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14 <PRE> |
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15 <!-- Manpage converted by man2html 3.0.1 --> |
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16 <B><A HREF="dccifd.html">dccifd(8)</A></B> Distributed Checksum Clearinghouse <B><A HREF="dccifd.html">dccifd(8)</A></B> |
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17 |
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18 |
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19 </PRE> |
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20 <H2><A NAME="NAME">NAME</A></H2><PRE> |
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21 <B>dccifd</B> -- Distributed Checksum Clearinghouse Interface Daemon |
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22 |
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23 |
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24 </PRE> |
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25 <H2><A NAME="SYNOPSIS">SYNOPSIS</A></H2><PRE> |
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26 <B>dccifd</B> [<B>-VdbxANQ</B>] [<B>-G</B> <I>on</I> | <I>off</I> | <I>noIP</I> | <I>IPmask/xx</I>] [<B>-h</B> <I>homedir</I>] [<B>-I</B> <I>user</I>] |
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27 [<B>-p</B> <I>/sock</I> | <I>host,port,rhost/bits</I>] [<B>-o</B> <I>/sock</I> | <I>host,port</I>] |
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28 [<B>-D</B> <I>local-domain</I>] [<B>-m</B> <I>map</I>] [<B>-w</B> <I>whiteclnt</I>] [<B>-U</B> <I>userdirs</I>] |
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29 [<B>-a</B> <I>IGNORE</I> | <I>REJECT</I> | <I>DISCARD</I>] [<B>-t</B> <I>type,</I>[<I>log-thold,</I>]<I>rej-thold</I>] |
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30 [<B>-g</B> [<I>not-</I>]<I>type</I>] [<B>-S</B> <I>header</I>] [<B>-l</B> <I>logdir</I>] [<B>-R</B> <I>rundir</I>] |
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31 [<B>-r</B> <I>rejection-msg</I>] [<B>-T</B> <I>tmpdir</I>] [<B>-j</B> <I>maxjobs</I>] |
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32 [<B>-B</B> <I>dnsbl-option</I>] [<B>-L</B> <I>ltype,facility.level</I>] |
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33 |
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34 |
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35 </PRE> |
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36 <H2><A NAME="DESCRIPTION">DESCRIPTION</A></H2><PRE> |
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37 <B>dccifd</B> is a daemon intended to connect spam filters such as SpamAssasin |
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38 and mail transfer agents (MTAs) other than sendmail to DCC servers. The |
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39 MTA or filter <B>dccifd</B> which in turn reports related checksums to the near- |
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40 est DCC server and adds an <I>X-DCC</I> SMTP header line to the message. The |
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41 MTA is told to reject the message if it is unsolicited bulk. |
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42 |
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43 <B>Dccifd</B> is similar to the DCC sendmail milter interface, <B><A HREF="dccm.html">dccm(8)</A></B> and the |
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44 DCC Procmail interface, <B><A HREF="dccproc.html">dccproc(8)</A></B>. <B>Dccifd</B> is more efficient than |
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45 <B><A HREF="dccproc.html">dccproc(8)</A></B> but not restricted to use with sendmail like <B><A HREF="dccm.html">dccm(8)</A></B>. All |
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46 three send reports of checksums related to mail received by DCC clients |
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47 and queries about the total number of reports of particular checksums. |
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48 |
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49 MTA programs use a simple ASCII protocol a subset of SMTP to send a mail |
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50 message including its SMTP envelope to the daemon. <B>Dccifd</B> responds with |
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51 an indication of whether the message is unsolicited bulk and an optional |
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52 copy of the message with an <I>X-DCC</I> header added. The ASCII protocol is |
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53 described below and in the <I>include/dccif.h</I> file in the DCC source. There |
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54 is a sample C interface routine in the <I>dcclib/dccif.c</I> file in the DCC |
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55 source and the <I>dcclib.a</I> library generated from the source. A <I>Perl</I> ver- |
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56 sion of the interface routine is in <I>dccifd/dccif.pl</I>. Test or demonstra- |
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57 tion programs in the style of <B><A HREF="dccproc.html">dccproc(8)</A></B> that use those interface rou- |
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58 tines are in <I>dccifd/dccif-test</I>. |
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59 |
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60 A subset of ESMTP can be used instead of the ASCII protocol to connect |
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61 <B>dccifd</B> to postfix as a "Before-Queue Content Filter." See the <B>-o</B> flag. |
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62 |
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63 Since the checksums of messages that are whitelisted locally by the <B>-w</B> |
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64 <I>whiteclnt</I> file are not reported to the DCC server, <B>dccifd</B> knows nothing |
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65 about the total recipient counts for their checksums and so cannot add |
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66 <I>X-DCC</I> header lines to such messages. |
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67 |
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68 Enable the daemon and put its parameters in the <I>dcc</I><B>_</B><I>conf</I> file and start |
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69 the daemon with the <I>start-dccifd</I> script. |
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70 |
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71 The list of servers that <B>dccifd</B> contacts is in the memory mapped file <I>map</I> |
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72 shared by local DCC clients. The file is maintained with <B><A HREF="cdcc.html">cdcc(8)</A></B>. |
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73 |
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74 <A NAME="OPTIONS"><B>OPTIONS</B></A> |
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75 The following options are available: |
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76 |
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77 <A NAME="OPTION-V"><B>-V</B></A> displays the version of <B>dccifd</B>. |
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78 |
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79 <A NAME="OPTION-d"><B>-d</B></A> enables debugging output from the DCC client software. Additional |
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80 <B>-d</B> options increase the number of messages. A single <B>-d</B> |
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81 aborted SMTP transactions including those from some "dictionary |
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82 attacks." |
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83 |
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84 <A NAME="OPTION-b"><B>-b</B></A> causes the daemon to not detach itself from the controlling tty and |
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85 put itself into the background. |
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86 |
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87 <A NAME="OPTION-x"><B>-x</B></A> causes the daemon to try "extra hard" to contact a DCC server. |
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88 Since it is usually more important to deliver mail than to report |
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89 its checksums, <B>dccifd</B> normally does not delay too long while trying |
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90 to contact a DCC server. It will not try again for several seconds |
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91 after a failure. With <B>-x</B>, it will always try to contact the DCC |
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92 server and it will tell the MTA to answer the DATA command with a |
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93 4yz temporary failure. |
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94 |
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95 <A NAME="OPTION-A"><B>-A</B></A> adds to existing X-DCC headers in the message instead of replacing |
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96 existing headers of the brand of the current server. |
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97 |
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98 <A NAME="OPTION-N"><B>-N</B></A> neither adds, deletes, nor replaces existing X-DCC headers in the |
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99 message. Each message is logged, rejected, and otherwise handled |
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100 the same. |
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101 |
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102 <A NAME="OPTION-Q"><B>-Q</B></A> only queries the DCC server about the checksums of messages instead |
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103 of reporting and querying. This is useful when <B>dccifd</B> is used to |
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104 filter mail that has already been reported to a DCC server by |
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105 another DCC client. No single mail message should be reported to a |
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106 DCC server more than once per recipient, because each report will |
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107 increase the apparent "bulkness" of the message. |
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108 |
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109 It is better to use <I>MXDCC</I> lines in the global <I>whiteclnt</I> file for |
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110 your MX mail servers that use DCC than <B>-Q</B>. |
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111 |
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112 <A NAME="OPTION-G"><B>-G</B></A> <I>on</I> | <I>off</I> | <I>noIP</I> | <I>IPmask/xx</I> |
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113 controls <I>greylisting</I>. At least one working greylist server must be |
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114 listed in the <I>map</I> file in the DCC home directory. If more than one |
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115 is named, they must "flood" or change checksums and they must use |
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116 the same <B>-G</B> parameters. See <B><A HREF="dccd.html">dccd(8)</A></B>. Usually all dccm or dccifd |
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117 DCC client processes use the same <B>-G</B> parameters. |
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118 |
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119 <I>IPmask/xx</I> and <I>noIP</I> remove part or all of the IP address from the |
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120 greylist triple. The CIDR block size, <I>xx</I>, must be between 1 and |
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121 128. 96 is added to block sizes smaller than 33 to make them appro- |
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122 priate for the IPv6 addresses used by the DCC. <I>IPmask/96</I> differs |
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123 from <I>noIP</I> for IPv4 addresses, because the former retains the IPv4 to |
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124 IPv6 mapping prefix. |
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125 |
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126 <A NAME="OPTION-h"><B>-h</B></A> <I>homedir</I> |
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127 overrides the default DCC home directory, <I>@prefix@</I>. |
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128 |
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129 <A NAME="OPTION-I"><B>-I</B></A> <I>user</I> |
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130 specifies the UID and GID of the process. |
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131 |
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132 <A NAME="OPTION-p"><B>-p</B></A> <I>/sock/name</I> | <I>host,port,rhost/bits</I> |
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133 overrides the default address at which programs contact <B>dccifd</B>. The |
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134 default is a UNIX domain socket named dccifd in the DCC home direc- |
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135 tory. |
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136 |
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137 The second form specifies a local host name or IP address, a local |
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138 TCP port number, and the host names or IP addresses of computers |
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139 that can use <B>dccifd</B>. 127.0.0.1 or <I>localhost</I> are common choices for |
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140 <I>host</I>. The string <I>@</I> specifies IN_ADDRANY or all local IP addresses. |
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141 127.0.0.0/8 is a common choice for <I>rhost/bits</I>. |
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142 |
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143 <A NAME="OPTION-o"><B>-o</B></A> <I>/sock</I> | <I>host,port</I> |
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144 enables SMTP proxy mode instead of the ASCII protocol and specifies |
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145 the output connection when <B>dccifd</B> acts as an SMTP proxy. It is the |
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146 address of the SMTP server for which <B>dccifd</B> acts as SMTP client. |
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147 When <I>/sock</I> is <I>/dev/null</I>, <B>dccifd</B> acts as if there were downstream |
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148 SMTP server that always answers "250 ok". The string <I>@</I> specifies |
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149 the same IP address as the incoming TCP connection. |
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150 |
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151 The input to <B>dccifd</B> in SMTP proxy mode is specified with <B>--p</B>. For |
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152 example, <B>-p</B> <I>127.0.0.1,10025,127.0.0.1/32</I> <B>-o</B> <I>127.0.0.1,10026</I> could be |
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153 used to connect <B>dccifd</B> with Postfix as described in the documenta- |
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154 tion in version 2.2.1 Postfix documentation. |
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155 |
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156 See below concerning the subset of ESMTP used in this mode. |
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157 |
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158 <A NAME="OPTION-m"><B>-m</B></A> <I>map</I> |
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159 specifies a name or path of the memory mapped parameter file instead |
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160 of the default <I>map</I> file in the DCC home directory. It should be |
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161 created with the <B><A HREF="cdcc.html">cdcc(8)</A></B> command. |
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162 |
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163 <A NAME="OPTION-w"><B>-w</B></A> <I>whiteclnt</I> |
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164 specifies an optional file containing filtering parameters as well |
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165 as SMTP client IP addresses, SMTP envelope values, and header values |
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166 of mail that is spam or is not spam and does not need a <I>X-DCC</I> |
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167 header, and whose checksums should not be reported to the DCC |
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168 server. |
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169 |
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170 If the pathname <I>whiteclnt</I> is not absolute, it is relative to the DCC |
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171 home directory. |
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172 |
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173 The format of the <B>dccifd</B> whiteclnt file is the same as the <I>whitelist</I> |
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174 files used by <B><A HREF="dbclean.html">dbclean(8)</A></B> and the <I>whiteclnt</I> file used by <B><A HREF="dccproc.html">dccproc(8)</A></B>. |
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175 See <B><A HREF="dcc.html">dcc(8)</A></B> for a description of DCC white and blacklists. Because |
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176 the contents of the <I>whiteclnt</I> file are used frequently, a companion |
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177 file is automatically created and maintained. It has the same path- |
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178 name but with an added suffix of <I>.dccw</I> and contains a memory mapped |
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179 hash table of the main file. |
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180 |
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181 A whitelist entry ("OK") or two or more semi-whitelistings ("OK2") |
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182 for one of the message's checksums prevents all of the message's |
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183 checksums from being reported to the DCC server and the addition of |
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184 a <I>X-DCC</I> header line by <B>dccifd</B> A whitelist entry for a checksum also |
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185 prevents rejecting or discarding the message based on DCC recipient |
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186 counts as specified by <B>-a</B> and <B>-t</B>. Otherwise, one or more checksums |
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187 with blacklisting entries ("MANY") cause all of the message's check- |
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188 sums to be reported to the server with an addressee count of "MANY". |
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189 |
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190 If the message has a single recipient, an <I>env</I><B>_</B><I>To</I> <I>whiteclnt</I> entry of |
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191 "OK" for the checksum of its recipient address acts like any other |
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192 <I>whiteclnt</I> entry of "OK." When the SMTP message has more than one |
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193 recipient, the effects can be complicated. When a message has sev- |
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194 eral recipients with some but not all listed in the <I>whiteclnt</I> file, |
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195 <B>dccifd</B> tries comply with the wishes of the users who want filtering |
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196 as well as those who don't by silently not delivering the message to |
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197 those who want filtering (i.e. are not whitelisted) and delivering |
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198 the message to don't want filtering. |
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199 |
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200 <A NAME="OPTION-U"><B>-U</B></A> <I>userdirs</I> |
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201 enables per-user <I>whiteclnt</I> files and log directories. Each target |
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202 of a message can have a directory of log files named |
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203 <I>userdirs/addr/log</I> where <I>addr</I> is the local user or mailbox name com- |
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204 puted by the MTA. The name of each user's log directory must be |
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205 <I>log</I>. If it is not absolute, <I>userdirs</I> is relative to the DCC home |
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206 directory. The directory containing the log files must be named <I>log</I> |
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207 and it must be writable by the <B>dccifd</B> process. Each log directory |
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208 must exist or logging for the corresponding is silently disabled. |
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209 The files created in the log directory are owned by the UID of the |
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210 <B>dccifd</B> process, but they have <I>group</I> and <I>other</I> read and write permis- |
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211 sions copied from the corresponding <I>log</I> directory. To ensure the |
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212 privacy of mail, it may be good to make the directories readable |
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213 only by <I>owner</I> and <I>group</I>, and to use a cron script that changes the |
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214 owner of each file to match the grandparent <I>addr</I> directory. |
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215 |
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216 There can also be a per -user whitelist file named |
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217 <I>userdirs/addr/whiteclnt</I> for each address <I>addr.</I> Any checksum that is |
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218 not white- or blacklisted by an individual addressee's <I>whiteclnt</I> |
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219 file is checked in the main <B>-w -whiteclnt</B> file. A missing per- |
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220 addressee <I>whiteclnt</I> file is the same as an empty file. Relative |
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221 paths for files included in per-addressee files are resolved in the |
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222 DCC home directory. The <I>whiteclnt</I> files and the <I>addr</I> directories |
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223 containing them must be writable by the <B>dccifd</B> process. |
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224 |
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225 <I>Option</I> lines in per-user whiteclnt files can be used to modify many |
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226 aspects of <B>dccifd</B> filtering, as described in the main dcc man page. |
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227 For example, an <I>option</I> <I>dcc-off</I> line turns off DCC filtering for |
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228 individual mailboxes. |
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229 |
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230 <A NAME="OPTION-a"><B>-a</B></A> <I>IGNORE</I> | <I>REJECT</I> | <I>DISCARD</I> |
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231 specifies the action taken when <B>dccifd</B> is in proxy mode with <B>-o</B> and |
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232 DCC server counts or <B>-t</B> thresholds say that a message is unsolicited |
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233 and bulk. <I>IGNORE</I> causes the message to be unaffected except for |
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234 adding the <I>X-DCC</I> header line to the message. This turns off DCC |
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235 filtering. |
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236 |
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237 Spam can also be <I>REJECT</I>ed or (when in proxy mode with <B>-o</B>) accepted |
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238 and silently <I>DISCARD</I>ed without being delivered to local mailboxes. |
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239 The default is <I>REJECT</I>. |
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240 |
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241 Mail forwarded via IP addresses marked <I>MX</I> or <I>MXDCC</I> in the main |
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242 <I>whiteclnt</I> file is treated as if <B>-a</B> <I>DISCARD</I> were specified. This |
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243 prevents "bouncing" spam. |
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244 |
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245 The effects of the <B>-w</B> <I>whiteclnt</I> are not affected by <B>-a</B>. |
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246 |
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247 <A NAME="OPTION-t"><B>-t</B></A> <I>type,</I>[<I>log-thold,</I>]<I>rej-thold</I> |
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248 sets logging and "spam" thresholds for checksum <I>type</I>. The checksum |
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249 types are <I>IP</I>, <I>env</I><B>_</B><I>From</I>, <I>From</I>, <I>Message-ID</I>, <I>substitute</I>, <I>Received</I>, |
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250 <I>Body</I>, <I>Fuz1</I>, <I>Fuz2</I>, <I>rep-total</I>, and <I>rep</I>. The first six, <I>IP</I> through |
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251 <I>substitute</I>, have no effect except when a local DCC server configured |
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252 with <B>-K</B> is used. The <I>substitute</I> thresholds apply to the first sub- |
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253 stitute heading encountered in the mail message. The string <I>ALL</I> |
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254 sets thresholds for all types, but is unlikely to be useful except |
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255 for setting logging thresholds. The string <I>CMN</I> specifies the com- |
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256 monly used checksums <I>Body</I>, <I>Fuz1</I>, and <I>Fuz2</I>. <I>Rej-thold</I> and <I>log-thold</I> |
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257 must be numbers, the string <I>NEVER</I>, or the string <I>MANY</I> indicating |
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258 millions of targets. Counts from the DCC server as large as the |
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259 threshold for any single type are taken as sufficient evidence that |
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260 the message should be logged or rejected. |
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261 |
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262 <I>Log-thold</I> is the threshold at which messages are logged. It can be |
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263 handy to log messages at a lower threshold to find solicited bulk |
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264 mail sources such as mailing lists. If no logging threshold is set, |
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265 only rejected mail and messages with complicated combinations of |
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266 white and blacklisting are logged. Messages that reach at least one |
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267 of their rejection thresholds are logged regardless of logging |
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268 thresholds. |
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269 |
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270 <I>Rej-thold</I> is the threshold at which messages are considered "bulk," |
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271 and so should be rejected or discarded if not whitelisted. |
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272 |
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273 DCC Reputation thresholds in the commercial version of the DCC are |
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274 controlled by thresholds on checksum types <I>rep</I> and <I>rep-total</I>. Mes- |
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275 sages from an IP address that the DCC database says has sent more |
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276 than <B>-t</B> <I>rep-total,log-thold</I> messages are logged. A DCC Reputation |
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277 is computed for messages received from IP addresses that have sent |
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278 more than <B>-t</B> <I>rep-total,log-thold</I> messages. The DCC Reputation of an |
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279 IP address is the percentage of its messages that have been detected |
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280 as bulk or having at least 10 recipients. The defaults are equiva- |
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281 lent to <B>-t</B> <I>rep,never</I> and <B>-t</B> <I>rep-total,never,20</I>. |
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282 |
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283 Bad DCC Reputations do not reject mail unless enabled by an <I>option</I> |
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284 <I>DCC-rep-on</I> line in a <I>whiteclnt</I> file. |
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285 |
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286 The checksums of locally whitelisted messages are not checked with |
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287 the DCC server and so only the number of targets of the current copy |
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288 of a whitelisted message are compared against the thresholds. |
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289 |
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290 The default is <I>ALL,NEVER</I>, so that nothing is discarded, rejected, or |
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291 logged. A common choice is <I>CMN,25,50</I> to reject or discard mail with |
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292 common bodies except as overridden by the whitelist of the DCC |
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293 server, the sendmail <I>${dcc</I><B>_</B><I>isspam}</I> and <I>${dcc</I><B>_</B><I>notspam}</I> macros, and |
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294 <B>-g</B>, and <B>-w</B>. |
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295 |
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296 <A NAME="OPTION-g"><B>-g</B></A> [<I>not-</I>]<I>type</I> |
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297 indicates that whitelisted, <I>OK</I> or <I>OK2</I>, counts from the DCC server |
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298 for a type of checksum are to be believed. They should be ignored |
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299 if prefixed with <I>not-</I>. <I>Type</I> is one of the same set of strings as |
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300 for <B>-t</B>. Only <I>IP</I>, <I>env</I><B>_</B><I>From</I>, and <I>From</I> are likely choices. By default |
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301 all three are honored, and hence the need for <I>not-</I>. |
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302 |
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303 <A NAME="OPTION-S"><B>-S</B></A> <I>hdr</I> |
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304 adds to the list of substitute or locally chosen headers that are |
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305 checked with the <B>-w</B> <I>whiteclnt</I> file and sent to the DCC server. The |
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306 checksum of the last header of type <I>hdr</I> found in the message is |
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307 checked. <I>Hdr</I> can be <I>HELO</I> to specify the SMTP envelope HELO value. |
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308 <I>Hdr</I> can also be <I>mail</I><B>_</B><I>host</I> to specify the host name from the |
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309 Mail_from value in the SMTP envelope. As many as six different sub- |
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310 stitute headers can be specified, but only the checksum of the first |
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311 of the six will be sent to the DCC server. |
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312 |
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313 <A NAME="OPTION-l"><B>-l</B></A> <I>logdir</I> |
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314 specifies a directory in which files containing copies of messages |
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315 processed by <B>dccifd</B> are kept. They can be copied to per-user direc- |
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316 tories specified with <B>-U</B>. Information about other recipients of a |
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317 message is deleted from the per-user copies. |
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318 |
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319 See the FILES section below concerning the contents of the files. |
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320 See also the <I>option</I> <I>log-subdirectory-{day,hour,minute}</I> lines in |
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321 <I>whiteclnt</I> files described in <B><A HREF="dcc.html">dcc(8)</A></B>. |
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322 |
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323 The directory is relative to the DCC home directory if it is not |
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324 absolute |
|
325 |
|
326 <A NAME="OPTION-R"><B>-R</B></A> <I>rundir</I> |
|
327 specifies the "run" directory where the file containing the daemon's |
|
328 process ID is stored. The default value is <I>@dcc_rundir@</I>. |
|
329 |
|
330 <A NAME="OPTION-T"><B>-T</B></A> <I>tmpdir</I> |
|
331 changes the default directory for temporary files from the default. |
|
332 The default is the directory specified with <B>-l</B> or the system default |
|
333 if <B>-l</B> is not used. The system default is often <I>/tmp</I>. |
|
334 |
|
335 <A NAME="OPTION-D"><B>-D</B></A> <I>local-domain</I> |
|
336 specifies a host or domain name by which the system is known. There |
|
337 can be several <B>-D</B> settings. |
|
338 |
|
339 To find the per-user log directory and whitelist for each mail |
|
340 recipient, <B>dccifd</B> must know each recipient's user name. The ASCII |
|
341 protocol used between and the MTA includes an optional user name |
|
342 with each SMTP recipient address. When the user name is absent when |
|
343 the ASCII protocol is used or when the subset of ESMTP enabled with |
|
344 <B>-o</B> is used, and when the SMTP recipient address includes an <I>at</I> <I>sign</I> |
|
345 (@) each mail address is checked against the list of <I>local-domain</I>s. |
|
346 The part of the recipient address remaining after longest matching |
|
347 <I>local-domain</I> (if any) is taken as the user name. The match is |
|
348 anchored at the right or the end of the recipient address. It must |
|
349 start at a period (.) or <I>at</I> <I>sign</I> (@) in the domain name part of the |
|
350 address. |
|
351 |
|
352 If <I>local-domain</I> starts with an asterisk (*) indicating a wildcard, |
|
353 preceding sub-domain names are discarded to compute the user name. |
|
354 Otherwise, the computed user name will include any unmatched sub- |
|
355 domain names. |
|
356 |
|
357 The default value of <I>local-domain</I> when there are no <B>-D</B> settings is |
|
358 the host name of the system. |
|
359 |
|
360 <A NAME="OPTION-r"><B>-r</B></A> <I>rejection-msg</I> |
|
361 specifies the rejection message in <B>-o</B> proxy mode for unsolicited |
|
362 bulk mail or for mail temporarily blocked by <I>greylisting</I> when <B>-G</B> is |
|
363 specified. The first <B>-r</B> <I>rejection-msg</I> replaces the default bulk |
|
364 mail rejection message, "5.7.1 550 mail %ID from %CIP rejected by |
|
365 DCC". The second replaces "4.2.1 452 mail %ID from %CIP temporary |
|
366 greylist embargoed". The third <B>-r</B> <I>rejection-msg</I> replaces the |
|
367 default SMTP rejection message "5.7.1 550 %ID bad reputation; see |
|
368 http://commercial-dcc.rhyolite.com/cgi-bin/reps.cgi?tgt=%CIP" for |
|
369 mail with bad DCC Reputations. If <I>rejection-msg</I> is the zero-length |
|
370 string, the <B>-r</B> setting is counted but the corresponding message is |
|
371 not changed. |
|
372 |
|
373 <I>Rejection-msg</I> can contain specific information about the mail mes- |
|
374 sage. The following strings starting with % are replaced with the |
|
375 corresponding values: |
|
376 %ID message ID such as the unique part of log file name or |
|
377 sendmail queue ID |
|
378 %CIP SMTP client IP address |
|
379 %BTYPE type of DNS blacklist hit, such as "SMTP client", |
|
380 "mail_host", or "URL NS" |
|
381 %BTGT IP address or name declared bad by DNS blacklist |
|
382 %BPROBE domain name found in DNS blacklist such as |
|
383 4.3.2.10.example.com |
|
384 %BRESULT value of the %BPROBE domain name found in DNS black- |
|
385 list |
|
386 |
|
387 A common alternate for the bulk mail rejection message is "4.7.1 451 |
|
388 Access denied by DCC" to tell the sending mail system to continue |
|
389 trying. Use a 4yz response with caution, because it is likely to |
|
390 delay for days a delivery failure message for false positives. If |
|
391 the rejection message does not start with an RFC 1893 status code |
|
392 and RFC 2821 reply code, 5.7.1 and 550 or 4.2.1 and 452 are used. |
|
393 |
|
394 See also <B>-B</B> <I>set:rej-msg=rejection-msg</I> to set the status message for |
|
395 mail rejected by DNS blacklists. |
|
396 |
|
397 <A NAME="OPTION-j"><B>-j</B></A> <I>maxjobs</I> |
|
398 limits the number of simultaneous requests that will be processed. |
|
399 The default value is the maximum number that seems to be possible |
|
400 given system limits on open files, select() bit masks, and so forth. |
|
401 Start <B>dccifd</B> with <B>-d</B> and see the starting message in the system log |
|
402 to see the limit. |
|
403 |
|
404 <A NAME="OPTION-B"><B>-B</B></A> <I>dnsbl-option</I> |
|
405 enables DNS blacklist checks of the SMTP client IP address, SMTP |
|
406 envelope Mail_From sender domain name, and of host names in URLs in |
|
407 the message body. Body URL blacklisting has too many false posi- |
|
408 tives to use on abuse mailboxes. It is less effective than |
|
409 greylisting with <B><A HREF="dccm.html">dccm(8)</A></B> or <B><A HREF="dccifd.html">dccifd(8)</A></B> but can be useful in situa- |
|
410 tions where greylisting cannot be used. |
|
411 |
|
412 <I>Dnsbl-option</I> is either one of the <B>-B</B> <I>set:option</I> forms or |
|
413 <B>-B</B> <I>domain</I>[<I>,IPaddr</I>[<I>/xx</I>[<I>,bltype</I>]]] |
|
414 <I>Domain</I> is a DNS blacklist domain such as example.com that will be |
|
415 searched. <I>IPaddr</I>[<I>/xxx</I>] is the string "any" an IP address in the DNS |
|
416 blacklist that indicates that the mail message should be rejected, |
|
417 or a CIDR block covering results from the DNS blacklist. |
|
418 "127.0.0.2" is assumed if <I>IPaddr</I> is absent. IPv6 addresses can be |
|
419 specified with the usual colon (:) notation. Names can be used |
|
420 instead of numeric addresses. The type of DNS blacklist is speci- |
|
421 fied by <I>bltype</I> as <I>name</I>, <I>IPv4</I>, or <I>IPv6</I>. Given an envelope sender |
|
422 domain name or a domain name in a URL of spam.domain.org and a |
|
423 blacklist of type <I>name</I>, spam.domain.org.example.com will be tried. |
|
424 Blacklist types of <I>IPv4</I> and <I>IPv6</I> require that the domain name in a |
|
425 URL sender address be resolved into an IPv4 or IPv6 address. The |
|
426 address is then written as a reversed string of decimal octets to |
|
427 check the DNS blacklist, as in 2.0.0.127.example.com, |
|
428 |
|
429 More than one blacklist can be specified and blacklists can be |
|
430 grouped. All searching within a group is stopped at the first posi- |
|
431 tive result. |
|
432 |
|
433 Positive results are ignored after being logged unless an |
|
434 <I>option</I> <I>DNSBL-on</I> line appears in the global or per-user <I>whiteclnt</I> |
|
435 file. |
|
436 |
|
437 <B>-B</B> <I>set:no-client</I> |
|
438 says that SMTP client IP addresses and reverse DNS domain names |
|
439 should not be checked in the following blacklists. |
|
440 <B>-B</B> <I>set:client</I> restores the default for the following black- |
|
441 lists. |
|
442 |
|
443 <B>-B</B> <I>set:no-mail</I><B>_</B><I>host</I> |
|
444 says that SMTP envelope Mail_From sender domain names should |
|
445 not be checked in the following blacklists. <B>-B</B> <I>set:mail</I><B>_</B><I>host</I> |
|
446 restores the default. |
|
447 |
|
448 <B>-B</B> <I>set:no-URL</I> |
|
449 says that URLs in the message body should not be checked in the |
|
450 in the following blacklists. <B>-B</B> <I>set:URL</I> restores the default. |
|
451 |
|
452 <B>-B</B> <I>set:no-MX</I> |
|
453 says MX servers of sender Mail_From domain names and host names |
|
454 in URLs should not be checked in the following blacklists. |
|
455 <B>-B</B> <I>set:MX</I> restores the default. |
|
456 |
|
457 <B>-B</B> <I>set:no-NS</I> |
|
458 says DNS servers of sender Mail_From domain names and host |
|
459 names in URLs should not be checked in the following black- |
|
460 lists. <B>-B</B> <I>set:NS</I> restores the default. |
|
461 |
|
462 <B>-B</B> <I>set:defaults</I> |
|
463 is equivalent to all of <B>-B</B> <I>set:no-temp-fail</I> <B>-B</B> <I>set:client</I> |
|
464 <B>-B</B> <I>set:mail</I><B>_</B><I>host</I> <B>-B</B> <I>set:URL</I> <B>-B</B> <I>set:MX</I> and <B>-B</B> <I>set:NS</I> |
|
465 |
|
466 <B>-B</B> <I>set:group=X</I> |
|
467 adds later DNS blacklists specified with |
|
468 <B>-B</B> <I>domain</I>[<I>,IPaddr</I>[<I>/xx</I>[<I>,bltype</I>]]] |
|
469 to group 1, 2, or 3. |
|
470 |
|
471 <B>-B</B> <I>set:debug=X</I> |
|
472 sets the DNS blacklist logging level |
|
473 |
|
474 <B>-B</B> <I>set:msg-secs=S</I> |
|
475 limits <B>dccifd</B> to <I>S</I> seconds total for checking all DNS black- |
|
476 lists. The default is 25. |
|
477 |
|
478 <B>-B</B> <I>set:URL-secs=S</I> |
|
479 limits <B>dccifd</B> to at most <I>S</I> seconds resolving and checking any |
|
480 single URL. The default is 11. Some spam contains dozens of |
|
481 URLs and that some "spamvertised" URLs contain host names that |
|
482 need minutes to resolve. Busy mail systems cannot afford to |
|
483 spend minutes checking each incoming mail message. |
|
484 |
|
485 <B>-B</B> <I>set:rej-msg=rejection-msg</I> |
|
486 sets the SMTP rejection message for the following blacklists. |
|
487 <I>Rejection-msg</I> must be in the same format as for <B>-r</B>. If |
|
488 <I>rejection-msg</I> is null, the default is restored. The default |
|
489 DNS blacklist rejection message is the first message set with |
|
490 <B>-r</B>. |
|
491 |
|
492 <B>-B</B> <I>set:temp-fail</I> |
|
493 causes <B>dccifd</B> to the MTA to answer the SMTP DATA command with |
|
494 452 4.2.1 mail %ID from %CIP temporary delayed for DNSBL |
|
495 if any DNS answer required for a DNSBL in the current group |
|
496 times out, including resolving names in URLs. |
|
497 |
|
498 <B>-B</B> <I>set:no-temp-fail</I> |
|
499 restores the default of assuming a negative answer for DNS |
|
500 responses that take too long. |
|
501 |
|
502 <B>-B</B> <I>set:maxjobs=X</I> |
|
503 sets maximum number of helper processes to <I>X</I>. In order to use |
|
504 typical single-threaded DNS resolver libraries, <B>dccifd</B> uses |
|
505 fleets of helper processes. It is rarely a good idea to change |
|
506 the default, which is the same as the maximum number of simul- |
|
507 taneous jobs set with <B>-j</B>. |
|
508 |
|
509 <B>-B</B> <I>set:progpath=@libexecdir@/dns-helper</I> |
|
510 changes the path to the helper program. |
|
511 |
|
512 <A NAME="OPTION-L"><B>-L</B></A> <I>ltype,facility.level</I> |
|
513 specifies how messages should be logged. <I>Ltype</I> must be <I>error</I>, <I>info</I>, |
|
514 or <I>off</I> to indicate which of the two types of messages are being con- |
|
515 trolled or to turn off all <B>syslog(3)</B> messages from <B>dccifd</B>. <I>Level</I> |
|
516 must be a <B>syslog(3)</B> level among <I>EMERG</I>, <I>ALERT</I>, <I>CRIT</I>, <I>ERR</I>, <I>WARNING</I>, |
|
517 <I>NOTICE</I>, <I>INFO</I>, and <I>DEBUG</I>. <I>Facility</I> must be among <I>AUTH</I>, <I>AUTHPRIV</I>, |
|
518 <I>CRON</I>, <I>DAEMON</I>, <I>FTP</I>, <I>KERN</I>, <I>LPR</I>, <I>MAIL</I>, <I>NEWS</I>, <I>USER</I>, <I>UUCP</I>, and <I>LOCAL0</I> |
|
519 through <I>LOCAL7</I>. The default is equivalent to |
|
520 <B>-L</B> <I>info,MAIL.NOTICE</I> <B>-L</B> <I>error,MAIL.ERR</I> |
|
521 |
|
522 <B>dccifd</B> normally sends counts of mail rejected and so forth to the system |
|
523 log at midnight. The SIGUSR1 signal sends an immediate report to the |
|
524 system log. The reports will be repeated every 24 hours at the same |
|
525 minute as the signal instead of at midnight. |
|
526 |
|
527 <A NAME="Protocol"><B>Protocol</B></A> |
|
528 <B>Dccifd</B> uses a simple ASCII protocol to receive mail messages to be |
|
529 checked and to return results. For each message, the MTA must open a |
|
530 connection to the interface daemon, send options, envelope recipients, |
|
531 and the message, receive the results, and close the connection. |
|
532 |
|
533 Instead of the ASCII protocol, a subset of ESMTP is enabled by <B>-o</B>. Only |
|
534 the familiar HELO, EHLO, Mail, Rcpt, DATA, RSET, and QUIT commands and |
|
535 the Postfix extensions XFORWARD and XCLIENT are honored. Since SMTP has |
|
536 no provisions for user names, the protocol enabled by <B>-o</B> depends on a |
|
537 list of local domain names specified with <B>-D</B> to find per-user log direc- |
|
538 tories and whitelist files. If neither XFORWARD nor XCLIENT are used, |
|
539 <B>dccifd</B> uses the IP address of the MTA and the value of the HELO command. |
|
540 |
|
541 In the ASCII protocol, each of the following lines are sent in order to |
|
542 <B>dccifd</B>. Each ends with a newline ('\n') character. |
|
543 options zero or more blank-separated strings among: |
|
544 <I>spam</I> the message is already known to be spam |
|
545 <I>body</I> return all of the headers with the added |
|
546 <I>X-DCC</I> header line and the body |
|
547 <I>header</I> return the <I>X-DCC</I> header |
|
548 <I>query</I> ask the DCC server about the message without |
|
549 reporting it, as if <B>dccifd</B> were running with |
|
550 <B>-Q</B>. |
|
551 <I>grey-query</I> only query the greylist server for this mes- |
|
552 sage. <B>-G</B> <I>on</I> must be in use. |
|
553 <I>no-reject</I> suppress the overall, one character line 'R' |
|
554 result. This can be useful when using <B>dccifd</B> |
|
555 only for greylisting. |
|
556 <I>log</I> ensure that this message is logged as if |
|
557 <B>dccifd</B> were running with <B>-t -all,0,</B> |
|
558 client IP address of the SMTP client in a "dotted" or "coloned" |
|
559 ASCII string and reverse-DNS host name. If the host name |
|
560 is present, it must follow a carriage return character |
|
561 ('\r') after the IP address. The client IP address must be |
|
562 present and non-null if the host name is present. The |
|
563 string "0.0.0.0\n" is understood the same as the null |
|
564 string, meaning that both the IP address and host name are |
|
565 absent. If the client IP address is absent, then the IP |
|
566 address and host name are taken from the first non-local |
|
567 Received header if it has the standard "name (name [IP |
|
568 address])..." format. Non-standard Received headers com- |
|
569 monly added by qmail as well as Received headers specifying |
|
570 IP addresses marked <I>MX</I> or <I>MXDCC</I> in the global <B>-w</B> <I>whiteclnt</I> |
|
571 file are skipped. |
|
572 HELO SMTP HELO value or nothing, followed by a newline ('\n') |
|
573 character. If the HELO value is null and the IP address of |
|
574 the SMTP client are not supplied, they will be taken from |
|
575 the same Received: header that supplies the IP address. |
|
576 sender or SMTP <I>Mail</I> <I>From</I> command value for the env_from checksum. |
|
577 If the sender is null, the contents of the first Return- |
|
578 Path: or UNIX style From_ header is used. |
|
579 recipients or SMTP <I>Rcpt</I> <I>To</I> recipient mailboxes followed by correspond- |
|
580 ing local user names, one (mailbox,user) pair to a line. |
|
581 Each optional local user name is separated from the corre- |
|
582 sponding mailbox recipient address by a carriage return |
|
583 ('\r'). A local user name can be null if it is not known, |
|
584 but each recipient mailbox must be non-null. If there are |
|
585 no lines of (mailbox,user) pairs and if the <I>spam</I> option is |
|
586 not included, then the <I>query</I> is assumed. Mailboxes without |
|
587 user names will lack per-user log files and will not invoke |
|
588 a per-user whitelist. |
|
589 |
|
590 The last recipient-user name pair is followed by an empty line and the |
|
591 headers and body of the message. The end of the body of the mail message |
|
592 is signaled by the MTA half-closing the connection. See <B>shutdown(2)</B>. |
|
593 |
|
594 <B>Dccifd</B> responds with three things. First is a one character line of the |
|
595 overall result advising the MTA: |
|
596 A accept the message for all recipients and answer the SMTP DATA |
|
597 command with a 2yz result. |
|
598 G answer with a 4yz result to embargo the message for greylisting. |
|
599 R reject the message and answer the DATA command with a 5yz result. |
|
600 S accept the message for some recipients and so answer the DATA com- |
|
601 mand with a 2yz result. |
|
602 T temporary failure by the DCC system and so answer with a 4yz |
|
603 result. |
|
604 |
|
605 Second is a line of characters indicating the disposition of the message |
|
606 for each corresponding recipient: |
|
607 A deliver the message |
|
608 G discard the message during a greylist embargo |
|
609 R discard the message as spam |
|
610 The SMTP protocol allows only a single result for the DATA command for |
|
611 all recipients that were not rejected before body of the message was |
|
612 offered with the DATA command. To accept the message for some recipients |
|
613 and reject it for others, the MTA must tell the SMTP client it is accept- |
|
614 ing the message for all recipients and then discard it for those that |
|
615 would reject it. |
|
616 |
|
617 Finally, if the <I>body</I> or <I>header</I> strings are in the first line of <I>options</I> |
|
618 sent by the MTA to the daemon, then the <I>X-DCC</I> header line or the entire |
|
619 body with the <I>X-DCC</I> header line follows. |
|
620 |
|
621 |
|
622 </PRE> |
|
623 <H2><A NAME="FILES">FILES</A></H2><PRE> |
|
624 <A NAME="FILE-@prefix@">@prefix@</A> is the DCC home directory in which other files are found. |
|
625 <A NAME="FILE-@libexecdir@/start">@libexecdir@/start</A>-dccifd |
|
626 and |
|
627 <A NAME="FILE-@libexecdir@/rcDCC">@libexecdir@/rcDCC</A> |
|
628 are scripts used to start the daemon. |
|
629 <A NAME="FILE-dcc/dcc_conf">dcc/dcc_conf</A> |
|
630 contains parameters used by the scripts to start DCC daemons |
|
631 and cron jobs. |
|
632 <A NAME="FILE-logdir">logdir</A> is an optional directory specified with <B>-l</B> and containing |
|
633 marked mail. Each file in the directory contains one mes- |
|
634 sage, at least one of whose checksums reached its <B>-t</B> thresh- |
|
635 olds or that is interesting for some other reason. Each file |
|
636 starts with lines containing the date when the message was |
|
637 received, the IP address of the SMTP client, and SMTP enve- |
|
638 lope values. Those lines are followed by the body of the |
|
639 SMTP message including its header as it was received. Only |
|
640 approximately the first 32 KBytes of the body are recorded |
|
641 unless modified by <I>./configure</I> <I>--with-max-log-size=xx</I> The |
|
642 checksums for the message follow the body. They are followed |
|
643 by lines indicate that one of the checksums is white- or |
|
644 blacklisted by the <B>-w</B> <I>whiteclnt</I> file. Each log file ends |
|
645 with the <I>X-DCC</I> header line added to the message and the dis- |
|
646 position of the message. |
|
647 <A NAME="FILE-map">map</A> is the memory mapped file of information concerning DCC |
|
648 servers in the DCC home directory. |
|
649 <A NAME="FILE-whiteclnt">whiteclnt</A> contains the client whitelist in the format described in |
|
650 <B><A HREF="dcc.html">dcc(8)</A></B>. |
|
651 <A NAME="FILE-whiteclnt.dccw">whiteclnt.dccw</A> |
|
652 is a memory mapped hash table of the <I>whiteclnt</I> file. |
|
653 <A NAME="FILE-dccifd.pid">dccifd.pid</A> in the <B>-R</B> <I>rundir</I> directory contains daemon's process ID. |
|
654 |
|
655 |
|
656 </PRE> |
|
657 <H2><A NAME="EXAMPLES">EXAMPLES</A></H2><PRE> |
|
658 Dccifd can be used as Postfix Before-Queue Content filter. In some tests |
|
659 these values for <B>-p</B> and <B>-o</B> in <I>dcc</I><B>_</B><I>conf</I>. |
|
660 |
|
661 DCCIFD_ENABLE=on |
|
662 DCCIFD_ARGS="-p 127.0.0.1,10025,127.0.0.1/32 -o 127.0.0.1,10026 |
|
663 |
|
664 worked with these lines in /etc/postfix/master.cf |
|
665 |
|
666 smtp inet n - n - - smtpd |
|
667 -o smtpd_proxy_filter=127.0.0.1:10025 |
|
668 127.0.0.1:10026 inet n - n - - smtpd |
|
669 -o smtpd_authorized_xforward_hosts=127.0.0.0/8 |
|
670 -o smtpd_client_restrictions= |
|
671 -o smtpd_helo_restrictions= |
|
672 -o smtpd_sender_restrictions= |
|
673 -o smtpd_recipient_restrictions=permit_mynetworks,reject |
|
674 -o smtpd_data_restrictions= |
|
675 -o mynetworks=127.0.0.0/8 |
|
676 -o receive_override_options=no_unknown_recipient_checks |
|
677 |
|
678 |
|
679 </PRE> |
|
680 <H2><A NAME="SEE-ALSO">SEE ALSO</A></H2><PRE> |
|
681 <B><A HREF="cdcc.html">cdcc(8)</A></B>, <B><A HREF="dbclean.html">dbclean(8)</A></B>, <B><A HREF="dcc.html">dcc(8)</A></B>, <B><A HREF="dccd.html">dccd(8)</A></B>, <B><A HREF="dblist.html">dblist(8)</A></B>, <B><A HREF="dccm.html">dccm(8)</A></B>, <B><A HREF="dccproc.html">dccproc(8)</A></B>, |
|
682 <B><A HREF="dccsight.html">dccsight(8)</A></B>, |
|
683 |
|
684 |
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685 </PRE> |
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686 <H2><A NAME="HISTORY">HISTORY</A></H2><PRE> |
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687 Implementation of <B>dccifd</B> Distributed Checksum Clearinghouses are based on |
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688 an idea of Paul Vixie with code designed and written at Rhyolite Software |
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689 starting in 2000. was started at Rhyolite Software in 2002. This docu- |
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690 ment describes version 1.3.103. |
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691 |
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692 |
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693 </PRE> |
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694 <H2><A NAME="BUGS">BUGS</A></H2><PRE> |
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695 <B>dccifd</B> uses <B>-t</B> where <B><A HREF="dccproc.html">dccproc(8)</A></B> uses <B>-c</B>. |
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696 |
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697 By default <B>dccifd</B> look for its UNIX domain socket in the DCC home direc- |
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698 tory, but <B><A HREF="dccm.html">dccm(8)</A></B> looks in its <B>-R</B> <I>rundir</I>. |
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699 |
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700 Systems without <B>setrlimit(2)</B> and <B>getrlimit(2)</B> RLIMIT_NOFILE can have |
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701 problems with the default limit on the number of simultaneous jobs, the |
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702 value of <B>-j</B>. Every job requires four open files. These problems are |
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703 usually seen with errors messages that say something like |
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704 dccifd[24448]: DCC: accept(): Result too large |
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705 A fix is to use a smaller value for <B>-j</B> or to allow <B>dccifd</B> to open more |
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706 files. |
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707 |
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708 February 26, 2009 |
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709 </PRE> |
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710 <HR> |
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711 <ADDRESS> |
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712 Man(1) output converted with |
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713 <a href="http://www.oac.uci.edu/indiv/ehood/man2html.html">man2html</a> |
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714 modified for the DCC $Date 2001/04/29 03:22:18 $ |
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715 <BR> |
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716 <A HREF="http://www.dcc-servers.net/dcc/"> |
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717 <IMG SRC="http://logos.dcc-servers.net/border.png" |
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718 class=logo ALT="DCC logo"> |
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719 </A> |
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720 <A HREF="http://validator.w3.org/check?uri=referer"> |
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721 <IMG class=logo ALT="Valid HTML 4.01 Strict" |
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722 SRC="http://www.w3.org/Icons/valid-html401"> |
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723 </A> |
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726 </HTML> |