mDNSShared/dns-sd.1

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  17 .Dd April 2004              \" Date
  18 .Dt dns-sd 1                \" Document Title
  19 .Os Darwin                  \" Operating System
  20 .\"
  21 .Sh NAME
  22 .Nm dns-sd
  23 .Nd Multicast DNS (mDNS) & DNS Service Discovery (DNS-SD) Test Tool \" For whatis
  24 .\"
  25 .Sh SYNOPSIS
  26 .Nm Fl R Ar name type domain port Op Ar key=value ...
  27 .Pp
  28 .Nm Fl B Ar      type domain
  29 .Pp
  30 .Nm Fl L Ar name type domain
  31 .\"
  32 .Sh DESCRIPTION
  33 The
  34 .Nm
  35 command is a network diagnostic tool, much like
  36 .Xr ping 8
  37 or
  38 .Xr traceroute 8 .
  39 However, unlike those tools, most of its functionality is not implemented in the
  40 .Nm
  41 executable itself, but in library code that is available to any application.
  42 The library API that
  43 .Nm
  44 uses is documented in
  45 .Pa /usr/include/dns_sd.h .
  46 The
  47 .Nm
  48 command replaces the older
  49 .Xr mDNS 1
  50 command.
  51 .Pp
  52 The
  53 .Nm
  54 command is primarily intended for interactive use.
  55 Because its command-line arguments and output format are subject to change,
  56 invoking it from a shell script will generally be fragile. Additionally,
  57 the asynchronous nature of DNS Service Discovery does
  58 not lend itself easily to script-oriented programming. For example,
  59 calls like "browse" never complete; the action of performing a "browse"
  60 sets in motion machinery to notify the client whenever instances of
  61 that service type appear or disappear from the network. These
  62 notifications continue to be delivered indefinitely, for minutes,
  63 hours, or even days, as services come and go, until the client
  64 explicitly terminates the call. This style of asynchronous interaction
  65 works best with applications that are either multi-threaded, or use a
  66 main event-handling loop to receive keystrokes, network data, and other
  67 asynchronous event notifications as they happen.
  68 .br
  69 If you wish to perform DNS Service Discovery operations from a
  70 scripting language, then the best way to do this is not to execute the
  71 .Nm
  72 command and then attempt to decipher the textual output, but instead to
  73 directly call the DNS-SD APIs using a binding for your chosen language.
  74 .br
  75 For example, if you are programming in Ruby, then you can
  76 directly call DNS-SD APIs using the dnssd package documented at
  77 .Pa <http://rubyforge.org/projects/dnssd/> .
  78 .br
  79 Similar bindings for other languages are also in development.
  80 .Pp
  81 .Bl -tag -width R
  82 .It Nm Fl R Ar name type domain port Op Ar key=value ...
  83 register (advertise) a service in the specified
  84 .Ar domain
  85 with the given
  86 .Ar name
  87 and
  88 .Ar type
  89 as listening (on the current machine) on
  90 .Ar port.
  91 .Pp
  92 .Ar name
  93 can be arbitrary unicode text, containing any legal unicode characters
  94 (including dots, spaces, slashes, colons, etc. without restriction),
  95 up to 63 UTF-8 bytes long.
  96 .Ar type
  97 must be of the form "_app-proto._tcp" or "_app-proto._udp", where
  98 "app-proto" is an application protocol name registered at
  99 .Pa http://www.dns-sd.org/ServiceTypes.html .
 100 .Pp
 101 .Ar domain
 102 is the domain in which to register the service.
 103 In current implementations, only the local multicast domain "local" is
 104 supported. In the future, registering will be supported in any arbitrary
 105 domain that has a working DNS Update server [RFC 2136]. The
 106 .Ar domain
 107 "." is a synonym for "pick a sensible default" which today
 108 means "local".
 109 .Pp
 110 .Ar port
 111 is a number from 0 to 65535, and is the TCP or UDP port number upon
 112 which the service is listening.
 113 .Pp
 114 Additional attributes of the service may optionally be described by
 115 key/value pairs, which are stored in the advertised service's DNS TXT
 116 record. Allowable keys and values are listed with the service
 117 registration at
 118 .Pa http://www.dns-sd.org/ServiceTypes.html .
 119 .It Nm Fl B Ar type domain
 120 browse for instances of service
 121 .Ar type
 122 in
 123 .Ar domain .
 124 .Pp
 125 For valid
 126 .Ar type Ns s
 127 see
 128 .Pa http://www.dns-sd.org/ServiceTypes.html
 129 as described above. Omitting the
 130 .Ar domain
 131 or using "." means "pick a sensible default."
 132 .It Nm Fl L Ar name type domain
 133 look up and display the information necessary to contact and use the
 134 named service: the hostname of the machine where that service is
 135 available, the port number on which the service is listening, and (if
 136 present) TXT record attributes describing properties of the service.
 137 .Pp
 138 Note that in a typical application, browsing happens rarely, while lookup
 139 (or "resolving") happens every time the service is used. For example, a
 140 user browses the network to pick a default printer fairly rarely, but once
 141 a default printer has been picked, that named service is resolved to its
 142 current IP address and port number every time the user presses Cmd-P to
 143 print.
 144 .El
 145 .Sh EXAMPLES
 146 .Pp
 147 To advertise the existence of LPR printing service on port 515 on this
 148 machine, such that it will be discovered by the Mac OS X printing software
 149 and other DNS-SD compatible printing clients, use:
 150 .Pp
 151 .Dl Nm Fl R Ns \ \&"My Test\&" _printer._tcp. \&. 515 pdl=application/postscript
 152 .Pp
 153 For this registration to be useful, you need to actually have LPR service
 154 available on port 515. Advertising a service that does not exist is not
 155 very useful, and will be confusing and annoying to other people on the
 156 network.
 157 .Pp
 158 Similarly, to advertise a web page being served by an HTTP
 159 server on port 80 on this machine, such that it will show up in the
 160 Bonjour list in Safari and other DNS-SD compatible Web clients, use:
 161 .Pp
 162 .Dl Nm Fl R Ns \ \&"My Test\&" _http._tcp \&. 80 path=/path-to-page.html
 163 .Pp
 164 To find the advertised web pages on the local network (the same list that
 165 Safari shows), use:
 166 .Pp
 167 .Dl Nm Fl B Ns \ _http._tcp
 168 .Pp
 169 While that command is running, in another window, try the
 170 .Nm Fl R
 171 example given above to advertise a web page, and you should see the
 172 "Add" event reported to the
 173 .Nm Fl B
 174 window. Now press Ctrl-C in the
 175 .Nm Fl R
 176 window and you should see the "Remove" event reported to the
 177 .Nm Fl B
 178 window.
 179 .Pp
 180 .Sh FILES
 181 .Pa /usr/bin/dns-sd \" Pathname
 182 .\"
 183 .Sh SEE ALSO
 184 .Xr mDNS 1
 185 .Xr mDNSResponder 8
 186 .\"
 187 .Sh BUGS
 188 .Nm
 189 bugs are tracked in Apple Radar component "mDNSResponder".
 190 .\"
 191 .Sh HISTORY
 192 The
 193 .Nm
 194 command first appeared in Mac OS X 10.4 (Tiger).