PacketTunnelProvider: Unable to connect to Unix Domain Sockets

Hi,

I am modifying my legacy remote access vpn application to make use of NetworkExtension framework.

In order to achieve this I need my PacketTunnelProvider to exchange a few messages with a process running on the machine.

Note that this is a separate process, not the containing application.

I want this communication to happen over unix domain sockets. I have right entitlements in place for my extension as well as the containing application.

  </array>
  <key>com.apple.security.app-sandbox</key>
  <true/>
  <key>com.apple.security.files.user-selected.read-write</key>
  <true/>
  <key>com.apple.security.network.client</key>
  <true/>
  <key>com.apple.security.network.server</key>
  <true/>
  <key>keychain-access-groups</key>
  <array>

When my PacketTunnelProvider tries to connect and send data over the unix domain socket, I see following errors on console:

default 16:32:16.399061+0530 PacketTunnel Connect error: Operation not permitted
default 16:32:16.399117+0530 PacketTunnel Write error: Socket is not connected
error 16:32:16.439901+0530 sandboxd Sandbox: PacketTunnel(975) deny(1) network-outbound /Users/sumsum/socktes/msgsock
Violation:       deny(1) network-outbound /Users/sumsum/socktes/msgsock

Can someone please let me know if I am missing something here? Is there any issue in app sandboxing that I am hitting?
Thank You.