mDNSShared/dns-sd.1

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  22 .\" $Log: dns-sd.1,v $
  23 .\" Revision 1.2  2004/09/24 18:33:05  cheshire
  24 .\" <rdar://problem/3561780> Update man pages to clarify that mDNS and dns-sd are not intended for script use
  25 .\"
  26 .\" Revision 1.1  2004/09/22 22:46:25  cheshire
  27 .\" Man page for dns-sd command-line tool
  28 .\"
  29 .\"
  30 .\"
  31 .Dd April 2004              \" Date
  32 .Dt dns-sd 1                \" Document Title
  33 .Os Darwin                  \" Operating System
  34 .\"
  35 .Sh NAME
  36 .Nm dns-sd
  37 .Nd Multicast DNS Service Discovery (mDNS-SD) Test Tool \" For whatis
  38 .\"
  39 .Sh SYNOPSIS
  40 .Nm Fl R Ar name type domain port Op Ar key=value ...
  41 .Pp
  42 .Nm Fl B Ar      type domain
  43 .Pp
  44 .Nm Fl L Ar name type domain
  45 .\"
  46 .Sh DESCRIPTION
  47 The
  48 .Nm
  49 command is a network diagnostic tool, much like
  50 .Xr ping 8
  51 or
  52 .Xr traceroute 8 .
  53 However, unlike those tools, most of its functionality is not implemented in the
  54 .Nm
  55 executable itself, but in library code that is available to any application.
  56 The library API that
  57 .Nm
  58 uses is documented in
  59 .Pa /usr/include/dns_sd.h .
  60 The
  61 .Nm
  62 command replaces the older
  63 .Xr mDNS 1
  64 command.
  65 .Pp
  66 The
  67 .Nm
  68 command is primarily intended for interactive use.
  69 Because its command-line arguments and output format are subject to change,
  70 invoking it from a shell script will generally be fragile. Additionally,
  71 the asynchronous nature of DNS Service Discovery does
  72 not lend itself easily to script-oriented programming. For example,
  73 calls like "browse" never complete; the action of performing a "browse"
  74 sets in motion machinery to notify the client whenever instances of
  75 that service type appear or disappear from the network. These
  76 notifications continue to be delivered indefinitely, for minutes,
  77 hours, or even days, as services come and go, until the client
  78 explicitly terminates the call. This style of asynchronous interaction
  79 works best with applications that are either multi-threaded, or use a
  80 main event-handling loop to receive keystrokes, network data, and other
  81 asynchronous event notifications as they happen.
  82 .br
  83 If you wish to perform DNS Service Discovery operations from a
  84 scripting language, then the best way to do this is not to execute the
  85 .Nm
  86 command and then attempt to decipher the textual output, but instead to
  87 directly call the DNS-SD APIs using a binding for your chosen language.
  88 .br
  89 For example, if you are programming in Ruby, then you can
  90 directly call DNS-SD APIs using the dnssd package documented at
  91 .Pa <http://rubyforge.org/projects/dnssd/> .
  92 .br
  93 Similar bindings for other languages are also in development.
  94 .Pp
  95 .Bl -tag -width R
  96 .It Nm Fl R Ar name type domain port Op Ar key=value ...
  97 register (advertise) a service in the specified
  98 .Ar domain
  99 with the given
 100 .Ar name
 101 and
 102 .Ar type
 103 as listening (on the current machine) on
 104 .Ar port.
 105 .Pp
 106 .Ar name
 107 can be arbitrary unicode text, containing any legal unicode characters
 108 (including dots, spaces, slashes, colons, etc. without restriction),
 109 up to 63 UTF-8 bytes long.
 110 .Ar type
 111 must be of the form "_app-proto._tcp" or "_app-proto._udp", where
 112 "app-proto" is an application protocol name registered at
 113 .Pa http://www.dns-sd.org/ServiceTypes.html .
 114 .Pp
 115 .Ar domain
 116 is the domain in which to register the service.
 117 In current implementations, only the local multicast domain "local" is
 118 supported. In the future, registering will be supported in any arbitrary
 119 domain that has a working DNS Update server [RFC 2136]. The
 120 .Ar domain
 121 "." is a synonym for "pick a sensible default" which today
 122 means "local".
 123 .Pp
 124 .Ar port
 125 is a number from 0 to 65535, and is the TCP or UDP port number upon
 126 which the service is listening.
 127 .Pp
 128 Additional attributes of the service may optionally be described by
 129 key/value pairs, which are stored in the advertised service's DNS TXT
 130 record. Allowable keys and values are listed with the service
 131 registration at
 132 .Pa http://www.dns-sd.org/ServiceTypes.html .
 133 .It Nm Fl B Ar type domain
 134 browse for instances of service
 135 .Ar type
 136 in
 137 .Ar domain .
 138 .Pp
 139 For valid
 140 .Ar type Ns s
 141 see
 142 .Pa http://www.dns-sd.org/ServiceTypes.html
 143 as described above. Omitting the
 144 .Ar domain
 145 or using "." means "pick a sensible default."
 146 .It Nm Fl L Ar name type domain
 147 look up and display the information necessary to contact and use the
 148 named service: the hostname of the machine where that service is
 149 available, the port number on which the service is listening, and (if
 150 present) TXT record attributes describing properties of the service.
 151 .Pp
 152 Note that in a typical application, browsing happens rarely, while lookup
 153 (or "resolving") happens every time the service is used. For example, a
 154 user browses the network to pick a default printer fairly rarely, but once
 155 a default printer has been picked, that named service is resolved to its
 156 current IP address and port number every time the user presses Cmd-P to
 157 print.
 158 .El
 159 .Sh EXAMPLES
 160 .Pp
 161 To advertise the existence of LPR printing service on port 515 on this
 162 machine, such that it will be discovered by the Mac OS X printing software
 163 and other mDNS-SD compatible printing clients, use:
 164 .Pp
 165 .Dl Nm Fl R Ns \ \&"My Test\&" _printer._tcp. \&. 515 pdl=application/postscript
 166 .Pp
 167 For this registration to be useful, you need to actually have LPR service
 168 available on port 515. Advertising a service that does not exist is not
 169 very useful, and will be confusing and annoying to other people on the
 170 network.
 171 .Pp
 172 Similarly, to advertise a web page being served by an HTTP
 173 server on port 80 on this machine, such that it will show up in the
 174 Rendezvous list in Safari and other mDNS-SD compatible Web clients, use:
 175 .Pp
 176 .Dl Nm Fl R Ns \ \&"My Test\&" _http._tcp \&. 80 path=/path-to-page.html
 177 .Pp
 178 To find the advertised web pages on the local network (the same list that
 179 Safari shows), use:
 180 .Pp
 181 .Dl Nm Fl B Ns \ _http._tcp
 182 .Pp
 183 While that command is running, in another window, try the
 184 .Nm Fl R
 185 example given above to advertise a web page, and you should see the
 186 "Add" event reported to the
 187 .Nm Fl B
 188 window. Now press Ctrl-C in the
 189 .Nm Fl R
 190 window and you should see the "Remove" event reported to the
 191 .Nm Fl B
 192 window.
 193 .Pp
 194 .Sh FILES
 195 .Pa /usr/bin/dns-sd \" Pathname
 196 .\"
 197 .Sh SEE ALSO
 198 .Xr mDNS 1
 199 .Xr mDNSResponder 8
 200 .\"
 201 .Sh BUGS
 202 .Nm
 203 bugs are tracked in Apple Radar component "mDNSResponder".
 204 .\"
 205 .Sh HISTORY
 206 The
 207 .Nm
 208 command first appeared in Mac OS X 10.3 (Panther).