Improved DHCP Traffic Visibility for IoT Security

IoT Security relies on IP address-to-MAC address bindings to ascribe observed network behaviors to IoT devices and uniquely track them. IoT Security typically uses DHCP traffic collected by next-generation firewalls to learn IP address-to-MAC address bindings and track IP address changes. However, when it’s not possible to position a firewall in the DHCP data path, you can use this method to ingest DHCP server logs and expand DHCP traffic visibility.

In areas of the network where it’s difficult to route DHCP traffic to or through a firewall, configure DHCP servers to send their server logs as syslog messages to the firewall. The firewall then forwards the messages as Enhanced Application Logs (EALs) with a subtype of dhcp-syslog through the logging service to IoT Security. IoT Security parses them to learn the IP address-to-MAC address bindings and then adds newly learned devices to its inventory.

• Prerequisites

  • A DHCP server with syslog capabilities configured to send messages to a syslog server running on a next-generation firewall
  • A next-generation firewall running PAN-OS^® 11.0 or later with an active IoT Security subscription
• Set up the Next-generation Firewall

  Set up your next-generation firewall to receive syslog messages from one or more DHCP servers. The firewall will automatically forward the syslog messages it receives as EALs to the logging service, which streams them to IoT Security to parse and analyze.

  1. Add a DHCP server to the next-generation firewall.
     Log in to your next-generation firewall, select DeviceIoT Security+ Add, configure the following, and then click OK:
     Name: Enter a name for the DHCP server. It can be up to 32 characters, including spaces.
     Description: Enter a note about the DHCP server for future reference. It can be up to 256 characters, including spaces.
     Enabled: Select to enable the firewall to listen for connections from the DHCP server and process them when they come.
     IP Address: Enter the IP address from which the DHCP server will connect to the firewall. The address can be in IPv4 or IPv6 format. An FQDN is not allowed.
     Protocol: Select TCP, UDP, or SSL. When making your choice, consider what’s important for the connection between the DHCP server and firewall. TCP provides transmission reliability but not security. UDP provides low processing overhead and faster speeds but lacks reliability and security. SSL provides reliability and security but incurs more overhead.
     The firewall listens for DHCP server connections using TCP and UDP on port 10514 and connections using SSL on port 16514.

  2. Repeat the previous step to add more DHCP servers.
     Add more DHCP servers to expand visibility of DHCP traffic throughout your network as needed. All next-generation firewalls support a maximum of 100 DHCP servers per firewall.
• Set up DHCP Servers for Syslog

  Configure your DHCP servers to send syslog messages of their server logs to the management interface on the next-generation firewall. Make sure to configure the DHCP servers to use the same protocol configured for them on the firewall: TCP, UDP, or SSL. You can use DHCP servers such as Windows, Linux, Cisco, or Infoblox for example. See your product documentation for specific DHCP server configuration instructions.
• Check DHCP Server Connection Status

  1. To see all the configured DHCP servers, select DeviceIoT Security.
     A green circle next to a DHCP server name means it was configured in Panorama and is read-only when viewed in the web interface of the local next-generation firewall.
     When a DHCP server using TCP or SSL is currently connected to the firewall, “Connected” appears in the Status column. “Connected” also appears in this column if a DHCP server using UDP has been connected within the past two hours. At all other times, the Status column is empty, indicating that the server isn’t currently connected to the firewall.
  2. Use the following CLI commands to check DHCP server settings, the status of their connections, and the data they’re providing to IoT Security.

     show iot dhcp-server status { all | server <server-name> }	Entering all shows a table with all DHCP servers configured and enabled on the firewall, the port numbers on which they connect, and their current connection status. Entering server <server-name> shows detailed information about a specific DHCP server and its recent activity.
     show iot eal dhcp-syslog-eal	This command shows information related to EALs carrying DHCP server syslog messages.