Symantec recommends using the bundled version of Npcap, currently 1.10, with Symantec DLP Network Monitor.
Packet Capture in Windows requires software to integrate with Network Interface Cards (NICs).
DLP\Symantec_DLP_15.8_Platform_Win-IN_15.8.00000.19012\New_Installs\Third_Party\npcap-1.10-oem.exe
Symantec previously recommended using the newest version of WinPcap 4.1.2 with Symantec Data Loss Prevention.
Symantec_DLP_15.7_Platform_Win-IN_15.7.0.18016\DLP\15.7\Third_Party\WinPcap\WinPcap_4_1_3.exe
Note: Neither Npcap, nor WinPcap, are required if you are using Endace or Napatech NICs to capture traffic.