Chapter 3 Information About NAT (ASA 8.3 and Later)

NAT for VPN

Figure 3-25shows a VPN client Telnetting to the ASA inside interface. When you use a management-access interface, and you configure identity NAT according to the “NAT and Remote Access VPN” or “NAT and Site-to-Site VPN” section, you must configure NAT with the route lookup option. Without route lookup, the ASA sends traffic out the interface specified in the NAT command, regardless of what the routing table says; in the below example, the egress interface is the inside interface. You do not want the ASA to send the management traffic out to the inside network; it will never return to the inside interface IP address. The route lookup option lets the ASA send the traffic directly to the inside interface IP address instead of to the inside network. For traffic from the VPN client to a host on the inside network, the route lookup option will still result in the correct egress interface (inside), so normal traffic flow is not affected. See the “Determining the Egress Interface” section on page 3-24for more information about the route lookup option.

Figure 3-25 VPN Management Access

2.ASA decrypts packet; src address is now local address

 

 

209.165.201.10

 

 

10.3.3.10

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3. Identity NAT between

 

inside &

 

 

 

 

 

VPN client NWs; route

-

lookup req’d

 

1. Telnet request to ASA inside ifc;

Src: 10.3.3.10

10.3.3.10

 

 

 

management-access config req’d

 

 

 

 

Dst: 10.1.1.1

 

 

10.1.1.1

 

 

 

Src: 209.165.201.10

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4.Telnet request to 10.1.1.1

 

 

 

 

 

 

 

 

 

Src: 10.3.3.10

 

 

 

ASA Inside IP:10.1.1.1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VPN Client

 

 

 

Inside

 

 

 

 

 

 

 

 

 

 

209.165.201.10

 

 

 

 

 

 

 

 

 

 

Internet

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Dst: 209.165.201.10

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

8. Telnet response to

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VPN Client

 

 

 

Dst: 10.3.3.10

Src: 10.1.1.1

 

 

10.1.1.1

 

 

 

 

 

 

 

 

Dst: 10.3.3.10

 

 

10.3.3.10

 

 

 

 

 

 

 

 

5. Telnet response

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

6. Ide

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

n

tity NAT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

to VPN Client

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Dst: 10.3.3.10

 

 

209.165.201.10

 

 

 

 

303461

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

7. ASA encrypts packet; dst address is now real address

See the following sample NAT configuration for the above network:

! Enable hairpin for non-split-tunneled VPN client traffic:

same-security-traffic permit intra-interface

! Enable management access on inside ifc:

management-access inside

! Identify local VPN network, & perform object interface PAT when going to Internet:

object network vpn_local

subnet 10.3.3.0 255.255.255.0

nat (outside,outside) dynamic interface

!Identify inside network, & perform object interface PAT when going to Internet: object network inside_nw

subnet 10.1.1.0 255.255.255.0

nat (inside,outside) dynamic interface

Cisco ASA Series Firewall ASDM Configuration Guide

3-30

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Cisco Systems ASA 5555-X, ASA 5505, ASA 5545-X, ASA 5585-X, ASA 5580, ASA Services Module manual VPN Management Access
Page 79 Page 81

ASA Services Module, ASA 5555-X, ASA 5545-X, ASA 5585-X, ASA 5580 specifications

Cisco Systems has long been a leader in the field of network security, and its Adaptive Security Appliance (ASA) series is a testament to this expertise. Within the ASA lineup, models such as the ASA 5505, ASA 5580, ASA 5585-X, ASA 5545-X, and ASA 5555-X stand out for their unique features, capabilities, and technological advancements.

The Cisco ASA 5505 is designed for small businesses or branch offices. It provides essential security features such as firewall protection, flexible VPN capabilities, and intrusion prevention. The ASA 5505 supports a user-friendly interface, allowing for straightforward management. Its built-in threat detection and prevention tools provide a layered defense, and with scalability in mind, it can accommodate various expansion options as organizational needs grow.

Moving up the line, the ASA 5580 delivers greater throughput and advanced security features. This model is suited for medium to large enterprises that require robust protection against increasingly sophisticated threats. Its multi-core architecture allows it to manage high volumes of traffic seamlessly while maintaining excellent performance levels. The ASA 5580 also supports application-layer security and customizable access policies, making it highly adaptable to diverse security environments.

The ASA 5585-X further enhances Cisco's security offerings with advanced malware protection and extensive security intelligence capabilities. It incorporates next-generation firewall features, including context-aware security, and supports advanced threat detection technologies. This model is ideal for large enterprises or data centers that prioritize security while ensuring uninterrupted network performance and availability.

For enterprises requiring a balance of performance and security, the ASA 5545-X presents a compelling option. This model features scalable performance metrics, high availability, and integrated advanced threat protection. Coupled with advanced endpoint protection and detailed monitoring capabilities, the ASA 5545-X enables organizations to manage their security posture effectively.

Lastly, the ASA 5555-X blends cutting-edge technologies with strong security infrastructures. It boasts high throughput and the ability to execute deep packet inspections. Its sophisticated architecture supports threat intelligence feeds that provide real-time security updates, making it a powerful tool against modern threats.

Each of these Cisco ASA models brings specific advantages to varied environments. Their integrative capabilities enable businesses to enhance their security postures while benefiting from seamless scalability and management. As cybersecurity threats evolve, these advanced appliances play a vital role in protecting valuable digital assets.
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