improve default ipc file locations

When transport is IPC, the default location for the IPC files
should be in the security dir.  This ensures that is the case
for both the `ipython kernel` and `ipython notebook` cases.
It already made sense in `ipython [qt]console`.

IPython/zmq/kernelapp.py

@@ -62,6 +62,7 b' kernel_aliases.update({'
     'stdin' : 'KernelApp.stdin_port',
     'f' : 'KernelApp.connection_file',
     'parent': 'KernelApp.parent',
+    'transport': 'KernelApp.transport',
 })
 if sys.platform.startswith('win'):
     kernel_aliases['interrupt'] = 'KernelApp.interrupt'
@@ -98,7 +99,6 b' class KernelApp(BaseIPythonApplication):'
     heartbeat = Instance(Heartbeat)
     session = Instance('IPython.zmq.session.Session')
     ports = Dict()
-    _full_connection_file = Unicode()
     
     # inherit config file name from parent:
     parent_appname = Unicode(config=True)
@@ -112,8 +112,16 b' class KernelApp(BaseIPythonApplication):'
         
     # connection info:
     transport = CaselessStrEnum(['tcp', 'ipc'], default_value='tcp', config=True)
-    ip = Unicode(LOCALHOST, config=True,
+    ip = Unicode(config=True,
         help="Set the IP or interface on which the kernel will listen.")
+    def _ip_default(self):
+        if self.transport == 'ipc':
+            if self.connection_file:
+                return os.path.splitext(self.abs_connection_file)[0] + '-ipc'
+            else:
+                return 'kernel-ipc'
+        else:
+            return LOCALHOST
     hb_port = Integer(0, config=True, help="set the heartbeat port [default: random]")
     shell_port = Integer(0, config=True, help="set the shell (ROUTER) port [default: random]")
     iopub_port = Integer(0, config=True, help="set the iopub (PUB) port [default: random]")
@@ -122,9 +130,16 b' class KernelApp(BaseIPythonApplication):'
     help="""JSON file in which to store connection info [default: kernel-<pid>.json]
     
     This file will contain the IP, ports, and authentication key needed to connect
-    clients to this kernel. By default, this file will be created in the security-dir
+    clients to this kernel. By default, this file will be created in the security dir
     of the current profile, but can be specified by absolute path.
     """)
+    @property
+    def abs_connection_file(self):
+        if os.path.basename(self.connection_file) == self.connection_file:
+            return os.path.join(self.profile_dir.security_dir, self.connection_file)
+        else:
+            return self.connection_file
+        
 
     # streams, etc.
     no_stdout = Bool(False, config=True, help="redirect stdout to the null device")
@@ -141,7 +156,7 b' class KernelApp(BaseIPythonApplication):'
         """)
     interrupt = Integer(0, config=True,
         help="""ONLY USED ON WINDOWS
-        Interrupt this process when the parent is signalled.
+        Interrupt this process when the parent is signaled.
         """)
 
     def init_crash_handler(self):
@@ -158,11 +173,20 b' class KernelApp(BaseIPythonApplication):'
 
     def _bind_socket(self, s, port):
         iface = '%s://%s' % (self.transport, self.ip)
-        if port <= 0 and self.transport == 'tcp':
+        if self.transport == 'tcp':
+            if port <= 0:
             port = s.bind_to_random_port(iface)
         else:
-            c = ':' if self.transport == 'tcp' else '-'
-            s.bind(iface + c + str(port))
+                s.bind("tcp://%s:%i" % (self.ip, port))
+        elif self.transport == 'ipc':
+            if port <= 0:
+                for port in range(1,1024):
+                    path = "%s-%i" % (self.ip, port)
+                    if not os.path.exists(path):
+                        break
+            else:
+                path = "%s-%i" % (self.ip, port)
+            s.bind("ipc://%s" % path)
         return port
 
     def load_connection_file(self):
@@ -179,7 +203,7 b' class KernelApp(BaseIPythonApplication):'
             s = f.read()
         cfg = json.loads(s)
         self.transport = cfg.get('transport', self.transport)
-        if self.ip == LOCALHOST and 'ip' in cfg:
+        if self.ip == self._ip_default() and 'ip' in cfg:
             # not overridden by config or cl_args
             self.ip = cfg['ip']
         for channel in ('hb', 'shell', 'iopub', 'stdin'):
@@ -192,19 +216,15 b' class KernelApp(BaseIPythonApplication):'
     
     def write_connection_file(self):
         """write connection info to JSON file"""
-        if os.path.basename(self.connection_file) == self.connection_file:
-            cf = os.path.join(self.profile_dir.security_dir, self.connection_file)
-        else:
-            cf = self.connection_file
+        cf = self.abs_connection_file
+        self.log.debug("Writing connection file: %s", cf)
         write_connection_file(cf, ip=self.ip, key=self.session.key, transport=self.transport,
         shell_port=self.shell_port, stdin_port=self.stdin_port, hb_port=self.hb_port,
         iopub_port=self.iopub_port)
         
-        self._full_connection_file = cf
-    
     def cleanup_connection_file(self):
-        cf = self._full_connection_file
-        self.log.debug("cleaning up connection file: %r", cf)
+        cf = self.abs_connection_file
+        self.log.debug("Cleaning up connection file: %s", cf)
         try:
             os.remove(cf)
         except (IOError, OSError):

IPython/zmq/kernelmanager.py

@@ -684,7 +684,20 b' class KernelManager(Configurable):'
     
     transport = CaselessStrEnum(['tcp', 'ipc'], default_value='tcp', config=True)
 
-    ip = Unicode(LOCALHOST, config=True)
+    ip = Unicode(LOCALHOST, config=True,
+        help="""Set the kernel\'s IP address [default localhost].
+        If the IP address is something other than localhost, then
+        Consoles on other machines will be able to connect
+        to the Kernel, so be careful!"""
+    )
+    def _ip_default(self):
+        if self.transport == 'ipc':
+            if self.connection_file:
+                return os.path.splitext(self.connection_file)[0] + '-ipc'
+            else:
+                return 'kernel-ipc'
+        else:
+            return LOCALHOST
     def _ip_changed(self, name, old, new):
         if new == '*':
             self.ip = '0.0.0.0'