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Manual Chapter: Setting Up IP Address Intelligence Blocking
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Setting Up IP Address Intelligence Blocking

Overview: Setting up IP address intelligence blocking

In Application Security Manager™, you can use IP address intelligence blocking in a security policy to block requests from IP addresses that have questionable reputations. IP addresses from which attacks or spam have originated are included in an IP intelligence database, along with the category describing the problem. The BIG-IP® system must connect to the IP intelligence database before you can use IP address intelligence blocking.

You can configure a security policy to log (alarm) or block requests from IP addresses of questionable reputation, and to perform different actions depending on the categories of problems. For example, you can block requests from IP addresses associated with Windows exploits and log requests from scanners.

You can create a whitelist of IP addresses that might be in the database, and allow them to access the web application regardless of their IP reputation. This is a way to ensure that traffic from known sources is not blocked because of IP address intelligence data.

You can also use iRules to instruct the system how to use IP address intelligence information.

Task summary

Downloading the IP address intelligence database

The requirements for using IP address intelligence are:
  • The system must have an IP Intelligence license.
  • The system must have an Internet connection either directly or through an HTTP proxy server.
  • The system must have DNS configured (go to System > Configuration > Device > DNS ).
Important: IP address intelligence is enabled by default if you have a license for it. You only need to enable it if it was previously disabled.
To enable IP address intelligence on the BIG-IP® system, you enable auto-update to download the IP intelligence database to the system.
  1. Log in to the command line for the BIG-IP® system.
  2. To determine whether IP intelligence auto-update is enabled, type the following command: tmsh list sys db iprep.autoupdate
    If the value of the iprep.autoupdate variable is disable, IP intelligence is not enabled. If it is enable, your task is complete. No further steps are necessary.
  3. If disabled, at the prompt, type tmsh modify sys db iprep.autoupdate value enable
    The system downloads the IP intelligence database and stores it in the binary file, /var/IpRep/F5IpRep.dat. It is updated every 5 minutes.
  4. If the BIG-IP system is behind a firewall, make sure that the BIG-IP system has external access to vector.brightcloud.com using port 443.
    That is the IP Intelligence server from which the system gets IP Intelligence information.
  5. Optional: If the BIG-IP system connects to the Internet using a forward proxy server, set these system database variables.
    1. Type tmsh modify sys db proxy.host value hostname to specify the host name of the proxy server.
    2. Type tmsh modify sys db proxy.port value port_number to specify the port number of the proxy server.
    3. Type tmsh modify sys db proxy.username value username to specify the user name to log in to the proxy server.
    4. Type tmsh modify sys db proxy.password value password to specify the password to log in to the proxy server.
The IP address intelligence feature remains enabled unless you disable it with the command tmsh modify sys db iprep.autoupdate value disable.
You can create iRules® to instruct the system how to handle traffic from IP addresses with questionable reputations, or use Application Security Manager™ to configure IP address intelligence blocking. You can configure IP intelligence for Advanced Firewall Manager by assigning IP intelligence policies to the global, route domain, or virtual server context.

Setting up IP address intelligence blocking

You can configure a security policy to log and block requests from source IP addresses that, according to an IP intelligence database, have a bad reputation and could cause a potential attack.
  1. On the Main tab, click Security > Application Security > IP Addresses > IP Address Intelligence .
    The IP Address Intelligence screen opens.
  2. In the Current edited policy list near the top of the screen, verify that the edited security policy is the one you want to work on.
  3. Select the IP Address Intelligence check box.
    The screen refreshes, and displays additional configuration options.
  4. For the IP Address Whitelist setting, specify any IP addresses you want to allow, even if they are found in the IP intelligence database.
    1. Type the IP Address and Subnet Mask of the address to consider safe.
    2. Click Add.
    The system updates the whitelist with the new IP addresses.
  5. In the IP Address Intelligence Categories area, select Alarm or Block, or both, for the categories of IP addresses you are interested in.
    • Select Alarm to cause the system to log the IP address intelligence data (IP address intelligence category and status) on the Requests screen whenever a request is from a source IP address in that category.
    • Select Block to stop requests sent from a source IP address that matches that category
    Tip: To select all categories at once, click the Alarm or Block column name check boxes.
  6. Click Save.
The system matches source IP addresses to those in the IP address intelligence database. When a match is found, the violation Access from malicious IP address occurs. The system determines what category of reputation the IP address has, then logs or blocks the IP address according to how the IP Address Intelligence categories are set.

Reviewing IP address intelligence statistics

After you set up IP intelligence blocking on the Application Security Manager™, you can review statistics concerning how many requests were received from IP addresses with questionable reputations. You can also view the requests from those IP addresses.
  1. On the Main tab, click Security > Reporting > Application .
    The Charts screen opens.
  2. In the Charts area, next to View by, click IP Address Intelligence.
    The chart shows details about IP addresses that were used to send the illegal requests, grouped according to their reputation in the IP intelligence database.
  3. Hover over the pie chart or look at the Details table below it to see the categories of IP addresses with questionable reputations.
  4. Under Chart Path on the left, click View Requests to see the requests from IP addresses in the IP intelligence database.
    The Requests list opens.
  5. Click any request to view details about the request.
    The screen expands to show more information about the request. IP address intelligence information is shown in the Source IP Address field in the request details. The details include the category of the malicious IP address and information about when the IP intelligence database was last updated.
  6. If you have set up remote logging, you can also review IP intelligence data on the remote logger.
Based on the statistics and IP address intelligence categories that the IP addresses fall into, you can adjust what happens (alarm or block) when the system receives requests from IP addresses in different categories.

Creating an iRule to log IP address intelligence information

Before you can create an iRule to log IP address intelligence information, your system must have IP address intelligence enabled.
You use iRules® to log IP address intelligence categories to the file /var/log/ltm. This is an example of the type of iRule you can write.
  1. On the Main tab, click Local Traffic > iRules .
    The iRule List screen opens, displaying any existing iRules.
  2. Click Create.
    The New iRule screen opens.
  3. In the Name field, type a name, such as my_irule.
    The full path name of the iRule cannot exceed 255 characters.
  4. In the Definition field, type the iRule using Tool Command Language (Tcl) syntax.
    For example, to log all IP addresses and any associated IP address intelligence categories, type the following iRule:
    when CLIENT_ACCEPTED {
                 log local0. "IP Address Intelligence for IP address [IP::client_addr]: 
                 [IP::reputation [IP::client_addr]]"
               }
    
    Tip: For complete and detailed information iRules syntax, see the F5 Networks DevCentral web site (http://devcentral.f5.com).
  5. Click Finished.
    The new iRule appears in the list of iRules on the system.
When traffic is received from an IP address with a questionable reputation and that is included in the IP intelligence database, the system prints the IP address intelligence information in the /var/log/ltm log.
For complete and detailed information about iRules syntax, see the F5 Networks DevCentral web site, http://devcentral.f5.com.

Creating an iRule to reject requests with questionable IP addresses

Before you can create an iRule to reject requests based on an IP address reputation, your system must have IP address intelligence enabled.
You can use iRules® to reject requests from IP addresses that have questionable reputations and are listed in the IP intelligence database. This is an example of the type of iRule you can write.
  1. On the Main tab, click Local Traffic > iRules .
    The iRule List screen opens, displaying any existing iRules.
  2. Click Create.
    The New iRule screen opens.
  3. In the Name field, type a name, such as my_irule.
    The full path name of the iRule cannot exceed 255 characters.
  4. In the Definition field, type the iRule using Tool Command Language (Tcl) syntax.
    For example, to reject requests from IP addresses listed in the IP intelligence database because they could be Windows Exploits or Web Attacks, type the following iRule:
    when HTTP_REQUEST { 
        set ip_reputation_categories [IP::reputation [IP::client_addr]]
        set is_reject 0
        if {($ip_reputation_categories contains "Windows Exploits")} {
           set is_reject 1
        } 
        if {($ip_reputation_categories contains "Web Attacks")} {
           set is_reject 1
        } 
        if {($is_reject)} {
            log local0. "Attempted access from malicious IP address [IP::client_addr]
            ($ip_reputation_categories), request was rejected"
            HTTP::respond 200 content 
            "<HTML><HEAD><TITLE>Rejected Request</TITLE>
            </HEAD><BODY>The request was rejected. <BR> 
            Attempted access from malicious IP address</BODY></HTML>"
        }
    }
    
    
    Tip: For complete and detailed information about iRules syntax, see the F5 Networks DevCentral web site (http://devcentral.f5.com).
  5. Click Finished.
    The new iRule appears in the list of iRules on the system.
When the system receives traffic from an IP address that is included in the IP intelligence database, the system prints the IP address intelligence information in the /var/log/ltm log.

IP address intelligence categories

Along with the IP address, the IP intelligence database stores the category that explains the reason that the IP address is considered untrustworthy.

Category Name Description
Additional IP addresses that are added from additional categories not more explicitly defined.
Application Denial of Service IP addresses involved in application DoS Attacks, or anomalous traffic detection.
Botnets IP addresses of computers that are infected with malicious software (Botnet Command and Control channels, and infected zombie machines) and are controlled as a group by a Bot master, and are now part of a botnet. Hackers can exploit botnets to send spam messages, launch various attacks, or cause target systems to behave in other unpredictable ways.
Cloud Provider Networks IP addresses and networks that are used by cloud providers.
Denial-of-Service IP addresses that have launched denial-of-service (DoS) attacks, distributed denial-of-service (DDoS) attacks, anomalous SYN flood attacks, or anomalous traffic detection. These attacks are usually requests for legitimate services, but occur at such a fast rate that targeted systems cannot respond quickly enough and become bogged down or unable to service legitimate clients.
Illegal Web Sites IP addresses that contain criminally obscene or potentially criminal internet copyright and intellectual property violations.
Infected Sources Active IP addresses that issue HTTP requests with a low reputation index score, or that are known malicious web sites offering or distributing malware, shell code, rootkits, worms, or viruses.
Phishing Proxies IP addresses that host phishing sites, and other kinds of fraud activities, such as ad click fraud or gaming fraud.
Proxy IP addresses that are associated with web proxies that shield the originator's IP address (such as proxy and anonymization services). This category also includes TOR anonymizer addresses.
Scanners IP addresses that are involved in reconnaissance, such as probes, host scan, domain scan, and password brute force, typically to identify vulnerabilities for later exploits.
Spam Sources IP addresses tunneling spam messages through proxy, anomalous SMTP activities and forum spam activities.
Web Attacks IP addresses involved in cross site scripting, iFrame injection, SQL injection, cross domain injection, or domain password brute force.
Windows Exploits Active IP addresses that have exercised various exploits against Windows resources by offering or distributing malware, shell code, rootkits, worms, or viruses using browsers, programs, downloaded files, scripts, or operating system vulnerabilities.
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