Fix type check, and add asserts submodule

.gitmodules

@@ -7,3 +7,6 @@
 [submodule "vendor/github.com/bitly/go-hostpool"]
 	path = vendor/github.com/bitly/go-hostpool
 	url = https://github.com/bitly/go-hostpool
+[submodule "vendor/github.com/bmizerany/assert"]
+	path = vendor/github.com/bmizerany/assert
+	url = https://github.com/bmizerany/assert

raw_socket_listener/listener.go

@@ -441,7 +441,7 @@ func (t *Listener) readPcap() {
 					}
 
 					// Invalid length
-					if ihl * 4 > ipLength {
+					if int(ihl * 4) > ipLength {
 						continue
 					}