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5 <TITLE>dccm.0.8</TITLE> |
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11 </STYLE> |
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12 </HEAD> |
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13 <BODY> |
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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="dccm.html">dccm(8)</A></B> Distributed Checksum Clearinghouse <B><A HREF="dccm.html">dccm(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>dccm</B> -- Distributed Checksum Clearinghouse Milter Interface |
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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>dccm</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>protocol:filename</I> | <I>protocol:port@host</I>] [<B>-m</B> <I>map</I>] |
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28 [<B>-w</B> <I>whiteclnt</I>] [<B>-U</B> <I>userdirs</I>] [<B>-a</B> <I>IGNORE</I> | <I>REJECT</I> | <I>DISCARD</I>] |
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29 [<B>-t</B> <I>type,</I>[<I>log-thold,</I>]<I>rej-thold</I>] [<B>-g</B> [<I>not-</I>]<I>type</I>] [<B>-S</B> <I>header</I>] |
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30 [<B>-l</B> <I>logdir</I>] [<B>-R</B> <I>rundir</I>] [<B>-r</B> <I>rejection-msg</I>] [<B>-j</B> <I>maxjobs</I>] |
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31 [<B>-B</B> <I>dnsbl-option</I>] [<B>-L</B> <I>ltype,facility.level</I>] |
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32 |
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33 |
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34 </PRE> |
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35 <H2><A NAME="DESCRIPTION">DESCRIPTION</A></H2><PRE> |
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36 <B>dccm</B> is a daemon built with the sendmail milter interface intended to |
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37 connect <B>sendmail(8)</B> to DCC servers. When built with the milter filter |
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38 machinery and configured to talk to <B>dccm</B> in the <I>sendmail.cf</I> file, send- |
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39 mail passes all email to <B>dccm</B> which in turn reports related checksums to |
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40 the nearest DCC server. <B>dccm</B> then adds an <I>X-DCC</I> SMTP header line to the |
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41 message. Sendmail is told to reject the message if it is unsolicited |
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42 bulk mail. |
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43 |
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44 <B>Dccm</B> sends reports of checksums related to mail received by DCC clients |
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45 and queries about the total number of reports of particular checksums. A |
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46 DCC server receives <I>no</I> mail, address, headers, or other information, but |
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47 only cryptographically secure checksums of such information. A DCC |
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48 server cannot determine the text or other information that corresponds to |
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49 the checksums it receives. Its only acts as a clearinghouse of counts |
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50 for checksums computed by clients. For complete privacy as far as the |
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51 DCC is concerned, the checksums of purely internal mail or other mail |
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52 that is known to not be unsolicited bulk can be listed in a whitelist to |
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53 not be reported to the DCC server. |
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54 |
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55 Since the checksums of messages that are whitelisted locally by the <B>-w</B> |
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56 <I>whiteclnt</I> file are not reported to the DCC server, <B>dccm</B> knows nothing |
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57 about the total recipient counts for their checksums and so cannot add |
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58 <I>X-DCC</I> header lines to such messages. Sendmail does not tell <B>dccm</B> about |
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59 messages that are not received by sendmail via SMTP, including messages |
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60 submitted locally and received via UUCP, and so they also do not receive |
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61 <I>X-DCC</I> header lines. |
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62 |
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63 Enable the daemon and put its parameters in the <I>dcc</I><B>_</B><I>conf</I> file and start |
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64 the daemon with the <I>@libexecdir@/start-dccm</I> or <I>var/dcc/libexec/rcDCC</I> |
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65 script. |
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66 |
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67 The list of servers that <B>dccm</B> contacts is in the memory mapped file <I>map</I> |
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68 shared by local DCC clients. The file is maintained with <B><A HREF="cdcc.html">cdcc(8)</A></B>. |
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69 |
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70 <A NAME="OPTIONS"><B>OPTIONS</B></A> |
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71 The following options are available: |
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72 |
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73 <A NAME="OPTION-V"><B>-V</B></A> displays the version of <B>dccm</B>. |
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74 |
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75 <A NAME="OPTION-d"><B>-d</B></A> enables debugging output from the DCC client software. Additional |
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76 <B>-d</B> options increase the number of messages. A single <B>-d</B> |
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77 aborted SMTP transactions including those from some "dictionary |
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78 attacks." |
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79 |
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80 <A NAME="OPTION-b"><B>-b</B></A> causes the daemon to not detach itself from the controlling tty and |
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81 put itself into the background. |
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82 |
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83 <A NAME="OPTION-x"><B>-x</B></A> causes the daemon to try "extra hard" to contact a DCC server. |
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84 Since it is usually more important to deliver mail than to report |
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85 its checksums, <B>dccm</B> normally does not delay too long while trying to |
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86 contact a DCC server. It will not try again for several seconds |
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87 after a failure. With <B>-x</B>, it will always try to contact the DCC |
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88 server and it will tell the MTA to answer the DATA command with a |
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89 4yz temporary failure. |
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90 |
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91 <A NAME="OPTION-A"><B>-A</B></A> adds to existing X-DCC headers in the message instead of replacing |
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92 existing headers of the brand of the current server. |
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93 |
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94 <A NAME="OPTION-N"><B>-N</B></A> neither adds, deletes, nor replaces existing X-DCC headers in the |
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95 message. Each message is logged, rejected, and otherwise handled |
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96 the same. |
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97 |
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98 <A NAME="OPTION-Q"><B>-Q</B></A> only queries the DCC server about the checksums of messages instead |
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99 of reporting and querying. This is useful when <B>dccm</B> is used to fil- |
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100 ter mail that has already been reported to a DCC server by another |
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101 DCC client. No single mail message should be reported to a DCC |
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102 server more than once per recipient, because each report will |
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103 increase the apparent "bulkness" of the message. |
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104 |
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105 It is better to use <I>MXDCC</I> lines in the global <I>whiteclnt</I> file for |
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106 your MX mail servers that use DCC than <B>-Q</B>. |
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107 |
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108 <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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109 controls <I>greylisting</I>. At least one working greylist server must be |
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110 listed in the <I>map</I> file in the DCC home directory. If more than one |
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111 is named, they must "flood" or change checksums and they must use |
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112 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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113 DCC client processes use the same <B>-G</B> parameters. |
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114 |
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115 <I>IPmask/xx</I> and <I>noIP</I> remove part or all of the IP address from the |
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116 greylist triple. The CIDR block size, <I>xx</I>, must be between 1 and |
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117 128. 96 is added to block sizes smaller than 33 to make them appro- |
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118 priate for the IPv6 addresses used by the DCC. <I>IPmask/96</I> differs |
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119 from <I>noIP</I> for IPv4 addresses, because the former retains the IPv4 to |
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120 IPv6 mapping prefix. |
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121 |
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122 <A NAME="OPTION-h"><B>-h</B></A> <I>homedir</I> |
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123 overrides the default DCC home directory, <I>@prefix@</I>. |
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124 |
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125 <A NAME="OPTION-I"><B>-I</B></A> <I>user</I> |
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126 specifies the UID and GID of the process. |
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127 |
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128 <A NAME="OPTION-p"><B>-p</B></A> <I>protocol:filename</I> | <I>protocol:port@host</I> |
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129 specifies the protocol and address by which sendmail will contact |
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130 <B>dccm</B>. The default is a UNIX domain socket in the "run" directory, |
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131 <I>@dcc_rundir@/dccm</I>. (See also <B>-R)</B> This protocol and address must |
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132 match the value in <I>sendmail.cf</I>. This mechanism can be used to con- |
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133 nect <B>dccm</B> on one computer to sendmail on another computer when a |
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134 port and host name or IP address are used. |
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135 |
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136 <A NAME="OPTION-m"><B>-m</B></A> <I>map</I> |
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137 specifies a name or path of the memory mapped parameter file instead |
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138 of the default <I>map</I> file in the DCC home directory. It should be |
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139 created with the <B><A HREF="cdcc.html">cdcc(8)</A></B> command. |
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140 |
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141 <A NAME="OPTION-w"><B>-w</B></A> <I>whiteclnt</I> |
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142 specifies an optional file containing filtering parameters as well |
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143 as SMTP client IP addresses, SMTP envelope values, and header values |
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144 of mail that is spam or is not spam and does not need a <I>X-DCC</I> |
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145 header, and whose checksums should not be reported to the DCC |
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146 server. |
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147 |
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148 If the pathname <I>whiteclnt</I> is not absolute, it is relative to the DCC |
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149 home directory. |
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150 |
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151 The format of the <B>dccm</B> whiteclnt file is the same as the <I>whitelist</I> |
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152 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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153 See <B><A HREF="dcc.html">dcc(8)</A></B> for a description of DCC white and blacklists. Because |
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154 the contents of the <I>whiteclnt</I> file are used frequently, a companion |
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155 file is automatically created and maintained. It has the same path- |
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156 name but with an added suffix of <I>.dccw</I> and contains a memory mapped |
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157 hash table of the main file. |
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158 |
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159 A whitelist entry ("OK") or two or more semi-whitelistings ("OK2") |
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160 for one of the message's checksums prevents all of the message's |
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161 checksums from being reported to the DCC server and the addition of |
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162 a <I>X-DCC</I> header line by <B>dccm</B> A whitelist entry for a checksum also |
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163 prevents rejecting or discarding the message based on DCC recipient |
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164 counts as specified by <B>-a</B> and <B>-t</B>. Otherwise, one or more checksums |
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165 with blacklisting entries ("MANY") cause all of the message's check- |
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166 sums to be reported to the server with an addressee count of "MANY". |
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167 |
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168 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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169 "OK" for the checksum of its recipient address acts like any other |
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170 <I>whiteclnt</I> entry of "OK." When the SMTP message has more than one |
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171 recipient, the effects can be complicated. When a message has sev- |
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172 eral recipients with some but not all listed in the <I>whiteclnt</I> file, |
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173 <B>dccm</B> tries comply with the wishes of the users who want filtering as |
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174 well as those who don't by silently not delivering the message to |
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175 those who want filtering (i.e. are not whitelisted) and delivering |
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176 the message to don't want filtering. |
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177 |
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178 <A NAME="OPTION-U"><B>-U</B></A> <I>userdirs</I> |
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179 enables per-user <I>whiteclnt</I> files and log directories. Each target |
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180 of a message can have a directory of log files named |
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181 <I>usedirs/${dcc</I><B>_</B><I>userdir}/log</I> where <I>${dcc</I><B>_</B><I>userdir}</I> is the <I>sendmail.cf</I> |
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182 macro described below. If <I>${dcc</I><B>_</B><I>userdir}</I> is not set, |
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183 <I>userdirs/${rcpt</I><B>_</B><I>mailer}/${rcpt</I><B>_</B><I>addr}/log</I> is used. The most likely |
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184 value of <I>mailer</I> is <I>local</I>. Appropriate values for both |
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185 <I>${rcpt</I><B>_</B><I>mailer}</I> and <I>${rcpt</I><B>_</B><I>addr}</I> can be seen by examining <I>env</I><B>_</B><I>To</I> |
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186 lines in <B>-l</B> <I>logdir</I> files. If it is not absolute, <I>userdirs</I> is rela- |
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187 tive to the DCC home directory. The directory containing the log |
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188 files must be named <I>log</I> and it must be writable by the <B>dccm</B> process. |
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189 Each log directory must exist or logging for the corresponding is |
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190 silently disabled. The files created in the log directory are owned |
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191 by the UID of the <B>dccm</B> process, but they have <I>group</I> and <I>other</I> read |
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192 and write permissions copied from the corresponding <I>log</I> directory. |
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193 To ensure the privacy of mail, it may be good to make the directo- |
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194 ries readable only by <I>owner</I> and <I>group</I>, and to use a cron script that |
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195 changes the owner of each file to match the grandparent <I>addr</I> direc- |
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196 tory. |
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197 |
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198 There can also be a per -user whitelist file named |
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199 <I>userdirs/${dcc</I><B>_</B><I>userdir}/whiteclnt</I> or if <I>${dcc</I><B>_</B><I>userdir}</I> is not set, |
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200 <I>userdirs/${rcpt</I><B>_</B><I>mailer}/${rcpt</I><B>_</B><I>addr}</I> per-user whitelist files. Any |
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201 checksum that is not white- or blacklisted by an individual |
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202 addressee's <I>whiteclnt</I> file is checked in the main <B>-w -whiteclnt</B> |
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203 file. A missing per-addressee <I>whiteclnt</I> file is the same as an |
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204 empty file. Relative paths for files included in per-addressee |
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205 files are resolved in the DCC home directory. The <I>whiteclnt</I> files |
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206 and the <I>addr</I> directories containing them must be writable by the |
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207 <B>dccm</B> process. |
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208 |
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209 <I>Option</I> lines in per-user whiteclnt files can be used to modify many |
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210 aspects of <B>dccm</B> filtering, as described in the main dcc man page. |
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211 For example, an <I>option</I> <I>dcc-off</I> line turns off DCC filtering for |
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212 individual mailboxes. |
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213 |
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214 <A NAME="OPTION-a"><B>-a</B></A> <I>IGNORE</I> | <I>REJECT</I> | <I>DISCARD</I> |
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215 specifies the action taken when DCC server counts or <B>-t</B> thresholds |
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216 say that a message is unsolicited and bulk. <I>IGNORE</I> causes the mes- |
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217 sage to be unaffected except for adding the <I>X-DCC</I> header line to the |
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218 message. This turns off DCC filtering. |
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219 |
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220 Spam can also be <I>REJECT</I>ed or accepted and silently <I>DISCARD</I>ed without |
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221 being delivered to local mailboxes. The default is <I>REJECT</I>. |
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222 |
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223 Mail forwarded via IP addresses marked <I>MX</I> or <I>MXDCC</I> in the main |
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224 <I>whiteclnt</I> file is treated as if <B>-a</B> <I>DISCARD</I> were specified. This |
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225 prevents "bouncing" spam. |
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226 |
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227 Determinations that mail is or is not spam from sendmail via |
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228 <I>${dcc</I><B>_</B><I>isspam}</I> or <I>${dcc</I><B>_</B><I>notspam}</I> macros override <B>-a</B>. The effects of |
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229 the <B>-w</B> <I>whiteclnt</I> are not affected by <B>-a</B>. |
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230 |
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231 <A NAME="OPTION-t"><B>-t</B></A> <I>type,</I>[<I>log-thold,</I>]<I>rej-thold</I> |
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232 sets logging and "spam" thresholds for checksum <I>type</I>. The checksum |
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233 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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234 <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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235 <I>substitute</I>, have no effect except when a local DCC server configured |
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236 with <B>-K</B> is used. The <I>substitute</I> thresholds apply to the first sub- |
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237 stitute heading encountered in the mail message. The string <I>ALL</I> |
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238 sets thresholds for all types, but is unlikely to be useful except |
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239 for setting logging thresholds. The string <I>CMN</I> specifies the com- |
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240 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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241 must be numbers, the string <I>NEVER</I>, or the string <I>MANY</I> indicating |
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242 millions of targets. Counts from the DCC server as large as the |
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243 threshold for any single type are taken as sufficient evidence that |
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244 the message should be logged or rejected. |
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245 |
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246 <I>Log-thold</I> is the threshold at which messages are logged. It can be |
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247 handy to log messages at a lower threshold to find solicited bulk |
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248 mail sources such as mailing lists. If no logging threshold is set, |
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249 only rejected mail and messages with complicated combinations of |
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250 white and blacklisting are logged. Messages that reach at least one |
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251 of their rejection thresholds are logged regardless of logging |
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252 thresholds. |
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253 |
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254 <I>Rej-thold</I> is the threshold at which messages are considered "bulk," |
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255 and so should be rejected or discarded if not whitelisted. |
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256 |
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257 DCC Reputation thresholds in the commercial version of the DCC are |
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258 controlled by thresholds on checksum types <I>rep</I> and <I>rep-total</I>. Mes- |
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259 sages from an IP address that the DCC database says has sent more |
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260 than <B>-t</B> <I>rep-total,log-thold</I> messages are logged. A DCC Reputation |
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261 is computed for messages received from IP addresses that have sent |
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262 more than <B>-t</B> <I>rep-total,log-thold</I> messages. The DCC Reputation of an |
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263 IP address is the percentage of its messages that have been detected |
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264 as bulk or having at least 10 recipients. The defaults are equiva- |
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265 lent to <B>-t</B> <I>rep,never</I> and <B>-t</B> <I>rep-total,never,20</I>. |
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266 |
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267 Bad DCC Reputations do not reject mail unless enabled by an <I>option</I> |
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268 <I>DCC-rep-on</I> line in a <I>whiteclnt</I> file. |
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269 |
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270 The checksums of locally whitelisted messages are not checked with |
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271 the DCC server and so only the number of targets of the current copy |
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272 of a whitelisted message are compared against the thresholds. |
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273 |
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274 The default is <I>ALL,NEVER</I>, so that nothing is discarded, rejected, or |
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275 logged. A common choice is <I>CMN,25,50</I> to reject or discard mail with |
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276 common bodies except as overridden by the whitelist of the DCC |
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277 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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278 <B>-g</B>, and <B>-w</B>. |
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279 |
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280 <A NAME="OPTION-g"><B>-g</B></A> [<I>not-</I>]<I>type</I> |
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281 indicates that whitelisted, <I>OK</I> or <I>OK2</I>, counts from the DCC server |
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282 for a type of checksum are to be believed. They should be ignored |
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283 if prefixed with <I>not-</I>. <I>Type</I> is one of the same set of strings as |
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284 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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285 all three are honored, and hence the need for <I>not-</I>. |
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286 |
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287 <A NAME="OPTION-S"><B>-S</B></A> <I>hdr</I> |
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288 adds to the list of substitute or locally chosen headers that are |
|
|
289 checked with the <B>-w</B> <I>whiteclnt</I> file and sent to the DCC server. The |
|
|
290 checksum of the last header of type <I>hdr</I> found in the message is |
|
|
291 checked. <I>Hdr</I> can be <I>HELO</I> to specify the SMTP envelope HELO value. |
|
|
292 <I>Hdr</I> can also be <I>mail</I><B>_</B><I>host</I> to specify the sendmail "resolved" host |
|
|
293 name from the Mail_from value in the SMTP envelope. As many as six |
|
|
294 different substitute headers can be specified, but only the checksum |
|
|
295 of the first of the six will be sent to the DCC server. |
|
|
296 |
|
|
297 <A NAME="OPTION-l"><B>-l</B></A> <I>logdir</I> |
|
|
298 specifies a directory in which files containing copies of messages |
|
|
299 processed by <B>dccm</B> are kept. They can be copied to per-user directo- |
|
|
300 ries specified with <B>-U</B>. Information about other recipients of a |
|
|
301 message is deleted from the per-user copies. |
|
|
302 |
|
|
303 See the FILES section below concerning the contents of the files. |
|
|
304 See also the <I>option</I> <I>log-subdirectory-{day,hour,minute}</I> lines in |
|
|
305 <I>whiteclnt</I> files described in <B><A HREF="dcc.html">dcc(8)</A></B>. |
|
|
306 |
|
|
307 The directory is relative to the DCC home directory if it is not |
|
|
308 absolute |
|
|
309 |
|
|
310 <A NAME="OPTION-R"><B>-R</B></A> <I>rundir</I> |
|
|
311 specifies the "run" directory where the UNIX domain socket and file |
|
|
312 containing the daemon's process ID are stored. The default value is |
|
|
313 @dcc_rundir@ . |
|
|
314 |
|
|
315 <A NAME="OPTION-r"><B>-r</B></A> <I>rejection-msg</I> |
|
|
316 specifies the rejection message in <B>-o</B> proxy mode for unsolicited |
|
|
317 bulk mail or for mail temporarily blocked by <I>greylisting</I> when <B>-G</B> is |
|
|
318 specified. The first <B>-r</B> <I>rejection-msg</I> replaces the default bulk |
|
|
319 mail rejection message, "5.7.1 550 mail %ID from %CIP rejected by |
|
|
320 DCC". The second replaces "4.2.1 452 mail %ID from %CIP temporary |
|
|
321 greylist embargoed". The third <B>-r</B> <I>rejection-msg</I> replaces the |
|
|
322 default SMTP rejection message "5.7.1 550 %ID bad reputation; see |
|
|
323 http://commercial-dcc.rhyolite.com/cgi-bin/reps.cgi?tgt=%CIP" for |
|
|
324 mail with bad DCC Reputations. If <I>rejection-msg</I> is the zero-length |
|
|
325 string, the <B>-r</B> setting is counted but the corresponding message is |
|
|
326 not changed. |
|
|
327 |
|
|
328 <I>Rejection-msg</I> can contain specific information about the mail mes- |
|
|
329 sage. The following strings starting with % are replaced with the |
|
|
330 corresponding values: |
|
|
331 %ID message ID such as the unique part of log file name or |
|
|
332 sendmail queue ID |
|
|
333 %CIP SMTP client IP address |
|
|
334 %BTYPE type of DNS blacklist hit, such as "SMTP client", |
|
|
335 "mail_host", or "URL NS" |
|
|
336 %BTGT IP address or name declared bad by DNS blacklist |
|
|
337 %BPROBE domain name found in DNS blacklist such as |
|
|
338 4.3.2.10.example.com |
|
|
339 %BRESULT value of the %BPROBE domain name found in DNS black- |
|
|
340 list |
|
|
341 |
|
|
342 A common alternate for the bulk mail rejection message is "4.7.1 451 |
|
|
343 Access denied by DCC" to tell the sending mail system to continue |
|
|
344 trying. Use a 4yz response with caution, because it is likely to |
|
|
345 delay for days a delivery failure message for false positives. If |
|
|
346 the rejection message does not start with an RFC 1893 status code |
|
|
347 and RFC 2821 reply code, 5.7.1 and 550 or 4.2.1 and 452 are used. |
|
|
348 |
|
|
349 See also <B>-B</B> <I>set:rej-msg=rejection-msg</I> to set the status message for |
|
|
350 mail rejected by DNS blacklists. |
|
|
351 |
|
|
352 <A NAME="OPTION-j"><B>-j</B></A> <I>maxjobs</I> |
|
|
353 limits the number of simultaneous requests that will be processed. |
|
|
354 The default value is the maximum number that seems to be possible |
|
|
355 given system limits on open files, select() bit masks, and so forth. |
|
|
356 Start <B>dccm</B> with <B>-d</B> and see the starting message in the system log to |
|
|
357 see the limit. |
|
|
358 |
|
|
359 <A NAME="OPTION-B"><B>-B</B></A> <I>dnsbl-option</I> |
|
|
360 enables DNS blacklist checks of the SMTP client IP address, SMTP |
|
|
361 envelope Mail_From sender domain name, and of host names in URLs in |
|
|
362 the message body. Body URL blacklisting has too many false posi- |
|
|
363 tives to use on abuse mailboxes. It is less effective than |
|
|
364 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- |
|
|
365 tions where greylisting cannot be used. |
|
|
366 |
|
|
367 <I>Dnsbl-option</I> is either one of the <B>-B</B> <I>set:option</I> forms or |
|
|
368 <B>-B</B> <I>domain</I>[<I>,IPaddr</I>[<I>/xx</I>[<I>,bltype</I>]]] |
|
|
369 <I>Domain</I> is a DNS blacklist domain such as example.com that will be |
|
|
370 searched. <I>IPaddr</I>[<I>/xxx</I>] is the string "any" an IP address in the DNS |
|
|
371 blacklist that indicates that the mail message should be rejected, |
|
|
372 or a CIDR block covering results from the DNS blacklist. |
|
|
373 "127.0.0.2" is assumed if <I>IPaddr</I> is absent. IPv6 addresses can be |
|
|
374 specified with the usual colon (:) notation. Names can be used |
|
|
375 instead of numeric addresses. The type of DNS blacklist is speci- |
|
|
376 fied by <I>bltype</I> as <I>name</I>, <I>IPv4</I>, or <I>IPv6</I>. Given an envelope sender |
|
|
377 domain name or a domain name in a URL of spam.domain.org and a |
|
|
378 blacklist of type <I>name</I>, spam.domain.org.example.com will be tried. |
|
|
379 Blacklist types of <I>IPv4</I> and <I>IPv6</I> require that the domain name in a |
|
|
380 URL sender address be resolved into an IPv4 or IPv6 address. The |
|
|
381 address is then written as a reversed string of decimal octets to |
|
|
382 check the DNS blacklist, as in 2.0.0.127.example.com, |
|
|
383 |
|
|
384 More than one blacklist can be specified and blacklists can be |
|
|
385 grouped. All searching within a group is stopped at the first posi- |
|
|
386 tive result. |
|
|
387 |
|
|
388 Positive results are ignored after being logged unless an |
|
|
389 <I>option</I> <I>DNSBL-on</I> line appears in the global or per-user <I>whiteclnt</I> |
|
|
390 file. |
|
|
391 |
|
|
392 <B>-B</B> <I>set:no-client</I> |
|
|
393 says that SMTP client IP addresses and reverse DNS domain names |
|
|
394 should not be checked in the following blacklists. |
|
|
395 <B>-B</B> <I>set:client</I> restores the default for the following black- |
|
|
396 lists. |
|
|
397 |
|
|
398 <B>-B</B> <I>set:no-mail</I><B>_</B><I>host</I> |
|
|
399 says that SMTP envelope Mail_From sender domain names should |
|
|
400 not be checked in the following blacklists. <B>-B</B> <I>set:mail</I><B>_</B><I>host</I> |
|
|
401 restores the default. |
|
|
402 |
|
|
403 <B>-B</B> <I>set:no-URL</I> |
|
|
404 says that URLs in the message body should not be checked in the |
|
|
405 in the following blacklists. <B>-B</B> <I>set:URL</I> restores the default. |
|
|
406 |
|
|
407 <B>-B</B> <I>set:no-MX</I> |
|
|
408 says MX servers of sender Mail_From domain names and host names |
|
|
409 in URLs should not be checked in the following blacklists. |
|
|
410 <B>-B</B> <I>set:MX</I> restores the default. |
|
|
411 |
|
|
412 <B>-B</B> <I>set:no-NS</I> |
|
|
413 says DNS servers of sender Mail_From domain names and host |
|
|
414 names in URLs should not be checked in the following black- |
|
|
415 lists. <B>-B</B> <I>set:NS</I> restores the default. |
|
|
416 |
|
|
417 <B>-B</B> <I>set:defaults</I> |
|
|
418 is equivalent to all of <B>-B</B> <I>set:no-temp-fail</I> <B>-B</B> <I>set:client</I> |
|
|
419 <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> |
|
|
420 |
|
|
421 <B>-B</B> <I>set:group=X</I> |
|
|
422 adds later DNS blacklists specified with |
|
|
423 <B>-B</B> <I>domain</I>[<I>,IPaddr</I>[<I>/xx</I>[<I>,bltype</I>]]] |
|
|
424 to group 1, 2, or 3. |
|
|
425 |
|
|
426 <B>-B</B> <I>set:debug=X</I> |
|
|
427 sets the DNS blacklist logging level |
|
|
428 |
|
|
429 <B>-B</B> <I>set:msg-secs=S</I> |
|
|
430 limits <B>dccm</B> to <I>S</I> seconds total for checking all DNS blacklists. |
|
|
431 The default is 25. |
|
|
432 |
|
|
433 <B>-B</B> <I>set:URL-secs=S</I> |
|
|
434 limits <B>dccm</B> to at most <I>S</I> seconds resolving and checking any |
|
|
435 single URL. The default is 11. Some spam contains dozens of |
|
|
436 URLs and that some "spamvertised" URLs contain host names that |
|
|
437 need minutes to resolve. Busy mail systems cannot afford to |
|
|
438 spend minutes checking each incoming mail message. |
|
|
439 |
|
|
440 <B>-B</B> <I>set:rej-msg=rejection-msg</I> |
|
|
441 sets the SMTP rejection message for the following blacklists. |
|
|
442 <I>Rejection-msg</I> must be in the same format as for <B>-r</B>. If |
|
|
443 <I>rejection-msg</I> is null, the default is restored. The default |
|
|
444 DNS blacklist rejection message is the first message set with |
|
|
445 <B>-r</B>. |
|
|
446 |
|
|
447 <B>-B</B> <I>set:temp-fail</I> |
|
|
448 causes <B>dccm</B> to the MTA to answer the SMTP DATA command with |
|
|
449 452 4.2.1 mail %ID from %CIP temporary delayed for DNSBL |
|
|
450 if any DNS answer required for a DNSBL in the current group |
|
|
451 times out, including resolving names in URLs. |
|
|
452 |
|
|
453 <B>-B</B> <I>set:no-temp-fail</I> |
|
|
454 restores the default of assuming a negative answer for DNS |
|
|
455 responses that take too long. |
|
|
456 |
|
|
457 <B>-B</B> <I>set:maxjobs=X</I> |
|
|
458 sets maximum number of helper processes to <I>X</I>. In order to use |
|
|
459 typical single-threaded DNS resolver libraries, <B>dccm</B> uses |
|
|
460 fleets of helper processes. It is rarely a good idea to change |
|
|
461 the default, which is the same as the maximum number of simul- |
|
|
462 taneous jobs set with <B>-j</B>. |
|
|
463 |
|
|
464 <B>-B</B> <I>set:progpath=@libexecdir@/dns-helper</I> |
|
|
465 changes the path to the helper program. |
|
|
466 |
|
|
467 <A NAME="OPTION-L"><B>-L</B></A> <I>ltype,facility.level</I> |
|
|
468 specifies how messages should be logged. <I>Ltype</I> must be <I>error</I>, <I>info</I>, |
|
|
469 or <I>off</I> to indicate which of the two types of messages are being con- |
|
|
470 trolled or to turn off all <B>syslog(3)</B> messages from <B>dccm</B>. <I>Level</I> must |
|
|
471 be a <B>syslog(3)</B> level among <I>EMERG</I>, <I>ALERT</I>, <I>CRIT</I>, <I>ERR</I>, <I>WARNING</I>, <I>NOTICE</I>, |
|
|
472 <I>INFO</I>, and <I>DEBUG</I>. <I>Facility</I> must be among <I>AUTH</I>, <I>AUTHPRIV</I>, <I>CRON</I>, |
|
|
473 <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> through |
|
|
474 <I>LOCAL7</I>. The default is equivalent to |
|
|
475 <B>-L</B> <I>info,MAIL.NOTICE</I> <B>-L</B> <I>error,MAIL.ERR</I> |
|
|
476 |
|
|
477 <B>dccm</B> normally sends counts of mail rejected and so forth the to system |
|
|
478 log at midnight. The SIGUSR1 signal sends an immediate report to the |
|
|
479 system log. They will be repeated every 24 hours instead of at midnight. |
|
|
480 |
|
|
481 |
|
|
482 </PRE> |
|
|
483 <H2><A NAME="SENDMAIL-MACROS">SENDMAIL MACROS</A></H2><PRE> |
|
|
484 Sendmail can affect <B>dccm</B> with the values of some <I>sendmail.cf</I> macros. |
|
|
485 These macro names must be added to the Milter.macros option statements in |
|
|
486 <I>sendmail.cf</I> as in the example "Feature" file dcc.m4. |
|
|
487 |
|
|
488 <I>${dcc</I><B>_</B><I>isspam}</I> causes a mail message to be reported to the DCC server as |
|
|
489 having been addressed to "MANY" recipients. The |
|
|
490 <I>${dcc</I><B>_</B><I>isspam}</I> macro is ignored if the <I>${dcc</I><B>_</B><I>notspam}</I> macro |
|
|
491 is set to a non-null string |
|
|
492 |
|
|
493 If the value of the <I>${dcc</I><B>_</B><I>isspam}</I> is null, <B>dccm</B> uses SMTP |
|
|
494 rejection messages controlled by <B>-a</B> and <B>-r</B>. If the value |
|
|
495 of the <I>${dcc</I><B>_</B><I>isspam}</I> macro starts with "DISCARD", the mail |
|
|
496 message is silently discarded as with <B>-a</B> <I>DISCARD.</I> If value |
|
|
497 of the macro not null and does not start with "DISCARD", |
|
|
498 it is used as the SMTP error message given to the SMTP |
|
|
499 client trying to send the rejected message. The message |
|
|
500 starts with an optional SMTP error type and number fol- |
|
|
501 lowed by text. |
|
|
502 |
|
|
503 The <B>-a</B> option does not effect messages marked spam with |
|
|
504 <I>${dcc</I><B>_</B><I>isspam}</I>. When the <I>${dcc</I><B>_</B><I>isspam}</I> macro is set, the |
|
|
505 message is rejected or discarded despite local or DCC |
|
|
506 database whitelist entries. The local whitelist does con- |
|
|
507 trol whether the message's checksums will be reported to |
|
|
508 the DCC server and an <I>X-DCC</I> SMTP header line will be |
|
|
509 added. |
|
|
510 |
|
|
511 <I>${dcc</I><B>_</B><I>notspam}</I> |
|
|
512 causes a message not be considered unsolicited bulk |
|
|
513 despite evidence to the contrary. It also prevents <B>dccm</B> |
|
|
514 from reporting the checksums of the message to the DCC |
|
|
515 server and from adding an <I>X-DCC</I> header line. |
|
|
516 |
|
|
517 When the macro is set by the <I>sendmail.cf</I> rules, |
|
|
518 <I>${dcc</I><B>_</B><I>notspam}</I> macros overrides DCC threshlds that say the |
|
|
519 message should be rejected as well as the effects of the |
|
|
520 <I>${dcc</I><B>_</B><I>isspam}</I> macro. |
|
|
521 |
|
|
522 <I>${dcc</I><B>_</B><I>mail</I><B>_</B><I>host}</I> |
|
|
523 specifies the name of the SMTP client that is sending the |
|
|
524 message. This macro is usually the same as the <I>mail</I><B>_</B><I>host</I> |
|
|
525 macro. They can differ when a sendmail "smart relay" is |
|
|
526 involved. The <I>${dcc</I><B>_</B><I>mail</I><B>_</B><I>host}</I> macro does not work if |
|
|
527 <I>FEATURE(delay</I><B>_</B><I>checks)</I> is used. |
|
|
528 |
|
|
529 <I>${dcc</I><B>_</B><I>userdir}</I> |
|
|
530 is the per-user whitelist and log directory for a recipi- |
|
|
531 ent. If the macro is not set in sendmail.cf, |
|
|
532 $&{rcpt_mailer}/$&{rcpt_addr} is assumed, but with the |
|
|
533 recipient address converted to lower case. Whatever value |
|
|
534 is used, the directory name after the last slash (/) char- |
|
|
535 acter is converted to lower case. Any value containing |
|
|
536 the string "/../" is ignored. |
|
|
537 |
|
|
538 This macro also does not work if <I>FEATURE(delay</I><B>_</B><I>checks)</I> is |
|
|
539 used. |
|
|
540 |
|
|
541 The following two lines in a sendmail mc file have the |
|
|
542 same effect as not defining the ${dcc_userdir} macro, pro- |
|
|
543 vided <I>FEATURE(dcc)</I> is also used and the sendmail |
|
|
544 <I>cf/feature</I> directory has a symbolic link to the |
|
|
545 <I>misc/dcc.m4</I> file. |
|
|
546 |
|
|
547 SLocal_check_rcpt |
|
|
548 R$* $: $1 $(macro {dcc_userdir} $@ $&{rcpt_mailer}/$&{rcpt_addr} $)) |
|
|
549 |
|
|
550 |
|
|
551 </PRE> |
|
|
552 <H2><A NAME="FILES">FILES</A></H2><PRE> |
|
|
553 <A NAME="FILE-@prefix@">@prefix@</A> is the DCC home directory in which other files are found. |
|
|
554 <A NAME="FILE-@libexecdir@/start">@libexecdir@/start</A>-dccm |
|
|
555 is a script used to <B>dccm</B>. |
|
|
556 <A NAME="FILE-dcc/dcc_conf">dcc/dcc_conf</A> |
|
|
557 contains parameters used by the scripts to start DCC daemons |
|
|
558 and cron jobs. |
|
|
559 <A NAME="FILE-logdir">logdir</A> is an optional directory specified with <B>-l</B> and containing |
|
|
560 marked mail. Each file in the directory contains one message, |
|
|
561 at least one of whose checksums reached its <B>-t</B> thresholds or |
|
|
562 that is interesting for some other reason. Each file starts |
|
|
563 with lines containing the date when the message was received, |
|
|
564 the IP address of the SMTP client, and SMTP envelope values. |
|
|
565 Those lines are followed by the body of the SMTP message |
|
|
566 including its header as it was received by sendmail and with- |
|
|
567 out any new or changed header lines. Only approximately the |
|
|
568 first 32 KBytes of the body are recorded unless modified by |
|
|
569 <I>./configure</I> <I>--with-max-log-size=xx</I> The checksums for the mes- |
|
|
570 sage follow the body. They are followed by lines indicating |
|
|
571 that the <I>${dcc</I><B>_</B><I>isspam}</I> or <I>${dcc</I><B>_</B><I>notspam}</I> <I>sendmail.cf</I> macros |
|
|
572 were set or one of the checksums is white- or blacklisted by |
|
|
573 the <B>-w</B> <I>whiteclnt</I> file. Each file ends with the <I>X-DCC</I> header |
|
|
574 line added to the message and the disposition of the message |
|
|
575 including SMTP status message if appropriate. |
|
|
576 <A NAME="FILE-map">map</A> is the memory mapped file of information concerning DCC |
|
|
577 servers in the DCC home directory. |
|
|
578 <A NAME="FILE-whiteclnt">whiteclnt</A> contains the client whitelist in the format described in |
|
|
579 <B><A HREF="dcc.html">dcc(8)</A></B>. |
|
|
580 <A NAME="FILE-whiteclnt.dccw">whiteclnt.dccw</A> |
|
|
581 is a memory mapped hash table of the <I>whiteclnt</I> file. |
|
|
582 <A NAME="FILE-dccm.pid">dccm.pid</A> in the <B>-R</B> <I>rundir</I> directory contains daemon's process ID. The |
|
|
583 string ``dccm'' is replaced by the file name containing the |
|
|
584 daemon to facilitate running multiple daemons, probably con- |
|
|
585 nected to remote instances of sendmail using TCP/IP instead of |
|
|
586 a UNIX domain socket. See also <B>-R</B>. |
|
|
587 <A NAME="FILE-@dcc_rundir@/dccm">@dcc_rundir@/dccm</A> |
|
|
588 is the default UNIX domain socket used by the sendmail milter |
|
|
589 interface. See also <B>-R</B>. |
|
|
590 <A NAME="FILE-sendmail.cf">sendmail.cf</A> |
|
|
591 is the <B>sendmail(8)</B> control file. |
|
|
592 <A NAME="FILE-misc/dcc.m4">misc/dcc.m4</A> |
|
|
593 sendmail mc file that should have a symbolic link in the send- |
|
|
594 mail cf/feature directory so that <I>FEATURE(dcc)</I> can be used in |
|
|
595 a sendmail mc file. |
|
|
596 |
|
|
597 |
|
|
598 </PRE> |
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599 <H2><A NAME="EXAMPLES">EXAMPLES</A></H2><PRE> |
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600 <B>Dccm</B> should be started before sendmail with something like the script |
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601 <I>@libexecdir@/start-dccm.</I> It looks for common DCC parameters in the |
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602 <I>dcc</I><B>_</B><I>conf</I> file in the DCC home directory, <I>@prefix@.</I> |
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603 |
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604 Those numbers should modified to fit local conditions. It might be wise |
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605 to replace the "100" numbers with much larger values or with "MANY" until |
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606 a few weeks of monitoring the log directory show that sources of mailing |
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607 lists are in the server's whitelist file (see <B><A HREF="dccd.html">dccd(8)</A></B>) or the local |
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608 <I>whiteclnt</I> file. |
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609 |
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610 It is usually necessary to regularly delete old log files with a script |
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611 like @libexecdir@/cron-dccd. |
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612 |
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613 On systems unlike modern FreeBSD and other UNIX-like systems which |
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614 include sendmail milter support, sendmail must be built with the milter |
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615 interface, such as by creating a <I>devtools/Site/site.config.m4</I> or similar |
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616 file containing something like the following lines: |
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617 |
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618 APPENDDEF(`conf_sendmail_ENVDEF', `-D_FFR_MILTER=1') |
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619 APPENDDEF(`conf_libmilter_ENVDEF', `-D_FFR_MILTER=1') |
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620 |
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621 Appropriate lines invoking the milter interface must be added to |
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622 <I>sendmail.cf.</I> That can be done by putting a symbolic link to the the |
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623 misc/dcc.m4 file in the DCC source to the sendmail cf/feature directory |
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624 and adding the line |
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625 |
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626 FEATURE(dcc) |
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627 |
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628 to the local .mc file. |
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629 |
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630 Note that <B>dccm</B> should not be used with the Postfix milter mechanism. |
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631 Instead use <B><A HREF="dccifd.html">dccifd(8)</A></B> as a before-queue filter as described in that man |
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632 page. |
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633 |
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634 |
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635 </PRE> |
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636 <H2><A NAME="SEE-ALSO">SEE ALSO</A></H2><PRE> |
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637 <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="dccifd.html">dccifd(8)</A></B>, <B><A HREF="dccproc.html">dccproc(8)</A></B>, |
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638 <B><A HREF="dccsight.html">dccsight(8)</A></B>, <B>sendmail(8)</B>. |
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639 |
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640 |
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641 </PRE> |
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642 <H2><A NAME="HISTORY">HISTORY</A></H2><PRE> |
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643 Distributed Checksum Clearinghouses are based on an idea of Paul Vixie. |
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644 Implementation of <B>dccm</B> was started at Rhyolite Software in 2000. This |
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645 document describes version 1.3.103. |
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646 |
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647 |
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648 </PRE> |
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649 <H2><A NAME="BUGS">BUGS</A></H2><PRE> |
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650 <B>dccm</B> uses <B>-t</B> where <B><A HREF="dccproc.html">dccproc(8)</A></B> uses <B>-c</B>. |
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651 |
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652 Systems without <B>setrlimit(2)</B> and <B>getrlimit(2)</B> RLIMIT_NOFILE can have |
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653 problems with the default limit on the number of simultaneous jobs, the |
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654 value of <B>-j</B>. Every job requires four open files. These problems are |
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655 usually seen with errors messages that say something like |
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656 dccm[24448]: DCC: accept() returned invalid socket |
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657 A fix is to use a smaller value for <B>-j</B> or to allow <B>dccm</B> to open more |
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658 files. Sendmail version 8.13 and later can be told to poll() instead of |
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659 select with SM_CONF_POLL. Some older versions of sendmail knew about |
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660 FFR_USE_POLL. One of the following lines in your devtools/Site/site.con- |
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661 fig.m4 file can help: |
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662 |
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663 APPENDDEF(`conf_libmilter_ENVDEF', `-DSM_CONF_POLL') |
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664 APPENDDEF(`conf_libmilter_ENVDEF', `-DFFR_USE_POLL') |
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665 |
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666 On many systems with sendmail 8.11.3 and preceding, a bug in the sendmail |
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667 milter mechanism causes <B>dccm</B> to die with a core file when given a signal. |
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668 |
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669 February 26, 2009 |
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670 </PRE> |
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671 <HR> |
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672 <ADDRESS> |
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673 Man(1) output converted with |
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674 <a href="http://www.oac.uci.edu/indiv/ehood/man2html.html">man2html</a> |
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675 modified for the DCC $Date 2001/04/29 03:22:18 $ |
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676 <BR> |
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677 <A HREF="http://www.dcc-servers.net/dcc/"> |
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678 <IMG SRC="http://logos.dcc-servers.net/border.png" |
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679 class=logo ALT="DCC logo"> |
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680 </A> |
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681 <A HREF="http://validator.w3.org/check?uri=referer"> |
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682 <IMG class=logo ALT="Valid HTML 4.01 Strict" |
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683 SRC="http://www.w3.org/Icons/valid-html401"> |
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684 </A> |
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685 </ADDRESS> |
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686 </BODY> |
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687 </HTML> |
