add the knocker application

knocker

@@ -0,0 +1,108 @@
+#!/usr/bin/env python2
+
+import argparse, ConfigParser, os, socket, subprocess
+
+class Knocker:
+    def __init__(self, host, target_port, openseq, closeseq):
+        self.host = host;
+        self.target_port = target_port;
+        self.openseq = openseq;
+        self.closeseq = closeseq;
+
+        self.skt = socket.socket(socket.AF_INET, socket.SOCK_STREAM);
+
+    def is_open(self):
+        return self.knock(self.target_port);
+
+    def open(self):
+        print self.openseq;
+        for port in self.openseq:
+            self.knock(port);
+
+    def close(self):
+        print self.closeseq;
+        for port in self.closeseq:
+            self.knock(port);
+
+    def knock(self, port):
+        try:
+            self.skt.connect( (self.host, port) );
+            self.skt.shutdown(2);
+            return True;
+        except:
+            return False;
+
+
+if __name__ == "__main__":
+    cfg = {
+            'host': 'localhost',
+            'port': 22,
+            'command': 'ssh localhost',
+            'openseq': [1234, 5678, 9123],
+            'closeseq': [2345, 6789, 1234]
+            };
+
+    # configure from config file
+    cp = ConfigParser.SafeConfigParser();
+    cp.read([os.path.expanduser("~/.knocker")]);
+
+    if cp.has_section('config'):
+        for op in cfg.keys():
+            if cp.has_option('config', op):
+                if op in ['host', 'command']:
+                    cfg[op] = cp.get('config', op);
+
+                elif op == 'port':
+                    cfg[op] = cp.getint('config', op);
+
+                elif op in ['openseq', 'closeseq']:
+                    _ = cp.get('config', op);
+                    _ = _.replace(' ', '');
+                    _ = _.split(',');
+                    cfg[op] = [ int(__) for __ in _ ];
+
+    # configure from command line
+    p = argparse.ArgumentParser(description="Port Knocker");
+
+    p.add_argument('-H', '--host', action='store', type=str, 
+            dest='host', default=cfg['host'], help="host");
+
+    p.add_argument('-p', '--target-port', action='store', type=int,
+            dest='port', default=cfg['port'], help="target port to open");
+
+    p.add_argument('-r', '--command', action='store', type=str,
+            dest='command', default=cfg['command'], help="command to run");
+
+    p.add_argument('-o', '--open-seq', action='store', type=int, nargs='+',
+            dest='openseq', default=cfg['openseq'], help="open sequence");
+
+    p.add_argument('-c', '--close-seq', action='store', type=int, nargs='+',
+            dest='closeseq', default=cfg['closeseq'], help="close sequence");
+
+    p.add_argument('-O', '--no-open', action='store_false', default=True,
+            dest='doopen', help="don't try to open the port");
+
+    p.add_argument('-C', '--no-close', action='store_false', default=True,
+            dest='doclose', help="don't try to close the port");
+
+    args = p.parse_args();
+
+    # start knocking
+    knocker = Knocker(args.host, args.port, args.openseq, args.closeseq);
+
+    if args.doopen and not knocker.is_open():
+        print "\033[92m  -> opening ports...",
+        knocker.open();
+        print "done\033[0m"
+
+    print "  \033[92m-> starting command...\033[0m"
+
+    # run command
+    subprocess.call(args.command, shell=True);
+
+    print "  \033[92m-> command done\033[0m"
+
+    if args.doclose:
+        print "  \033[92m-> closing ports...",
+        knocker.close();
+        print "done\033[0m"