diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 0000000..ee4c50d
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1,4 @@
+* text=auto
+*.c text=text
+*.h text=text
+Makefile text eol=cr
diff --git a/.gitignore b/.gitignore
index c6127b3..a3cf4dc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,9 @@
 # Prerequisites
 *.d
+.idea
+depend
+port-open
+port-close
 
 # Object files
 *.o
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..5c4e678
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,63 @@
+# Generic MinGW makefile (C source only)
+# Modify variables/macros to fit your program
+
+INSTALL_DIR=/usr/local
+SBIN_DIR=$(INSTALL_DIR)/sbin
+
+# make / make all | will compile your program.
+# make clean      | deletes all compiled object and executable files.
+# make depend     | rebuilds the dependancy list
+# make run        | compiles (if needed) and runs your program
+
+# Compiler command
+CC = gcc
+
+# Linker command
+LD = gcc
+
+# Flags to pass to the compiler - add "-g" to include debug information
+CFLAGS = -Wall
+
+# Flags to pass to the linker
+LDFLAGS =
+
+# Command used to delete files
+RM = rm
+
+# List your object files here
+OBJS = port-open.o
+
+# List your source files here
+SRCS = port-open.c
+
+# Define your compile target here.
+PROG = port-open
+
+# Compile everything.
+all: $(PROG)
+
+# Link the program
+$(PROG): $(OBJS)
+	$(LD) $(LDFLAGS) $(OBJS) -s -o $(PROG)
+
+# All .o files depend on their corresponding .c file
+%.o: %.c
+	$(CC) $(CFLAGS) -c $<
+
+install:
+	cp -a port-open $(SBIN_DIR)/
+	cd $(SBIN_DIR) && ln -fs port-open port-close
+
+clean:
+	$(RM) -f $(PROG)
+	$(RM) -f *.o port-close
+
+distclean: clean
+	$(RM) -f depend
+
+
+depend:
+	$(CC) $(CFLAGS) -MM $(SRCS) > depend
+
+
+include depend
diff --git a/README.md b/README.md
index 506c1bc..6fe2934 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,52 @@
 # knockd-tools
 Tools to use with Judd Vinet's knockd
+
+## ABOUT
+
+This set of tools to use with [Judd Vinet's knockd](https://zeroflux.org/projects/knock) port-knocking server/client.
+The same functionality can be accomplished with a small script, but port-close which will stay in ram for hours and
+maybe days uses very little ram.
+
+## INSTALL
+
+To install the tools in /usr/local/sbin run:
+
+    $ make
+    $ sudo make install
+
+If you want other directories, edit Makefile and change:
+
+    INSTALL_DIR=/usr/local
+    SBIN_DIR=$(INSTALL_DIR)/sbin
+
+Or simply copy port-open to whatever dir you want and make a sym or hard link port-close pointing to port-open
+
+## EXAMPLE
+
+First you need to create **iptables** rules:
+
+    iptables -N knock
+    iptables -I INPUT -j knock 
+
+For example configuration check `knockd-example.conf`
+
+## TEST
+
+To test your installation you can run:
+
+    iptables -N knock
+    port-open 8.8.8.8 80 20
+    watch iptables -xvnL knock
+
+You should see a rule accepting connections from 8.8.8.8 on port 80. After after 20 seconds the rule should disappear. 
+
+
+    Chain knock (1 references)
+        pkts      bytes target     prot opt in     out     source               destination
+           0        0 ACCEPT     tcp  --  *      *       8.8.8.8              0.0.0.0/0           tcp dpt:80
+
+
+## LINKS
+
+ * [Judd Vinet's knockd](https://zeroflux.org/projects/knock)
+
diff --git a/knockd-example.conf b/knockd-example.conf
new file mode 100644
index 0000000..e9db00e
--- /dev/null
+++ b/knockd-example.conf
@@ -0,0 +1,31 @@
+[options]
+  logfile = /var/log/knockd.log
+  Interface = eth1
+#  Interface = eth0
+
+
+[openSSH]
+	sequence    = 1,2,3,4
+	seq_timeout = 10
+	command     = /usr/local/sbin/port-open %IP% 22 18000
+	tcpflags    = syn
+
+[openSSH2d]
+	sequence    = 5,6,7,8
+	seq_timeout = 10
+# timeout = 3600*24*2
+	command     = /usr/local/sbin/port-open %IP% 22 172800
+	tcpflags    = syn
+
+[closeSSH]
+	sequence    = 4,3,2,1
+	seq_timeout = 5
+	command     = /usr/local/sbin/port-close %IP% 22
+	tcpflags    = syn
+
+[beep]
+        sequence    = 2000,3000,4000
+        seq_timeout = 10
+        command     = echo "beep" >> /tmp/beep.log
+        tcpflags    = syn
+
diff --git a/port-open.c b/port-open.c
new file mode 100644
index 0000000..8c82aca
--- /dev/null
+++ b/port-open.c
@@ -0,0 +1,206 @@
+/**
+ * Compile:
+ * gcc -s -o port-open port-open.c
+ * cp -a port-open /usr/local/sbin
+ * cd /usr/local/sbin
+ * ln -sf port-open port-close
+ *
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <libgen.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#define IPTABLES_OPEN_CMD "/sbin/iptables -A knock -s %s -p tcp --dport %d -j ACCEPT >/dev/null"
+#define IPTABLES_CLOSE_CMD "/sbin/iptables -D knock -s %s -p tcp --dport %d -j ACCEPT >/dev/null 2>&1"
+
+#define PROG_PORT_OPEN 1
+#define PROG_PORT_CLOSE 2
+
+char *name;
+char progPath[1026];
+bool hasDir = false;
+int program = 1;
+long timeout = 0;
+
+bool verifyIp(const char *ip);
+bool verifyPort(long port);
+
+void usageOpen(){
+  printf("Adds ACCEPT rule for a given IP and port using iptables. If timeout is grater than 0 starts port-close with the same parameters:\n");
+  printf("Usage:\n");
+  printf("       %s <ip> <port> [timeout=0]\n", name);
+}
+
+void usageClose(){
+  printf("Removes the iptables ACCEPT rule, previously added with port-open after timeout seconds.\n");
+  printf("Usage:\n");
+  printf("       %s <ip> <port> [timeout=0]\n", name);
+}
+
+void usage() {
+  switch(program){
+    case PROG_PORT_OPEN:
+      usageOpen();
+      break;
+    case PROG_PORT_CLOSE:
+      usageClose();
+      break;
+  }
+}
+
+int portOpen(int argc, char **argv){
+  long tmp;
+  char **endPtr = NULL;
+
+  if(argc < 3){
+    usageOpen();
+    return 1;
+  }
+
+  const char *ip = argv[1];
+  if(!verifyIp(ip))
+    return 1;
+
+  tmp = strtol(argv[2], endPtr, 10);
+  const int port = (int) tmp;
+  if(!verifyPort(port))
+    return 1;
+
+  if(argc > 3){
+    timeout=strtol(argv[3], endPtr, 10);
+  }
+
+  char *cmd = malloc(1500);
+  sprintf(cmd, IPTABLES_OPEN_CMD, ip, (int)port);
+//  printf("running cmd: %s\n", cmd);
+  system(cmd);
+
+  if(timeout > 0) {
+    sprintf(cmd, "%sport-close %s %d %d", progPath, ip, (int)port, (int)timeout);
+//    printf("port close cmd: %s\n", cmd);
+    system(cmd);
+  }
+  free(cmd);
+
+  return 0;
+}
+
+int portClose(int argc, char **argv){
+  long tmp;
+  char **endPtr = NULL;
+
+  //printf("%d\n", argc);
+  if(argc < 3){
+    usageClose();
+    return 1;
+  }
+
+  const char *ip = argv[1];
+  if(!verifyIp(ip))
+    return 1;
+
+  tmp = strtol(argv[2], endPtr, 10);
+  const int port = (int) tmp;
+  if(!verifyPort(port))
+    return 1;
+
+  if(argc > 3){
+    timeout=strtol(argv[3], endPtr, 10);
+  }
+
+  //printf("%d\n", timeout);
+  if(timeout > 0) {
+    // drop stdout and stderr
+    close(STDOUT_FILENO);
+    close(STDERR_FILENO);
+    if(fork() != 0) {
+      // parent
+      return 0;
+    }
+
+    sleep(timeout);
+  }
+  char *cmd = malloc(1500);
+  sprintf(cmd, IPTABLES_CLOSE_CMD, ip, port);
+//  printf("running cmd: %s\n", cmd);
+  system(cmd);
+  free(cmd);
+  return 0;
+}
+
+bool verifyIp(const char *ip){
+  if(strlen(ip)<7){
+    printf("IP should be least 7 characters\n");
+    usage();
+    return false;
+  }
+  if(strlen(ip)>15){
+    printf("IP should be max 15 characters\n");
+    usage();
+    return false;
+  }
+  return true;
+}
+
+bool verifyPort(long port) {
+  if(port<0) {
+    printf("port cannot be negative");
+    usage();
+    return false;
+  }
+  if(port>65535) {
+    printf("port must be less than 65535");
+    usage();
+    return false;
+  }
+  if(port==0) {
+    printf("Port must be grater than 0");
+    usage();
+    return false;
+  }
+  return true;
+}
+
+int main(int argc, char **argv){
+
+  if(argc<1){
+    printf("argc < 1 !!!\n");
+  }
+  name = basename(argv[0]);
+  if(strcmp(name, "port-open") == 0){
+    program = PROG_PORT_OPEN;
+  }else if(strcmp(name, "port-close") == 0) {
+    program = PROG_PORT_CLOSE;
+  }
+
+  char *dirTemp = dirname(argv[0]);
+  if (strlen(dirTemp) > 1024) {
+    printf("Can't work with paths longer than 1024 chars\n");
+    return 1;
+  }
+  if(strchr(argv[0], '/') == NULL) {
+    progPath[0] = 0;
+  }else {
+    strncpy(progPath, dirTemp, 1024);
+    int len = strlen(progPath);
+    progPath[len-1] = '/';
+    progPath[len] = 0;
+  }
+
+  switch(program){
+    case PROG_PORT_OPEN:
+      portOpen(argc, argv);
+      break;
+    case PROG_PORT_CLOSE:
+      portClose(argc, argv);
+      break;
+  }
+
+  return 0;
+}
+