroup1] mode pat
[FW-address-group-addressgroup1] section 0 1.1.1.11 1.1.1.11
[FW-address-group-addressgroup1] route enable
[FW-address-group-addressgroup1] quit

Configure a source NAT policy.

[FW] nat-policy
[FW-policy-nat] rule name policy_nat1
[FW-policy-nat-rule-policy_nat1] source-zone dmz
[FW-policy-nat-rule-policy_nat1] destination-zone dmz
[FW-policy-nat-rule-policy_nat1] source-address 10.2.0.6 32
[FW-policy-nat-rule-policy_nat1] action source-nat address-group addressgroup1
[FW-policy-nat-rule-policy_nat1] quit
[FW-policy-nat] quit

Configure NAT Server. Configure two server mapping entries, one for the web server and the other for the FTP server.

[FW] nat server policy_web protocol tcp global 1.1.1.10 8080 inside 10.2.0.7 www unr-route
[FW] nat server policy_ftp protocol tcp global 1.1.1.10 ftp inside 10.2.0.8 ftp unr-route

Enable NAT ALG for FTP.

[FW] firewall zone dmz
[FW-zone-dmz] detect ftp
[FW-zone-dmz] quit
[FW] firewall interzone dmz untrust
[FW-interzone-dmz-untrust] detect ftp
[FW-interzone-dmz-untrust] quit

Configure a default route to direct intranet traffic to the ISP router.
```
[FW] ip route-static 0.0.0.0 0.0.0.0 1.1.1.254
```
Configure a blackhole route to prevent routing loops between the FW and router.
```
[FW] ip route-static 1.1.1.10 32 NULL 0
```
On the router, configure a static route, in which the destination address is 1.1.1.10 and the next-hop address is 1.1.1.1. The router directs traffic destined for 1.1.1.10 to the FW based on the static route so that the FW can forward the traffic to the intranet server.
Contact your ISP administrator to perform this step.

Configuration Scripts

Configuration script for the FW:

#
 sysname FW
#
 nat server policy_web protocol tcp global 1.1.1.10 8080 inside 10.2.0.7 www unr-route
 nat server policy_ftp protocol tcp global 1.1.1.10 ftp inside 10.2.0.8 ftp unr-route

#
interface GigabitEthernet0/0/1
 undo shutdown
 ip address 1.1.1.1 255.255.255.0 
#
interface GigabitEthernet0/0/2
 undo shutdown
 ip address 10.2.0.1 255.255.255.0 
#
firewall zone untrust
 set priority 5
 add interface GigabitEthernet0/0/1
#
firewall zone dmz
 set priority 50
 add interface GigabitEthernet0/0/2
 detect ftp
# 
firewall interzone dmz untrust 
 detect ftp 
#
 ip route-static 0.0.0.0 0.0.0.0 1.1.1.254 
# 
nat address-group addressgroup1 0
 mode pat
 route enable
 section 0 1.1.1.11 1.1.1.11 
#  
security-policy   
  rule name policy1  
    source-zone dmz
    source-zone untrust 
    destination-zone dmz 
    destination-address 10.2.0.0 24 
    action permit 
#  
nat-policy  
  rule name policy_nat1 
    source-zone dmz 
    destination-zone dmz  
    source-address 10.2.0.6 32
    action source-nat address-group addressgroup1  
# 
return