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3.\" Copyright (c) 2004 Apple Computer, Inc. All Rights Reserved.
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5.\" Licensed under the Apache License, Version 2.0 (the "License");
6.\" you may not use this file except in compliance with the License.
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14.\" See the License for the specific language governing permissions and
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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
33The
34.Nm
35command is a network diagnostic tool, much like
36.Xr ping 8
37or
38.Xr traceroute 8 .
39However, unlike those tools, most of its functionality is not implemented in the
40.Nm
41executable itself, but in library code that is available to any application.
42The library API that
43.Nm
44uses is documented in
45.Pa /usr/include/dns_sd.h .
46The
47.Nm
48command replaces the older
49.Xr mDNS 1
50command.
51.Pp
52The
53.Nm
54command is primarily intended for interactive use.
55Because its command-line arguments and output format are subject to change,
56invoking it from a shell script will generally be fragile. Additionally,
57the asynchronous nature of DNS Service Discovery does
58not lend itself easily to script-oriented programming. For example,
59calls like "browse" never complete; the action of performing a "browse"
60sets in motion machinery to notify the client whenever instances of
61that service type appear or disappear from the network. These
62notifications continue to be delivered indefinitely, for minutes,
63hours, or even days, as services come and go, until the client
64explicitly terminates the call. This style of asynchronous interaction
65works best with applications that are either multi-threaded, or use a
66main event-handling loop to receive keystrokes, network data, and other
67asynchronous event notifications as they happen.
68.br
69If you wish to perform DNS Service Discovery operations from a
70scripting language, then the best way to do this is not to execute the
71.Nm
72command and then attempt to decipher the textual output, but instead to
73directly call the DNS-SD APIs using a binding for your chosen language.
74.br
75For example, if you are programming in Ruby, then you can
76directly call DNS-SD APIs using the dnssd package documented at
77.Pa <http://rubyforge.org/projects/dnssd/> .
78.br
79Similar 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 ...
83register (advertise) a service in the specified
84.Ar domain
85with the given
86.Ar name
87and
88.Ar type
89as listening (on the current machine) on
90.Ar port.
91.Pp
92.Ar name
93can be arbitrary unicode text, containing any legal unicode characters
94(including dots, spaces, slashes, colons, etc. without restriction),
95up to 63 UTF-8 bytes long.
96.Ar type
97must 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
102is the domain in which to register the service.
103In current implementations, only the local multicast domain "local" is
104supported. In the future, registering will be supported in any arbitrary
105domain that has a working DNS Update server [RFC 2136]. The
106.Ar domain
107"." is a synonym for "pick a sensible default" which today
108means "local".
109.Pp
110.Ar port
111is a number from 0 to 65535, and is the TCP or UDP port number upon
112which the service is listening.
113.Pp
114Additional attributes of the service may optionally be described by
115key/value pairs, which are stored in the advertised service's DNS TXT
116record. Allowable keys and values are listed with the service
117registration at
118.Pa http://www.dns-sd.org/ServiceTypes.html .
119.It Nm Fl B Ar type domain
120browse for instances of service
121.Ar type
122in
123.Ar domain .
124.Pp
125For valid
126.Ar type Ns s
127see
128.Pa http://www.dns-sd.org/ServiceTypes.html
129as described above. Omitting the
130.Ar domain
131or using "." means "pick a sensible default."
132.It Nm Fl L Ar name type domain
133look up and display the information necessary to contact and use the
134named service: the hostname of the machine where that service is
135available, the port number on which the service is listening, and (if
136present) TXT record attributes describing properties of the service.
137.Pp
138Note that in a typical application, browsing happens rarely, while lookup
139(or "resolving") happens every time the service is used. For example, a
140user browses the network to pick a default printer fairly rarely, but once
141a default printer has been picked, that named service is resolved to its
142current IP address and port number every time the user presses Cmd-P to
143print.
144.El
145.Sh EXAMPLES
146.Pp
147To advertise the existence of LPR printing service on port 515 on this
148machine, such that it will be discovered by the Mac OS X printing software
149and 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
153For this registration to be useful, you need to actually have LPR service
154available on port 515. Advertising a service that does not exist is not
155very useful, and will be confusing and annoying to other people on the
156network.
157.Pp
158Similarly, to advertise a web page being served by an HTTP
159server on port 80 on this machine, such that it will show up in the
160Bonjour 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
164To find the advertised web pages on the local network (the same list that
165Safari shows), use:
166.Pp
167.Dl Nm Fl B Ns \ _http._tcp
168.Pp
169While that command is running, in another window, try the
170.Nm Fl R
171example given above to advertise a web page, and you should see the
172"Add" event reported to the
173.Nm Fl B
174window. Now press Ctrl-C in the
175.Nm Fl R
176window and you should see the "Remove" event reported to the
177.Nm Fl B
178window.
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
189bugs are tracked in Apple Radar component "mDNSResponder".
190.\"
191.Sh HISTORY
192The
193.Nm
194command first appeared in Mac OS X 10.4 (Tiger).
195