Test fix for rapid7#4305

Author: jhart-r7

lib/msf/core/exploit/capture.rb

@@ -309,7 +309,11 @@ def probe_gateway(addr)
         secret   = "#{preamble}#{Rex::Text.rand_text(rand(0xff)+1)}"
 
         begin
-          UDPSocket.open.send(secret, 0, dst_host, dst_port)
+          UDPSocket.open do |sock|
+            sock.setsockopt(::Socket::IPPROTO_IP, ::Socket::IP_TTL, 1)
+            sock.send(secret, 0, dst_host, dst_port)
+          end
+          #UDPSocket.open.send(secret, 0, dst_host, dst_port)
         rescue Errno::ENETUNREACH
           # This happens on networks with no gatway. We'll need to use a
           # fake source hardware address.