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1 dccm(8) Distributed Checksum Clearinghouse dccm(8) |
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2 |
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3 NNAAMMEE |
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4 ddccccmm -- Distributed Checksum Clearinghouse Milter Interface |
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5 |
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6 SSYYNNOOPPSSIISS |
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7 ddccccmm [--VVddbbxxAANNQQ] [--GG _o_n | _o_f_f | _n_o_I_P | _I_P_m_a_s_k_/_x_x] [--hh _h_o_m_e_d_i_r] [--II _u_s_e_r] |
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8 [--pp _p_r_o_t_o_c_o_l_:_f_i_l_e_n_a_m_e | _p_r_o_t_o_c_o_l_:_p_o_r_t_@_h_o_s_t] [--mm _m_a_p] |
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9 [--ww _w_h_i_t_e_c_l_n_t] [--UU _u_s_e_r_d_i_r_s] [--aa _I_G_N_O_R_E | _R_E_J_E_C_T | _D_I_S_C_A_R_D] |
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10 [--tt _t_y_p_e_,[_l_o_g_-_t_h_o_l_d_,]_r_e_j_-_t_h_o_l_d] [--gg [_n_o_t_-]_t_y_p_e] [--SS _h_e_a_d_e_r] |
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11 [--ll _l_o_g_d_i_r] [--RR _r_u_n_d_i_r] [--rr _r_e_j_e_c_t_i_o_n_-_m_s_g] [--jj _m_a_x_j_o_b_s] |
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12 [--BB _d_n_s_b_l_-_o_p_t_i_o_n] [--LL _l_t_y_p_e_,_f_a_c_i_l_i_t_y_._l_e_v_e_l] |
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13 |
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14 DDEESSCCRRIIPPTTIIOONN |
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15 ddccccmm is a daemon built with the sendmail milter interface intended to |
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16 connect sendmail(8) to DCC servers. When built with the milter filter |
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17 machinery and configured to talk to ddccccmm in the _s_e_n_d_m_a_i_l_._c_f file, send- |
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18 mail passes all email to ddccccmm which in turn reports related checksums to |
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19 the nearest DCC server. ddccccmm then adds an _X_-_D_C_C SMTP header line to the |
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20 message. Sendmail is told to reject the message if it is unsolicited |
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21 bulk mail. |
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22 |
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23 DDccccmm sends reports of checksums related to mail received by DCC clients |
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24 and queries about the total number of reports of particular checksums. A |
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25 DCC server receives _n_o mail, address, headers, or other information, but |
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26 only cryptographically secure checksums of such information. A DCC |
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27 server cannot determine the text or other information that corresponds to |
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28 the checksums it receives. Its only acts as a clearinghouse of counts |
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29 for checksums computed by clients. For complete privacy as far as the |
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30 DCC is concerned, the checksums of purely internal mail or other mail |
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31 that is known to not be unsolicited bulk can be listed in a whitelist to |
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32 not be reported to the DCC server. |
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33 |
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34 Since the checksums of messages that are whitelisted locally by the --ww |
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35 _w_h_i_t_e_c_l_n_t file are not reported to the DCC server, ddccccmm knows nothing |
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36 about the total recipient counts for their checksums and so cannot add |
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37 _X_-_D_C_C header lines to such messages. Sendmail does not tell ddccccmm about |
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38 messages that are not received by sendmail via SMTP, including messages |
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39 submitted locally and received via UUCP, and so they also do not receive |
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40 _X_-_D_C_C header lines. |
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41 |
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42 Enable the daemon and put its parameters in the _d_c_c___c_o_n_f file and start |
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43 the daemon with the _/_v_a_r_/_d_c_c_/_l_i_b_e_x_e_c_/_s_t_a_r_t_-_d_c_c_m or _v_a_r_/_d_c_c_/_l_i_b_e_x_e_c_/_r_c_D_C_C |
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44 script. |
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45 |
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46 The list of servers that ddccccmm contacts is in the memory mapped file _m_a_p |
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47 shared by local DCC clients. The file is maintained with cdcc(8). |
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48 |
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49 OOPPTTIIOONNSS |
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50 The following options are available: |
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51 |
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52 --VV displays the version of ddccccmm. |
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53 |
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54 --dd enables debugging output from the DCC client software. Additional |
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55 --dd options increase the number of messages. A single --dd |
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56 aborted SMTP transactions including those from some "dictionary |
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57 attacks." |
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58 |
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59 --bb causes the daemon to not detach itself from the controlling tty and |
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60 put itself into the background. |
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61 |
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62 --xx causes the daemon to try "extra hard" to contact a DCC server. |
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63 Since it is usually more important to deliver mail than to report |
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64 its checksums, ddccccmm normally does not delay too long while trying to |
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65 contact a DCC server. It will not try again for several seconds |
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66 after a failure. With --xx, it will always try to contact the DCC |
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67 server and it will tell the MTA to answer the DATA command with a |
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68 4yz temporary failure. |
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69 |
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70 --AA adds to existing X-DCC headers in the message instead of replacing |
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71 existing headers of the brand of the current server. |
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72 |
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73 --NN neither adds, deletes, nor replaces existing X-DCC headers in the |
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74 message. Each message is logged, rejected, and otherwise handled |
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75 the same. |
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76 |
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77 --QQ only queries the DCC server about the checksums of messages instead |
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78 of reporting and querying. This is useful when ddccccmm is used to fil- |
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79 ter mail that has already been reported to a DCC server by another |
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80 DCC client. No single mail message should be reported to a DCC |
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81 server more than once per recipient, because each report will |
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82 increase the apparent "bulkness" of the message. |
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83 |
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84 It is better to use _M_X_D_C_C lines in the global _w_h_i_t_e_c_l_n_t file for |
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85 your MX mail servers that use DCC than --QQ. |
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86 |
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87 --GG _o_n | _o_f_f | _n_o_I_P | _I_P_m_a_s_k_/_x_x |
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88 controls _g_r_e_y_l_i_s_t_i_n_g. At least one working greylist server must be |
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89 listed in the _m_a_p file in the DCC home directory. If more than one |
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90 is named, they must "flood" or change checksums and they must use |
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91 the same --GG parameters. See dccd(8). Usually all dccm or dccifd |
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92 DCC client processes use the same --GG parameters. |
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93 |
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94 _I_P_m_a_s_k_/_x_x and _n_o_I_P remove part or all of the IP address from the |
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95 greylist triple. The CIDR block size, _x_x, must be between 1 and |
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96 128. 96 is added to block sizes smaller than 33 to make them appro- |
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97 priate for the IPv6 addresses used by the DCC. _I_P_m_a_s_k_/_9_6 differs |
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98 from _n_o_I_P for IPv4 addresses, because the former retains the IPv4 to |
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99 IPv6 mapping prefix. |
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100 |
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101 --hh _h_o_m_e_d_i_r |
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102 overrides the default DCC home directory, _/_v_a_r_/_d_c_c. |
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103 |
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104 --II _u_s_e_r |
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105 specifies the UID and GID of the process. |
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106 |
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107 --pp _p_r_o_t_o_c_o_l_:_f_i_l_e_n_a_m_e | _p_r_o_t_o_c_o_l_:_p_o_r_t_@_h_o_s_t |
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108 specifies the protocol and address by which sendmail will contact |
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109 ddccccmm. The default is a UNIX domain socket in the "run" directory, |
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110 _/_v_a_r_/_r_u_n_/_d_c_c_/_d_c_c_m. (See also --RR)) This protocol and address must |
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111 match the value in _s_e_n_d_m_a_i_l_._c_f. This mechanism can be used to con- |
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112 nect ddccccmm on one computer to sendmail on another computer when a |
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113 port and host name or IP address are used. |
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114 |
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115 --mm _m_a_p |
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116 specifies a name or path of the memory mapped parameter file instead |
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117 of the default _m_a_p file in the DCC home directory. It should be |
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118 created with the cdcc(8) command. |
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119 |
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120 --ww _w_h_i_t_e_c_l_n_t |
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121 specifies an optional file containing filtering parameters as well |
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122 as SMTP client IP addresses, SMTP envelope values, and header values |
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123 of mail that is spam or is not spam and does not need a _X_-_D_C_C |
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124 header, and whose checksums should not be reported to the DCC |
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125 server. |
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126 |
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127 If the pathname _w_h_i_t_e_c_l_n_t is not absolute, it is relative to the DCC |
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128 home directory. |
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129 |
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130 The format of the ddccccmm whiteclnt file is the same as the _w_h_i_t_e_l_i_s_t |
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131 files used by dbclean(8) and the _w_h_i_t_e_c_l_n_t file used by dccproc(8). |
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132 See dcc(8) for a description of DCC white and blacklists. Because |
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133 the contents of the _w_h_i_t_e_c_l_n_t file are used frequently, a companion |
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134 file is automatically created and maintained. It has the same path- |
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135 name but with an added suffix of _._d_c_c_w and contains a memory mapped |
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136 hash table of the main file. |
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137 |
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138 A whitelist entry ("OK") or two or more semi-whitelistings ("OK2") |
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139 for one of the message's checksums prevents all of the message's |
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140 checksums from being reported to the DCC server and the addition of |
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141 a _X_-_D_C_C header line by ddccccmm A whitelist entry for a checksum also |
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142 prevents rejecting or discarding the message based on DCC recipient |
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143 counts as specified by --aa and --tt. Otherwise, one or more checksums |
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144 with blacklisting entries ("MANY") cause all of the message's check- |
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145 sums to be reported to the server with an addressee count of "MANY". |
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146 |
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147 If the message has a single recipient, an _e_n_v___T_o _w_h_i_t_e_c_l_n_t entry of |
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148 "OK" for the checksum of its recipient address acts like any other |
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149 _w_h_i_t_e_c_l_n_t entry of "OK." When the SMTP message has more than one |
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150 recipient, the effects can be complicated. When a message has sev- |
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151 eral recipients with some but not all listed in the _w_h_i_t_e_c_l_n_t file, |
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152 ddccccmm tries comply with the wishes of the users who want filtering as |
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153 well as those who don't by silently not delivering the message to |
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154 those who want filtering (i.e. are not whitelisted) and delivering |
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155 the message to don't want filtering. |
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156 |
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157 --UU _u_s_e_r_d_i_r_s |
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158 enables per-user _w_h_i_t_e_c_l_n_t files and log directories. Each target |
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159 of a message can have a directory of log files named |
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160 _u_s_e_d_i_r_s_/_$_{_d_c_c___u_s_e_r_d_i_r_}_/_l_o_g where _$_{_d_c_c___u_s_e_r_d_i_r_} is the _s_e_n_d_m_a_i_l_._c_f |
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161 macro described below. If _$_{_d_c_c___u_s_e_r_d_i_r_} is not set, |
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162 _u_s_e_r_d_i_r_s_/_$_{_r_c_p_t___m_a_i_l_e_r_}_/_$_{_r_c_p_t___a_d_d_r_}_/_l_o_g is used. The most likely |
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163 value of _m_a_i_l_e_r is _l_o_c_a_l. Appropriate values for both |
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164 _$_{_r_c_p_t___m_a_i_l_e_r_} and _$_{_r_c_p_t___a_d_d_r_} can be seen by examining _e_n_v___T_o |
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165 lines in --ll _l_o_g_d_i_r files. If it is not absolute, _u_s_e_r_d_i_r_s is rela- |
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166 tive to the DCC home directory. The directory containing the log |
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167 files must be named _l_o_g and it must be writable by the ddccccmm process. |
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168 Each log directory must exist or logging for the corresponding is |
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169 silently disabled. The files created in the log directory are owned |
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170 by the UID of the ddccccmm process, but they have _g_r_o_u_p and _o_t_h_e_r read |
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171 and write permissions copied from the corresponding _l_o_g directory. |
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172 To ensure the privacy of mail, it may be good to make the directo- |
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173 ries readable only by _o_w_n_e_r and _g_r_o_u_p, and to use a cron script that |
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174 changes the owner of each file to match the grandparent _a_d_d_r direc- |
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175 tory. |
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176 |
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177 There can also be a per -user whitelist file named |
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178 _u_s_e_r_d_i_r_s_/_$_{_d_c_c___u_s_e_r_d_i_r_}_/_w_h_i_t_e_c_l_n_t or if _$_{_d_c_c___u_s_e_r_d_i_r_} is not set, |
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179 _u_s_e_r_d_i_r_s_/_$_{_r_c_p_t___m_a_i_l_e_r_}_/_$_{_r_c_p_t___a_d_d_r_} per-user whitelist files. Any |
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180 checksum that is not white- or blacklisted by an individual |
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181 addressee's _w_h_i_t_e_c_l_n_t file is checked in the main --ww --wwhhiitteeccllnntt |
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182 file. A missing per-addressee _w_h_i_t_e_c_l_n_t file is the same as an |
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183 empty file. Relative paths for files included in per-addressee |
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184 files are resolved in the DCC home directory. The _w_h_i_t_e_c_l_n_t files |
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185 and the _a_d_d_r directories containing them must be writable by the |
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186 ddccccmm process. |
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187 |
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188 _O_p_t_i_o_n lines in per-user whiteclnt files can be used to modify many |
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189 aspects of ddccccmm filtering, as described in the main dcc man page. |
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190 For example, an _o_p_t_i_o_n _d_c_c_-_o_f_f line turns off DCC filtering for |
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191 individual mailboxes. |
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192 |
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193 --aa _I_G_N_O_R_E | _R_E_J_E_C_T | _D_I_S_C_A_R_D |
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194 specifies the action taken when DCC server counts or --tt thresholds |
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195 say that a message is unsolicited and bulk. _I_G_N_O_R_E causes the mes- |
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196 sage to be unaffected except for adding the _X_-_D_C_C header line to the |
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197 message. This turns off DCC filtering. |
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198 |
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199 Spam can also be _R_E_J_E_C_Ted or accepted and silently _D_I_S_C_A_R_Ded without |
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200 being delivered to local mailboxes. The default is _R_E_J_E_C_T. |
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201 |
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202 Mail forwarded via IP addresses marked _M_X or _M_X_D_C_C in the main |
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203 _w_h_i_t_e_c_l_n_t file is treated as if --aa _D_I_S_C_A_R_D were specified. This |
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204 prevents "bouncing" spam. |
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205 |
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206 Determinations that mail is or is not spam from sendmail via |
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207 _$_{_d_c_c___i_s_s_p_a_m_} or _$_{_d_c_c___n_o_t_s_p_a_m_} macros override --aa. The effects of |
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208 the --ww _w_h_i_t_e_c_l_n_t are not affected by --aa. |
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209 |
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210 --tt _t_y_p_e_,[_l_o_g_-_t_h_o_l_d_,]_r_e_j_-_t_h_o_l_d |
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211 sets logging and "spam" thresholds for checksum _t_y_p_e. The checksum |
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212 types are _I_P, _e_n_v___F_r_o_m, _F_r_o_m, _M_e_s_s_a_g_e_-_I_D, _s_u_b_s_t_i_t_u_t_e, _R_e_c_e_i_v_e_d, |
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213 _B_o_d_y, _F_u_z_1, _F_u_z_2, _r_e_p_-_t_o_t_a_l, and _r_e_p. The first six, _I_P through |
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214 _s_u_b_s_t_i_t_u_t_e, have no effect except when a local DCC server configured |
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215 with --KK is used. The _s_u_b_s_t_i_t_u_t_e thresholds apply to the first sub- |
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216 stitute heading encountered in the mail message. The string _A_L_L |
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217 sets thresholds for all types, but is unlikely to be useful except |
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218 for setting logging thresholds. The string _C_M_N specifies the com- |
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219 monly used checksums _B_o_d_y, _F_u_z_1, and _F_u_z_2. _R_e_j_-_t_h_o_l_d and _l_o_g_-_t_h_o_l_d |
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220 must be numbers, the string _N_E_V_E_R, or the string _M_A_N_Y indicating |
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221 millions of targets. Counts from the DCC server as large as the |
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222 threshold for any single type are taken as sufficient evidence that |
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223 the message should be logged or rejected. |
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224 |
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225 _L_o_g_-_t_h_o_l_d is the threshold at which messages are logged. It can be |
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226 handy to log messages at a lower threshold to find solicited bulk |
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227 mail sources such as mailing lists. If no logging threshold is set, |
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228 only rejected mail and messages with complicated combinations of |
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229 white and blacklisting are logged. Messages that reach at least one |
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230 of their rejection thresholds are logged regardless of logging |
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231 thresholds. |
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232 |
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233 _R_e_j_-_t_h_o_l_d is the threshold at which messages are considered "bulk," |
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234 and so should be rejected or discarded if not whitelisted. |
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235 |
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236 DCC Reputation thresholds in the commercial version of the DCC are |
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237 controlled by thresholds on checksum types _r_e_p and _r_e_p_-_t_o_t_a_l. Mes- |
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238 sages from an IP address that the DCC database says has sent more |
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239 than --tt _r_e_p_-_t_o_t_a_l_,_l_o_g_-_t_h_o_l_d messages are logged. A DCC Reputation |
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240 is computed for messages received from IP addresses that have sent |
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241 more than --tt _r_e_p_-_t_o_t_a_l_,_l_o_g_-_t_h_o_l_d messages. The DCC Reputation of an |
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242 IP address is the percentage of its messages that have been detected |
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243 as bulk or having at least 10 recipients. The defaults are equiva- |
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244 lent to --tt _r_e_p_,_n_e_v_e_r and --tt _r_e_p_-_t_o_t_a_l_,_n_e_v_e_r_,_2_0. |
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245 |
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246 Bad DCC Reputations do not reject mail unless enabled by an _o_p_t_i_o_n |
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247 _D_C_C_-_r_e_p_-_o_n line in a _w_h_i_t_e_c_l_n_t file. |
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248 |
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249 The checksums of locally whitelisted messages are not checked with |
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250 the DCC server and so only the number of targets of the current copy |
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251 of a whitelisted message are compared against the thresholds. |
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252 |
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253 The default is _A_L_L_,_N_E_V_E_R, so that nothing is discarded, rejected, or |
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254 logged. A common choice is _C_M_N_,_2_5_,_5_0 to reject or discard mail with |
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255 common bodies except as overridden by the whitelist of the DCC |
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256 server, the sendmail _$_{_d_c_c___i_s_s_p_a_m_} and _$_{_d_c_c___n_o_t_s_p_a_m_} macros, and |
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257 --gg, and --ww. |
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258 |
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259 --gg [_n_o_t_-]_t_y_p_e |
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260 indicates that whitelisted, _O_K or _O_K_2, counts from the DCC server |
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261 for a type of checksum are to be believed. They should be ignored |
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262 if prefixed with _n_o_t_-. _T_y_p_e is one of the same set of strings as |
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263 for --tt. Only _I_P, _e_n_v___F_r_o_m, and _F_r_o_m are likely choices. By default |
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264 all three are honored, and hence the need for _n_o_t_-. |
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265 |
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266 --SS _h_d_r |
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267 adds to the list of substitute or locally chosen headers that are |
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268 checked with the --ww _w_h_i_t_e_c_l_n_t file and sent to the DCC server. The |
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269 checksum of the last header of type _h_d_r found in the message is |
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270 checked. _H_d_r can be _H_E_L_O to specify the SMTP envelope HELO value. |
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271 _H_d_r can also be _m_a_i_l___h_o_s_t to specify the sendmail "resolved" host |
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272 name from the Mail_from value in the SMTP envelope. As many as six |
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273 different substitute headers can be specified, but only the checksum |
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274 of the first of the six will be sent to the DCC server. |
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275 |
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276 --ll _l_o_g_d_i_r |
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277 specifies a directory in which files containing copies of messages |
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278 processed by ddccccmm are kept. They can be copied to per-user directo- |
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279 ries specified with --UU. Information about other recipients of a |
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|
280 message is deleted from the per-user copies. |
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|
281 |
|
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282 See the FILES section below concerning the contents of the files. |
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283 See also the _o_p_t_i_o_n _l_o_g_-_s_u_b_d_i_r_e_c_t_o_r_y_-_{_d_a_y_,_h_o_u_r_,_m_i_n_u_t_e_} lines in |
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284 _w_h_i_t_e_c_l_n_t files described in dcc(8). |
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285 |
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286 The directory is relative to the DCC home directory if it is not |
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287 absolute |
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288 |
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289 --RR _r_u_n_d_i_r |
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290 specifies the "run" directory where the UNIX domain socket and file |
|
|
291 containing the daemon's process ID are stored. The default value is |
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292 /var/run/dcc . |
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293 |
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294 --rr _r_e_j_e_c_t_i_o_n_-_m_s_g |
|
|
295 specifies the rejection message in --oo proxy mode for unsolicited |
|
|
296 bulk mail or for mail temporarily blocked by _g_r_e_y_l_i_s_t_i_n_g when --GG is |
|
|
297 specified. The first --rr _r_e_j_e_c_t_i_o_n_-_m_s_g replaces the default bulk |
|
|
298 mail rejection message, "5.7.1 550 mail %ID from %CIP rejected by |
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299 DCC". The second replaces "4.2.1 452 mail %ID from %CIP temporary |
|
|
300 greylist embargoed". The third --rr _r_e_j_e_c_t_i_o_n_-_m_s_g replaces the |
|
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301 default SMTP rejection message "5.7.1 550 %ID bad reputation; see |
|
|
302 http://commercial-dcc.rhyolite.com/cgi-bin/reps.cgi?tgt=%CIP" for |
|
|
303 mail with bad DCC Reputations. If _r_e_j_e_c_t_i_o_n_-_m_s_g is the zero-length |
|
|
304 string, the --rr setting is counted but the corresponding message is |
|
|
305 not changed. |
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306 |
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|
307 _R_e_j_e_c_t_i_o_n_-_m_s_g can contain specific information about the mail mes- |
|
|
308 sage. The following strings starting with % are replaced with the |
|
|
309 corresponding values: |
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|
310 %ID message ID such as the unique part of log file name or |
|
|
311 sendmail queue ID |
|
|
312 %CIP SMTP client IP address |
|
|
313 %BTYPE type of DNS blacklist hit, such as "SMTP client", |
|
|
314 "mail_host", or "URL NS" |
|
|
315 %BTGT IP address or name declared bad by DNS blacklist |
|
|
316 %BPROBE domain name found in DNS blacklist such as |
|
|
317 4.3.2.10.example.com |
|
|
318 %BRESULT value of the %BPROBE domain name found in DNS black- |
|
|
319 list |
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320 |
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|
321 A common alternate for the bulk mail rejection message is "4.7.1 451 |
|
|
322 Access denied by DCC" to tell the sending mail system to continue |
|
|
323 trying. Use a 4yz response with caution, because it is likely to |
|
|
324 delay for days a delivery failure message for false positives. If |
|
|
325 the rejection message does not start with an RFC 1893 status code |
|
|
326 and RFC 2821 reply code, 5.7.1 and 550 or 4.2.1 and 452 are used. |
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327 |
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|
328 See also --BB _s_e_t_:_r_e_j_-_m_s_g_=_r_e_j_e_c_t_i_o_n_-_m_s_g to set the status message for |
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|
329 mail rejected by DNS blacklists. |
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330 |
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331 --jj _m_a_x_j_o_b_s |
|
|
332 limits the number of simultaneous requests that will be processed. |
|
|
333 The default value is the maximum number that seems to be possible |
|
|
334 given system limits on open files, select() bit masks, and so forth. |
|
|
335 Start ddccccmm with --dd and see the starting message in the system log to |
|
|
336 see the limit. |
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|
337 |
|
|
338 --BB _d_n_s_b_l_-_o_p_t_i_o_n |
|
|
339 enables DNS blacklist checks of the SMTP client IP address, SMTP |
|
|
340 envelope Mail_From sender domain name, and of host names in URLs in |
|
|
341 the message body. Body URL blacklisting has too many false posi- |
|
|
342 tives to use on abuse mailboxes. It is less effective than |
|
|
343 greylisting with dccm(8) or dccifd(8) but can be useful in situa- |
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|
344 tions where greylisting cannot be used. |
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345 |
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|
346 _D_n_s_b_l_-_o_p_t_i_o_n is either one of the --BB _s_e_t_:_o_p_t_i_o_n forms or |
|
|
347 --BB _d_o_m_a_i_n[_,_I_P_a_d_d_r[_/_x_x[_,_b_l_t_y_p_e]]] |
|
|
348 _D_o_m_a_i_n is a DNS blacklist domain such as example.com that will be |
|
|
349 searched. _I_P_a_d_d_r[_/_x_x_x] is the string "any" an IP address in the DNS |
|
|
350 blacklist that indicates that the mail message should be rejected, |
|
|
351 or a CIDR block covering results from the DNS blacklist. |
|
|
352 "127.0.0.2" is assumed if _I_P_a_d_d_r is absent. IPv6 addresses can be |
|
|
353 specified with the usual colon (:) notation. Names can be used |
|
|
354 instead of numeric addresses. The type of DNS blacklist is speci- |
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|
355 fied by _b_l_t_y_p_e as _n_a_m_e, _I_P_v_4, or _I_P_v_6. Given an envelope sender |
|
|
356 domain name or a domain name in a URL of spam.domain.org and a |
|
|
357 blacklist of type _n_a_m_e, spam.domain.org.example.com will be tried. |
|
|
358 Blacklist types of _I_P_v_4 and _I_P_v_6 require that the domain name in a |
|
|
359 URL sender address be resolved into an IPv4 or IPv6 address. The |
|
|
360 address is then written as a reversed string of decimal octets to |
|
|
361 check the DNS blacklist, as in 2.0.0.127.example.com, |
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|
362 |
|
|
363 More than one blacklist can be specified and blacklists can be |
|
|
364 grouped. All searching within a group is stopped at the first posi- |
|
|
365 tive result. |
|
|
366 |
|
|
367 Positive results are ignored after being logged unless an |
|
|
368 _o_p_t_i_o_n _D_N_S_B_L_-_o_n line appears in the global or per-user _w_h_i_t_e_c_l_n_t |
|
|
369 file. |
|
|
370 |
|
|
371 --BB _s_e_t_:_n_o_-_c_l_i_e_n_t |
|
|
372 says that SMTP client IP addresses and reverse DNS domain names |
|
|
373 should not be checked in the following blacklists. |
|
|
374 --BB _s_e_t_:_c_l_i_e_n_t restores the default for the following black- |
|
|
375 lists. |
|
|
376 |
|
|
377 --BB _s_e_t_:_n_o_-_m_a_i_l___h_o_s_t |
|
|
378 says that SMTP envelope Mail_From sender domain names should |
|
|
379 not be checked in the following blacklists. --BB _s_e_t_:_m_a_i_l___h_o_s_t |
|
|
380 restores the default. |
|
|
381 |
|
|
382 --BB _s_e_t_:_n_o_-_U_R_L |
|
|
383 says that URLs in the message body should not be checked in the |
|
|
384 in the following blacklists. --BB _s_e_t_:_U_R_L restores the default. |
|
|
385 |
|
|
386 --BB _s_e_t_:_n_o_-_M_X |
|
|
387 says MX servers of sender Mail_From domain names and host names |
|
|
388 in URLs should not be checked in the following blacklists. |
|
|
389 --BB _s_e_t_:_M_X restores the default. |
|
|
390 |
|
|
391 --BB _s_e_t_:_n_o_-_N_S |
|
|
392 says DNS servers of sender Mail_From domain names and host |
|
|
393 names in URLs should not be checked in the following black- |
|
|
394 lists. --BB _s_e_t_:_N_S restores the default. |
|
|
395 |
|
|
396 --BB _s_e_t_:_d_e_f_a_u_l_t_s |
|
|
397 is equivalent to all of --BB _s_e_t_:_n_o_-_t_e_m_p_-_f_a_i_l --BB _s_e_t_:_c_l_i_e_n_t |
|
|
398 --BB _s_e_t_:_m_a_i_l___h_o_s_t --BB _s_e_t_:_U_R_L --BB _s_e_t_:_M_X and --BB _s_e_t_:_N_S |
|
|
399 |
|
|
400 --BB _s_e_t_:_g_r_o_u_p_=_X |
|
|
401 adds later DNS blacklists specified with |
|
|
402 --BB _d_o_m_a_i_n[_,_I_P_a_d_d_r[_/_x_x[_,_b_l_t_y_p_e]]] |
|
|
403 to group 1, 2, or 3. |
|
|
404 |
|
|
405 --BB _s_e_t_:_d_e_b_u_g_=_X |
|
|
406 sets the DNS blacklist logging level |
|
|
407 |
|
|
408 --BB _s_e_t_:_m_s_g_-_s_e_c_s_=_S |
|
|
409 limits ddccccmm to _S seconds total for checking all DNS blacklists. |
|
|
410 The default is 25. |
|
|
411 |
|
|
412 --BB _s_e_t_:_U_R_L_-_s_e_c_s_=_S |
|
|
413 limits ddccccmm to at most _S seconds resolving and checking any |
|
|
414 single URL. The default is 11. Some spam contains dozens of |
|
|
415 URLs and that some "spamvertised" URLs contain host names that |
|
|
416 need minutes to resolve. Busy mail systems cannot afford to |
|
|
417 spend minutes checking each incoming mail message. |
|
|
418 |
|
|
419 --BB _s_e_t_:_r_e_j_-_m_s_g_=_r_e_j_e_c_t_i_o_n_-_m_s_g |
|
|
420 sets the SMTP rejection message for the following blacklists. |
|
|
421 _R_e_j_e_c_t_i_o_n_-_m_s_g must be in the same format as for --rr. If |
|
|
422 _r_e_j_e_c_t_i_o_n_-_m_s_g is null, the default is restored. The default |
|
|
423 DNS blacklist rejection message is the first message set with |
|
|
424 --rr. |
|
|
425 |
|
|
426 --BB _s_e_t_:_t_e_m_p_-_f_a_i_l |
|
|
427 causes ddccccmm to the MTA to answer the SMTP DATA command with |
|
|
428 452 4.2.1 mail %ID from %CIP temporary delayed for DNSBL |
|
|
429 if any DNS answer required for a DNSBL in the current group |
|
|
430 times out, including resolving names in URLs. |
|
|
431 |
|
|
432 --BB _s_e_t_:_n_o_-_t_e_m_p_-_f_a_i_l |
|
|
433 restores the default of assuming a negative answer for DNS |
|
|
434 responses that take too long. |
|
|
435 |
|
|
436 --BB _s_e_t_:_m_a_x_j_o_b_s_=_X |
|
|
437 sets maximum number of helper processes to _X. In order to use |
|
|
438 typical single-threaded DNS resolver libraries, ddccccmm uses |
|
|
439 fleets of helper processes. It is rarely a good idea to change |
|
|
440 the default, which is the same as the maximum number of simul- |
|
|
441 taneous jobs set with --jj. |
|
|
442 |
|
|
443 --BB _s_e_t_:_p_r_o_g_p_a_t_h_=_/_v_a_r_/_d_c_c_/_l_i_b_e_x_e_c_/_d_n_s_-_h_e_l_p_e_r |
|
|
444 changes the path to the helper program. |
|
|
445 |
|
|
446 --LL _l_t_y_p_e_,_f_a_c_i_l_i_t_y_._l_e_v_e_l |
|
|
447 specifies how messages should be logged. _L_t_y_p_e must be _e_r_r_o_r, _i_n_f_o, |
|
|
448 or _o_f_f to indicate which of the two types of messages are being con- |
|
|
449 trolled or to turn off all syslog(3) messages from ddccccmm. _L_e_v_e_l must |
|
|
450 be a syslog(3) level among _E_M_E_R_G, _A_L_E_R_T, _C_R_I_T, _E_R_R, _W_A_R_N_I_N_G, _N_O_T_I_C_E, |
|
|
451 _I_N_F_O, and _D_E_B_U_G. _F_a_c_i_l_i_t_y must be among _A_U_T_H, _A_U_T_H_P_R_I_V, _C_R_O_N, |
|
|
452 _D_A_E_M_O_N, _F_T_P, _K_E_R_N, _L_P_R, _M_A_I_L, _N_E_W_S, _U_S_E_R, _U_U_C_P, and _L_O_C_A_L_0 through |
|
|
453 _L_O_C_A_L_7. The default is equivalent to |
|
|
454 --LL _i_n_f_o_,_M_A_I_L_._N_O_T_I_C_E --LL _e_r_r_o_r_,_M_A_I_L_._E_R_R |
|
|
455 |
|
|
456 ddccccmm normally sends counts of mail rejected and so forth the to system |
|
|
457 log at midnight. The SIGUSR1 signal sends an immediate report to the |
|
|
458 system log. They will be repeated every 24 hours instead of at midnight. |
|
|
459 |
|
|
460 SSEENNDDMMAAIILL MMAACCRROOSS |
|
|
461 Sendmail can affect ddccccmm with the values of some _s_e_n_d_m_a_i_l_._c_f macros. |
|
|
462 These macro names must be added to the Milter.macros option statements in |
|
|
463 _s_e_n_d_m_a_i_l_._c_f as in the example "Feature" file dcc.m4. |
|
|
464 |
|
|
465 _$_{_d_c_c___i_s_s_p_a_m_} causes a mail message to be reported to the DCC server as |
|
|
466 having been addressed to "MANY" recipients. The |
|
|
467 _$_{_d_c_c___i_s_s_p_a_m_} macro is ignored if the _$_{_d_c_c___n_o_t_s_p_a_m_} macro |
|
|
468 is set to a non-null string |
|
|
469 |
|
|
470 If the value of the _$_{_d_c_c___i_s_s_p_a_m_} is null, ddccccmm uses SMTP |
|
|
471 rejection messages controlled by --aa and --rr. If the value |
|
|
472 of the _$_{_d_c_c___i_s_s_p_a_m_} macro starts with "DISCARD", the mail |
|
|
473 message is silently discarded as with --aa _D_I_S_C_A_R_D_. If value |
|
|
474 of the macro not null and does not start with "DISCARD", |
|
|
475 it is used as the SMTP error message given to the SMTP |
|
|
476 client trying to send the rejected message. The message |
|
|
477 starts with an optional SMTP error type and number fol- |
|
|
478 lowed by text. |
|
|
479 |
|
|
480 The --aa option does not effect messages marked spam with |
|
|
481 _$_{_d_c_c___i_s_s_p_a_m_}. When the _$_{_d_c_c___i_s_s_p_a_m_} macro is set, the |
|
|
482 message is rejected or discarded despite local or DCC |
|
|
483 database whitelist entries. The local whitelist does con- |
|
|
484 trol whether the message's checksums will be reported to |
|
|
485 the DCC server and an _X_-_D_C_C SMTP header line will be |
|
|
486 added. |
|
|
487 |
|
|
488 _$_{_d_c_c___n_o_t_s_p_a_m_} |
|
|
489 causes a message not be considered unsolicited bulk |
|
|
490 despite evidence to the contrary. It also prevents ddccccmm |
|
|
491 from reporting the checksums of the message to the DCC |
|
|
492 server and from adding an _X_-_D_C_C header line. |
|
|
493 |
|
|
494 When the macro is set by the _s_e_n_d_m_a_i_l_._c_f rules, |
|
|
495 _$_{_d_c_c___n_o_t_s_p_a_m_} macros overrides DCC threshlds that say the |
|
|
496 message should be rejected as well as the effects of the |
|
|
497 _$_{_d_c_c___i_s_s_p_a_m_} macro. |
|
|
498 |
|
|
499 _$_{_d_c_c___m_a_i_l___h_o_s_t_} |
|
|
500 specifies the name of the SMTP client that is sending the |
|
|
501 message. This macro is usually the same as the _m_a_i_l___h_o_s_t |
|
|
502 macro. They can differ when a sendmail "smart relay" is |
|
|
503 involved. The _$_{_d_c_c___m_a_i_l___h_o_s_t_} macro does not work if |
|
|
504 _F_E_A_T_U_R_E_(_d_e_l_a_y___c_h_e_c_k_s_) is used. |
|
|
505 |
|
|
506 _$_{_d_c_c___u_s_e_r_d_i_r_} |
|
|
507 is the per-user whitelist and log directory for a recipi- |
|
|
508 ent. If the macro is not set in sendmail.cf, |
|
|
509 $&{rcpt_mailer}/$&{rcpt_addr} is assumed, but with the |
|
|
510 recipient address converted to lower case. Whatever value |
|
|
511 is used, the directory name after the last slash (/) char- |
|
|
512 acter is converted to lower case. Any value containing |
|
|
513 the string "/../" is ignored. |
|
|
514 |
|
|
515 This macro also does not work if _F_E_A_T_U_R_E_(_d_e_l_a_y___c_h_e_c_k_s_) is |
|
|
516 used. |
|
|
517 |
|
|
518 The following two lines in a sendmail mc file have the |
|
|
519 same effect as not defining the ${dcc_userdir} macro, pro- |
|
|
520 vided _F_E_A_T_U_R_E_(_d_c_c_) is also used and the sendmail |
|
|
521 _c_f_/_f_e_a_t_u_r_e directory has a symbolic link to the |
|
|
522 _m_i_s_c_/_d_c_c_._m_4 file. |
|
|
523 |
|
|
524 SLocal_check_rcpt |
|
|
525 R$* $: $1 $(macro {dcc_userdir} $@ $&{rcpt_mailer}/$&{rcpt_addr} $)) |
|
|
526 |
|
|
527 FFIILLEESS |
|
|
528 /var/dcc is the DCC home directory in which other files are found. |
|
|
529 /var/dcc/libexec/start-dccm |
|
|
530 is a script used to ddccccmm. |
|
|
531 dcc/dcc_conf |
|
|
532 contains parameters used by the scripts to start DCC daemons |
|
|
533 and cron jobs. |
|
|
534 logdir is an optional directory specified with --ll and containing |
|
|
535 marked mail. Each file in the directory contains one message, |
|
|
536 at least one of whose checksums reached its --tt thresholds or |
|
|
537 that is interesting for some other reason. Each file starts |
|
|
538 with lines containing the date when the message was received, |
|
|
539 the IP address of the SMTP client, and SMTP envelope values. |
|
|
540 Those lines are followed by the body of the SMTP message |
|
|
541 including its header as it was received by sendmail and with- |
|
|
542 out any new or changed header lines. Only approximately the |
|
|
543 first 32 KBytes of the body are recorded unless modified by |
|
|
544 _._/_c_o_n_f_i_g_u_r_e _-_-_w_i_t_h_-_m_a_x_-_l_o_g_-_s_i_z_e_=_x_x The checksums for the mes- |
|
|
545 sage follow the body. They are followed by lines indicating |
|
|
546 that the _$_{_d_c_c___i_s_s_p_a_m_} or _$_{_d_c_c___n_o_t_s_p_a_m_} _s_e_n_d_m_a_i_l_._c_f macros |
|
|
547 were set or one of the checksums is white- or blacklisted by |
|
|
548 the --ww _w_h_i_t_e_c_l_n_t file. Each file ends with the _X_-_D_C_C header |
|
|
549 line added to the message and the disposition of the message |
|
|
550 including SMTP status message if appropriate. |
|
|
551 map is the memory mapped file of information concerning DCC |
|
|
552 servers in the DCC home directory. |
|
|
553 whiteclnt contains the client whitelist in the format described in |
|
|
554 dcc(8). |
|
|
555 whiteclnt.dccw |
|
|
556 is a memory mapped hash table of the _w_h_i_t_e_c_l_n_t file. |
|
|
557 dccm.pid in the --RR _r_u_n_d_i_r directory contains daemon's process ID. The |
|
|
558 string ``dccm'' is replaced by the file name containing the |
|
|
559 daemon to facilitate running multiple daemons, probably con- |
|
|
560 nected to remote instances of sendmail using TCP/IP instead of |
|
|
561 a UNIX domain socket. See also --RR. |
|
|
562 /var/run/dcc/dccm |
|
|
563 is the default UNIX domain socket used by the sendmail milter |
|
|
564 interface. See also --RR. |
|
|
565 sendmail.cf |
|
|
566 is the sendmail(8) control file. |
|
|
567 misc/dcc.m4 |
|
|
568 sendmail mc file that should have a symbolic link in the send- |
|
|
569 mail cf/feature directory so that _F_E_A_T_U_R_E_(_d_c_c_) can be used in |
|
|
570 a sendmail mc file. |
|
|
571 |
|
|
572 EEXXAAMMPPLLEESS |
|
|
573 DDccccmm should be started before sendmail with something like the script |
|
|
574 _/_v_a_r_/_d_c_c_/_l_i_b_e_x_e_c_/_s_t_a_r_t_-_d_c_c_m_. It looks for common DCC parameters in the |
|
|
575 _d_c_c___c_o_n_f file in the DCC home directory, _/_v_a_r_/_d_c_c_. |
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|
576 |
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577 Those numbers should modified to fit local conditions. It might be wise |
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578 to replace the "100" numbers with much larger values or with "MANY" until |
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579 a few weeks of monitoring the log directory show that sources of mailing |
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580 lists are in the server's whitelist file (see dccd(8)) or the local |
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581 _w_h_i_t_e_c_l_n_t file. |
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582 |
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583 It is usually necessary to regularly delete old log files with a script |
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584 like /var/dcc/libexec/cron-dccd. |
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585 |
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586 On systems unlike modern FreeBSD and other UNIX-like systems which |
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587 include sendmail milter support, sendmail must be built with the milter |
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588 interface, such as by creating a _d_e_v_t_o_o_l_s_/_S_i_t_e_/_s_i_t_e_._c_o_n_f_i_g_._m_4 or similar |
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589 file containing something like the following lines: |
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590 |
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591 APPENDDEF(`conf_sendmail_ENVDEF', `-D_FFR_MILTER=1') |
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592 APPENDDEF(`conf_libmilter_ENVDEF', `-D_FFR_MILTER=1') |
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593 |
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594 Appropriate lines invoking the milter interface must be added to |
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595 _s_e_n_d_m_a_i_l_._c_f_. That can be done by putting a symbolic link to the the |
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596 misc/dcc.m4 file in the DCC source to the sendmail cf/feature directory |
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597 and adding the line |
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598 |
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599 FEATURE(dcc) |
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600 |
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601 to the local .mc file. |
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602 |
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603 Note that ddccccmm should not be used with the Postfix milter mechanism. |
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604 Instead use dccifd(8) as a before-queue filter as described in that man |
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605 page. |
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606 |
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607 SSEEEE AALLSSOO |
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608 cdcc(8), dbclean(8), dcc(8), dccd(8), dblist(8), dccifd(8), dccproc(8), |
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609 dccsight(8), sendmail(8). |
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610 |
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611 HHIISSTTOORRYY |
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612 Distributed Checksum Clearinghouses are based on an idea of Paul Vixie. |
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|
613 Implementation of ddccccmm was started at Rhyolite Software in 2000. This |
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614 document describes version 1.3.103. |
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615 |
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616 BBUUGGSS |
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617 ddccccmm uses --tt where dccproc(8) uses --cc. |
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618 |
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619 Systems without setrlimit(2) and getrlimit(2) RLIMIT_NOFILE can have |
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620 problems with the default limit on the number of simultaneous jobs, the |
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621 value of --jj. Every job requires four open files. These problems are |
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622 usually seen with errors messages that say something like |
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623 dccm[24448]: DCC: accept() returned invalid socket |
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624 A fix is to use a smaller value for --jj or to allow ddccccmm to open more |
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625 files. Sendmail version 8.13 and later can be told to poll() instead of |
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|
626 select with SM_CONF_POLL. Some older versions of sendmail knew about |
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|
627 FFR_USE_POLL. One of the following lines in your devtools/Site/site.con- |
|
|
628 fig.m4 file can help: |
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|
629 |
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|
630 APPENDDEF(`conf_libmilter_ENVDEF', `-DSM_CONF_POLL') |
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|
631 APPENDDEF(`conf_libmilter_ENVDEF', `-DFFR_USE_POLL') |
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632 |
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633 On many systems with sendmail 8.11.3 and preceding, a bug in the sendmail |
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634 milter mechanism causes ddccccmm to die with a core file when given a signal. |
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635 |
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636 February 26, 2009 |
