Configure DNS Sinkholing for a List of Custom Domains
To enable DNS Sinkholing for a custom list of domains, you must create an External Dynamic List that includes the domains, enable the sinkhole action in an Anti-Spyware profile and attach the profile to a security policy rule. When a client attempts to access a malicious domain in the list, the firewall forges the destination IP address in the packet to the default Palo Alto Networks server or to a user-defined IP address for sinkholing.
For each custom domain included in the external dynamic list, the firewall generates DNS-based spyware signatures. The signature is named Custom Malicious DNS Query <domain name>, and is of type spyware with medium severity; each signature is a 24-byte hash of the domain name.
Each firewall model supports a maximum of 50,000 domain names total in one or more external dynamic lists but no maximum limit is enforced for any one list.
- Enable DNS sinkholing for the custom list of domains
in an external dynamic list.
- Select ObjectsSecurity ProfilesAnti-Spyware.
- Modify an existing profile, or select one of the existing default profiles and clone it.
- Name the profile and select the DNS Signatures tab.
- Click Add and select External
Dynamic Lists in the drop-down.If you have already created an external dynamic list of type: Domain List, you can select it from here. The drop-down does not display external dynamic lists of type URL or IP Address that you may have created.
- Configure the external dynamic list from the Anti-Spyware profile (see Configure the Firewall to Access an External Dynamic List). The Type is preset to Domain List.
- (Optional) In the Packet Capture drop-down, select single-packet to capture the first packet of the session or extended-capture to set between 1-50 packets. You can then use the packet captures for further analysis.
- Verify the sinkholing settings on
the Anti-Spyware profile.
- On the DNS Signatures tab, verify that the Actionon DNS Queries is sinkhole.
- In the
Sinkhole section, verify that Sinkhole is
enabled. For your convenience, the default Sinkhole IP address is
set to access a Palo Alto Networks server. Palo Alto Networks can
automatically refresh this IP address through content updates.If you want to modify the Sinkhole IPv4 or Sinkhole IPv6 address to a local server on your network or to a loopback address, see Configure the Sinkhole IP Address to a Local Server on Your Network.
- Click OK to save the Anti-Spyware profile.
- Attach the Anti-Spyware profile to a Security policy
- Select PoliciesSecurity and select a security policy rule.
- On the Actions tab, select the Log at Session Start check box to enable logging.
- In the Profile Setting section, click the Profile Type drop-down to view all Profiles. From the Anti-Spyware drop-down and select the new profile.
- Click OK to save the policy rule.
- Test that the policy action is enforced.
- View External Dynamic List Entries that belong to the domain list, and access a domain from the list.
- To monitor the activity on the firewall:
- Select ACC and add a URL Domain as a global filter to view the Threat Activity and Blocked Activity for the domain you accessed.
- Select MonitorLogsThreat and filter by (action eq sinkhole) to view logs on sinkholed domains.
- Verify whether entries in the external dynamic list are
ignored or skipped.Use the following CLI command on the firewall to review the details about the list.
request system external-list show type domain name<list_name>For example:
request system external-list show type domain name My_List_of_Domains_2015 vsys1/EBLDomain: Next update at : Thu May 21 10:15:39 2015 Source : https://188.8.131.52/My_List_of_Domains_2015 Referenced : Yes Valid : Yes Number of entries : 3 domains:www.example.com baddomain.com qqq.abcedfg.com
- (Optional) Retrieve the external dynamic list
on-demand.To force the firewall to retrieve the updated list on-demand instead of at the next refresh interval (the Repeat frequency you defined for the external dynamic list), use the following CLI command:
request system external-list refresh type domain name <list_name>
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