Added -n option.

options.h

@@ -0,0 +1,29 @@
+/*
+ * options.h:
+ *
+ */
+
+#ifndef __OPTIONS_H_ /* include guard */
+#define __OPTIONS_H_
+
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+typedef struct {
+    /* interface to listen on */
+    char *interface;
+
+    /* pcap filter code */
+    char *filtercode;
+
+    /* Cross network filter */
+    int netfilter;
+    struct in_addr netfilternet;
+    struct in_addr netfiltermask;
+    int dnsresolution;
+    int promiscuous;
+
+} options_t;
+
+#endif /* __OPTIONS_H_ */