diff --git a/core/Makefile b/core/Makefile
index 231b6c9..a9548c1 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -2,7 +2,7 @@ CC = gcc
 CFLAGS = -O0 -I../include -I../../c-libp2p/include -I../../c-protobuf -Wall
 LFLAGS = 
 DEPS = builder.h ipfs_node.h
-OBJS = builder.o daemon.o null.o
+OBJS = builder.o daemon.o null.o ping.o
 
 %.o: %.c $(DEPS)
 	$(CC) -c -o $@ $< $(CFLAGS)
diff --git a/core/null.c b/core/null.c
index 6aa91cf..dcf1347 100644
--- a/core/null.c
+++ b/core/null.c
@@ -1,20 +1,39 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdint.h>
+#include <string.h>
 #include <unistd.h>
 #include <pthread.h>
 #include "libp2p/net/p2pnet.h"
 #include "ipfs/core/daemon.h"
 
+#define BUF_SIZE 4096
+
 void *ipfs_null_connection (void *ptr)
 {
     struct null_connection_params *connection_param;
+    char b[BUF_SIZE];
+    int len;
 
     connection_param = (struct null_connection_params*) ptr;
 
     // TODO: multistream + secio + message.
     fprintf(stderr, "Connection %d, count %d\n", connection_param->socket, *(connection_param->count));
 
+    for(;;) {
+        len = socket_read(connection_param->socket, b, sizeof(b)-1, 0);
+        if (len > 0) {
+            while (b[len-1] == '\r' || b[len-1] == '\n') len--;
+            b[len] = '\0';
+            fprintf(stderr, "Recv: '%s'\n", b);
+            if (strcmp (b, "ping") == 0) {
+                socket_write(connection_param->socket, "pong", 4, 0);
+            }
+        } else if(len < 0) {
+            break;
+        }
+    }
+
     close (connection_param->socket); // close socket.
     (*(connection_param->count))--; // update counter.
     free (connection_param);
diff --git a/core/ping.c b/core/ping.c
new file mode 100644
index 0000000..b915e27
--- /dev/null
+++ b/core/ping.c
@@ -0,0 +1,63 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/time.h>
+#include <arpa/inet.h>
+#include "libp2p/net/p2pnet.h"
+
+#define BUF_SIZE 4096
+
+int ipfs_ping (int argc, char **argv)
+{
+    int socketfd, i, count=10, tcount = 0;
+    uint32_t ipv4;
+    uint16_t port;
+    char b[BUF_SIZE];
+    size_t len;
+    struct timeval time;
+    long cur_time, old_time;
+    double ms, total = 0;
+
+    if (inet_pton (AF_INET, argv[2], &ipv4) == 0) {
+        fprintf(stderr, "Unable to use '%s' as an IP address.\n", argv[1]);
+        return 1;
+    }
+
+    if ((port = atoi(argv[3])) == 0) {
+        fprintf(stderr, "Unable to use '%s' port.\n", argv[2]);
+        return 1;
+    }
+
+    if ((socketfd = socket_tcp4()) <= 0) {
+        perror("can't create socket");
+        return 1;
+    }
+
+    if (socket_connect4(socketfd, ipv4, port) < 0) {
+        perror("fail to connect");
+        return 1;
+    }
+
+    fprintf(stderr, "PING %s.\n", argv[2]);
+
+    for (i=0 ; i < count ; i++) {
+        if (gettimeofday (&time, 0)) return -1;
+        old_time = 1000000 * time.tv_sec + time.tv_usec;
+
+        socket_write(socketfd, "ping", 4, 0);
+        len = socket_read(socketfd, b, sizeof(b), 0);
+
+        if (len == 4 && memcmp(b, "pong", 4) == 0) {
+            if (gettimeofday (&time, 0)) return -1;
+            cur_time = 1000000 * time.tv_sec + time.tv_usec;
+            ms = (cur_time - old_time) / 1000.0;
+            total += ms; tcount++;
+            fprintf(stderr, "Pong received: time=%.2f ms\n", ms);
+        }
+        sleep (1);
+    }
+    fprintf(stderr, "Average latency: %.2fms\n", total / tcount);
+
+    return 0;
+}
diff --git a/include/ipfs/core/daemon.h b/include/ipfs/core/daemon.h
index e6b7717..b471865 100644
--- a/include/ipfs/core/daemon.h
+++ b/include/ipfs/core/daemon.h
@@ -18,4 +18,5 @@
     void *ipfs_null_connection (void *ptr);
     void *ipfs_null_listen (void *ptr);
     int ipfs_daemon (int argc, char **argv);
+    int ipfs_ping (int argc, char **argv);
 #endif // DAEMON_H
diff --git a/main/Makefile b/main/Makefile
index da43dfe..e5c1107 100644
--- a/main/Makefile
+++ b/main/Makefile
@@ -7,7 +7,7 @@ OBJS = main.o \
 	../cid/cid.o \
 	../cmd/ipfs/init.o \
 	../commands/argument.o ../commands/command_option.o ../commands/command.o ../commands/cli/parse.o \
-	../core/builder.o ../core/daemon.o ../core/null.o \
+	../core/builder.o ../core/daemon.o ../core/null.o ../core/ping.o \
 	../datastore/ds_helper.o \
 	../datastore/key.o \
 	../dnslink/dnslink.o \
diff --git a/main/main.c b/main/main.c
index 780f81f..24e32b0 100644
--- a/main/main.c
+++ b/main/main.c
@@ -5,6 +5,7 @@
 #include "ipfs/importer/importer.h"
 #include "ipfs/importer/exporter.h"
 #include "ipfs/dnslink/dnslink.h"
+#include "ipfs/core/daemon.h"
 
 #ifdef __MINGW32__
     void bzero(void *s, size_t n)
@@ -55,6 +56,7 @@ void strip_quotes(int argc, char** argv) {
 #define DNS 4
 #define CAT 5
 #define DAEMON 6
+#define PING 7
 
 /***
  * Basic parsing of command line arguments to figure out where the user wants to go
@@ -82,6 +84,9 @@ int parse_arguments(int argc, char** argv) {
 	if (strcmp("daemon", argv[1]) == 0) {
 		return DAEMON;
 	}
+	if (strcmp("ping", argv[1]) == 0) {
+		return PING;
+	}
 	return -1;
 }
 
@@ -110,5 +115,8 @@ int main(int argc, char** argv) {
 	case (DAEMON):
 		ipfs_daemon(argc, argv);
 		break;
+	case (PING):
+		ipfs_ping(argc, argv);
+		break;
 	}
 }