19-10 | Cisco Systems ASA 5500 manual

Chapter 19 Managing the AIP SSM and CSC SSM

Managing the CSC SSM

•Incoming SMTP connections destined to inside mail servers.

In Figure 19-3, the adaptive security appliance should be configured to divert traffic to CSC SSM requests from clients on the inside network for HTTP, FTP, and POP3 connections to the outside network and incoming SMTP connections from outside hosts to the mail server on the DMZ network. HTTP requests from the inside network to the web server on the DMZ network should not be scanned.

Figure 19-3 Common Network Configuration for CSC SSM Scanning

Security

appliance

192.168.10.0

inside

outside	192.168.30.0	Internet

192.168.20.0

(dmz)

143800

Web server

Mail server

There are many ways you could configure the adaptive security appliance to identify the traffic that you want to scan. One approach is to define two service policies, one on the inside interface and the other on the outside interface, each with an access list that matches traffic to be scanned. The following access list could be used on the policy applied to the inside interface:

access-list csc_out permit tcp 192.168.10.0 255.255.255.0 any eq 21

access-list csc_out deny tcp 192.168.10.0 255.255.255.0 192.168.20.0 255.255.255.0 eq 80 access-list csc_out permit tcp 192.168.10.0 255.255.255.0 any eq 80

access-list csc_out permit tcp 192.168.10.0 255.255.255.0 any eq 110

As previously mentioned, policies applying the csc command to a specific interface are effective on both ingress and egress traffic, but by specifying 192.168.10.0 as the source network in the csc_out access list the policy applied to the inside interface matches only connections initiated by the hosts on the inside network. Notice also that the second ACE of the access list uses the deny keyword. This ACE does not mean the adaptive security appliance blocks traffic sent from the 192.168.10.0 network to TCP port 80 on the 192.168.20.0 network. It simply exempts the traffic from being matched by the policy map and thus prevents the adaptive security appliance from sending it to the CSC SSM.

You can use deny statements in an access list to exempt connections with trusted external hosts from being scanned. For example, to reduce the load on the CSC SSM, you might want to exempt HTTP traffic to a well known, trusted site. If the web server at such a site had the IP address 209.165.201.7, you could add the following ACE to the csc_out access list to exclude HTTP connections between the trusted external web server and inside hosts from being scanned by CSC SSM:

access-list csc_out deny tcp 192.168.10.0 255.255.255.0 209.165.201.7 255.255.255.255 eq 80

The second policy in this example, applied to the outside interface, could use the following access list:

access-list csc_in permit tcp any 192.168.20.0 255.255.255.0 eq 25

	Cisco Security Appliance Command Line Configuration Guide
19-10	OL-8629-01

ASA 5500 specifications

Cisco Systems ASA 5500 is a robust security appliance designed to provide advanced network security and protection against both internal and external threats. Ideal for organizations of various sizes, the ASA 5500 series offers a wide range of features that combine firewall capabilities with intrusion prevention, VPN support, and application control, among others.

One of the key features of the ASA 5500 is its stateful firewall technology. This allows the device to monitor active connections and enforce security policies based on the state of the traffic. By maintaining the context of network sessions, the firewall can make informed decisions on whether to allow or deny traffic based on established rules.

In addition to traditional firewall functionalities, the ASA 5500 series integrates advanced intrusion prevention capabilities. By analyzing traffic patterns and identifying known threats, the IPS functionality helps organizations defend against a variety of malicious activities, such as DDoS attacks, malware, and unauthorized access attempts. The ASA 5500 continuously updates its threat intelligence through Cisco's global threat database, enhancing its ability to detect emerging threats in real-time.

Virtual Private Network (VPN) support is another significant aspect of the ASA 5500 series. The device offers secure, encrypted connections for remote users and branch offices, ensuring safe access to corporate resources over the Internet. It supports both IPsec and SSL VPN protocols, allowing organizations to choose the best option for their specific needs. This capability is crucial for businesses that require a secure environment for remote work.

The ASA 5500 series also features extensive application control and visibility tools. These tools enable organizations to manage and control the applications running on their network, ensuring that only authorized applications can communicate through the firewall. This level of control helps to mitigate risks associated with unauthorized applications, which can lead to data breaches or reduced productivity.

Moreover, the ASA 5500 is designed with high availability and scalability in mind. Its clustering support ensures that multiple units can work together to provide redundancy and load balancing, enhancing both performance and reliability. This characteristic is especially important for organizations looking to maintain continuous operation during traffic spikes or hardware failures.

In summary, Cisco Systems ASA 5500 is an all-in-one security solution that combines stateful firewall protection, intrusion prevention, VPN capabilities, and application control. With its robust feature set and focus on security, it is well-suited for organizations seeking to protect their networks from an ever-evolving landscape of cyber threats. Whether for small businesses or large enterprises, the ASA 5500 provides the necessary tools to create a secure networking environment.