1 | .\" -*- tab-width: 4 -*- |
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2 | .\" |
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3 | .\" Copyright (c) 2003-2012 Apple Inc. All Rights Reserved. |
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4 | .\" |
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5 | .\" Licensed under the Apache License, Version 2.0 (the "License"); |
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6 | .\" you may not use this file except in compliance with the License. |
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7 | .\" You may obtain a copy of the License at |
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8 | .\" |
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9 | .\" http://www.apache.org/licenses/LICENSE-2.0 |
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10 | .\" |
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11 | .\" Unless required by applicable law or agreed to in writing, software |
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12 | .\" distributed under the License is distributed on an "AS IS" BASIS, |
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13 | .\" WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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14 | .\" See the License for the specific language governing permissions and |
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15 | .\" limitations under the License. |
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16 | .\" |
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17 | .Dd April 2004 \" Date |
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18 | .Dt mDNSResponder 8 \" Document Title |
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19 | .Os Darwin \" Operating System |
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20 | .\" |
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21 | .Sh NAME |
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22 | .Nm mDNSResponder |
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23 | .Nd Multicast and Unicast DNS daemon \" Name Description for whatis database |
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24 | .\" |
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25 | .Sh SYNOPSIS |
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26 | .Nm |
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27 | .\" |
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28 | .Sh DESCRIPTION |
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29 | .Nm |
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30 | (also known as |
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31 | .Nm mdnsd |
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32 | on some systems) |
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33 | is a daemon invoked at boot time to implement Multicast DNS and DNS Service Discovery. On |
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34 | Mac OS X 10.6 (Snow Leopard), |
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35 | .Nm |
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36 | is also the system-wide Unicast DNS Resolver. |
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37 | .Pp |
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38 | .Nm |
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39 | listens on UDP port 5353 for Multicast DNS Query packets. |
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40 | When it receives a query for which it knows an answer, |
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41 | .Nm |
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42 | issues the appropriate Multicast DNS Reply packet. |
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43 | .Pp |
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44 | .Nm |
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45 | also performs Unicast and Multicast DNS Queries on behalf of client processes, and |
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46 | maintains a cache of the replies. |
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47 | .Pp |
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48 | .Nm |
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49 | has no user-specifiable command-line argument, and users should not run |
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50 | .Nm |
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51 | manually. |
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52 | .Pp |
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53 | .Sh LOGGING |
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54 | There are several methods with which to examine |
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55 | .Nm Ns 's internal state for debugging and diagnostic purposes. The syslog(1) |
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56 | logging levels map as follows: |
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57 | .Pp |
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58 | .Dl Error - Error messages |
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59 | .Dl Warning - Client-initiated operations |
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60 | .Dl Notice - Sleep proxy operations |
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61 | .Dl Info - Informational messages |
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62 | .Pp |
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63 | By default, only log level Error is logged. |
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64 | .Pp |
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65 | A SIGUSR1 signal toggles additional logging, with Warning and Notice |
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66 | enabled by default: |
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67 | .Pp |
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68 | .Dl % sudo killall -USR1 mDNSResponder |
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69 | .Pp |
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70 | Once this logging is enabled, users can additionally use syslog(1) |
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71 | to change the log filter for the process. For example, to enable log levels Emergency - Debug: |
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72 | .Pp |
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73 | .Dl % sudo syslog -c mDNSResponder -d |
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74 | .Pp |
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75 | A SIGUSR2 signal toggles packet logging: |
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76 | .Pp |
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77 | .Dl % sudo killall -USR2 mDNSResponder |
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78 | .Pp |
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79 | A SIGINFO signal will dump a snapshot summary of the internal state to |
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80 | .Pa /var/log/system.log Ns : |
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81 | .Pp |
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82 | .Dl % sudo killall -INFO mDNSResponder |
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83 | .Sh OPTIONAL ARGUMENTS |
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84 | .Nm |
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85 | accepts the following optional arguments: |
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86 | .Bl -tag -width "AlwaysAppendSearchDomains" |
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87 | .It Fl AlwaysAppendSearchDomains |
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88 | Append search domains for multi-labeled Partially Qualified Domain Name as well as single-labeled Partially Qualified Domain Name. |
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89 | This argument is not recommended because of the extra DNS traffic it generates and its adverse effect on battery life. |
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90 | .It Fl NoMulticastAdvertisements |
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91 | Prevent the system from advertising Bonjour services via Multicast DNS. |
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92 | .El |
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93 | .Pp |
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94 | To cause |
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95 | .Nm |
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96 | to run with these optional arguments when it launches on OS X 10.11 (El Capitan) and later, set the |
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97 | .Sy AlwaysAppendSearchDomains |
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98 | or |
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99 | .Sy NoMulticastAdvertisements |
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100 | boolean keys to true in /Library/Preferences/com.apple.mDNSResponder.plist and reboot. |
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101 | .Pp |
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102 | .Sh FILES |
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103 | .Pa /usr/sbin/mDNSResponder |
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104 | .Pa /Library/Preferences/com.apple.mDNSResponder.plist |
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105 | .Pp |
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106 | .Sh INFO |
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107 | .Pp |
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108 | For information on Multicast DNS, see |
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109 | .Pa http://www.multicastdns.org/ |
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110 | .Pp |
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111 | For information on DNS Service Discovery, see |
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112 | .Pa http://www.dns-sd.org/ |
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113 | .Pp |
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114 | For information on how to use the Multicast DNS and the |
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115 | DNS Service Discovery APIs on Mac OS X and other platforms, see |
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116 | .Pa http://developer.apple.com/bonjour/ |
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117 | .Pp |
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118 | For the source code to |
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119 | .Nm , see |
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120 | .Pa http://developer.apple.com/darwin/projects/bonjour/ |
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121 | .\" |
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122 | .Sh BUGS |
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123 | .Nm |
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124 | bugs are tracked in Apple Radar component "mDNSResponder". |
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125 | .\" |
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126 | .Sh HISTORY |
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127 | The |
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128 | .Nm |
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129 | daemon first appeared in Mac OS X 10.2 (Jaguar). |
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130 | .Pp |
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131 | Also available from the Darwin open source repository |
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132 | (though not officially supported by Apple) are |
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133 | .Nm |
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134 | daemons for other platforms, including Microsoft Windows, |
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135 | Linux, FreeBSD, NetBSD, Solaris, and other POSIX systems. |
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