Allow 'vagrant ssh' to strip most non-port options.

Adds a -p flag to 'vagrant ssh' which strips out username, private key
args, allowing the local user's ssh settings to take full effect.

lib/vagrant/command/ssh.rb

@@ -14,6 +14,12 @@ module Vagrant
           opts.on("-c", "--command COMMAND", "Execute an SSH command directly.") do |c|
             options[:command] = c
           end
+          opts.on(
+            "-p",
+            "Act like plain old 'ssh <my vm>', no extra flags"
+          ) do |c|
+            options[:port_only] = c
+          end
         end
 
         argv = parse_options(opts)
@@ -29,7 +35,7 @@ module Vagrant
           if options[:command]
             ssh_execute(vm, options[:command])
           else
-            ssh_connect(vm)
+            ssh_connect(vm, {:port_only => options[:port_only]})
           end
         end
       end
@@ -63,9 +69,9 @@ module Vagrant
         exit exit_status
       end
 
-      def ssh_connect(vm)
+      def ssh_connect(vm, opts)
         @logger.debug("`exec` into ssh prompt")
-        vm.ssh.connect
+        vm.ssh.connect(opts)
       end
     end
   end

lib/vagrant/ssh.rb

@@ -22,6 +22,9 @@ module Vagrant
     # Connects to the environment's virtual machine, replacing the ruby
     # process with an SSH process. This method optionally takes a hash
     # of options which override the configuration values.
+    # One specific option, :port_only, if set to true, will cause this method
+    # to skip filling in some default values, such as private_key_path and
+    # username.
     def connect(opts={})
       if Util::Platform.windows?
         raise Errors::SSHUnavailableWindows, :key_path => private_key_path,
@@ -30,6 +33,7 @@ module Vagrant
 
       raise Errors::SSHUnavailable if !Kernel.system("which ssh > /dev/null 2>&1")
 
+      port_only = opts[:port_only]
       options = {}
       options[:port] = port(opts)
       options[:private_key_path] = private_key_path
@@ -42,7 +46,8 @@ module Vagrant
       # Command line options
       command_options = ["-p #{options[:port]}", "-o UserKnownHostsFile=/dev/null",
                          "-o StrictHostKeyChecking=no", "-o IdentitiesOnly=yes",
-                         "-i #{options[:private_key_path]}", "-o LogLevel=ERROR"]
+                         "-o LogLevel=ERROR"]
+      command_options << "-i #{options[:private_key_path]}" unless port_only
       command_options << "-o ForwardAgent=yes" if @vm.config.ssh.forward_agent
 
       if @vm.config.ssh.forward_x11
@@ -51,7 +56,9 @@ module Vagrant
         command_options << "-o ForwardX11Trusted=yes"
       end
 
-      command = "ssh #{command_options.join(" ")} #{options[:username]}@#{options[:host]}".strip
+      host_string = options[:host]
+      host_string = "#{options[:username]}@" + host_string unless port_only
+      command = "ssh #{command_options.join(" ")} #{host_string}".strip
       @logger.info("Invoking SSH: #{command}")
       safe_exec(command)
     end