diff --git a/main.cpp b/main.cpp
index 6743d76..133abb9 100755
--- a/main.cpp
+++ b/main.cpp
@@ -668,8 +668,10 @@ void async_cb(struct ev_loop *loop, struct ev_async *watcher, int revents)
 		memcpy(pcap_header_buf,p,pcap_link_header_len);
 
 		log_bare(log_info,"link level header captured:\n");
+		unsigned char *tmp=(unsigned char*)pcap_header_buf;
 		for(int i=0;i<pcap_link_header_len;i++)
-		log_bare(log_info,"<%x>",(u32_t)(unsigned char)pcap_header_buf[i]);
+		log_bare(log_info,"<%x>",(u32_t)tmp[i]);
+
 		log_bare(log_info,"\n");
 		return ;
 	}
@@ -787,7 +789,7 @@ int client_event_loop()
 	{
 		mylog(log_info,"--dev have not been set, trying to detect automatically, avaliable deives:\n");
 
-		mylog(log_info,"avaliable deives(and ip address):\n");
+		mylog(log_info,"avaliable deives(device name: ip address ; description):\n");
 
 		char errbuf[PCAP_ERRBUF_SIZE];
 
@@ -816,7 +818,12 @@ int client_event_loop()
 					}
 				}
 			}
-			if(cnt==0) log_bare(log_info," (no ip found)");
+			if(cnt==0) log_bare(log_info," [no ip found]");
+			if(d->description==0)
+			{
+				log_bare(log_info,"; (null)");
+			}
+			log_bare(log_info,"; %s", d->description);
 			log_bare(log_info,"\n");
 		}
 
diff --git a/pcap_wrapper.cpp b/pcap_wrapper.cpp
index f4ccee5..3b7c005 100644
--- a/pcap_wrapper.cpp
+++ b/pcap_wrapper.cpp
@@ -1,7 +1,7 @@
 #include <windows.h>
 #include <pcap_wrapper.h>
 #include <assert.h>
-
+#include <stdio.h>
 int	(*pcap_loop )(pcap_t *, int, pcap_handler, u_char *);
 
 pcap_t* (*pcap_create)(const char *, char *);
@@ -43,6 +43,11 @@ struct init_pcap_t
 int init_pcap()
 {
 	HMODULE wpcap=LoadLibrary("wpcap.dll");
+	if(wpcap==0)
+	{
+		printf("cant not open wpcap.dll, make sure winpcap/npcap is installed\n");
+		exit(-1);
+	}
 	assert(wpcap!=0);
 
 	pcap_loop = (__typeof__(pcap_loop))GetProcAddress(wpcap, "pcap_loop");