Mercurial > notdcc
diff dccm.0 @ 0:c7f6b056b673
First import of vendor version
| author | Peter Gervai <grin@grin.hu> |
|---|---|
| date | Tue, 10 Mar 2009 13:49:58 +0100 |
| parents | |
| children |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/dccm.0 Tue Mar 10 13:49:58 2009 +0100 @@ -0,0 +1,636 @@ +dccm(8) Distributed Checksum Clearinghouse dccm(8) + +NNAAMMEE + ddccccmm -- Distributed Checksum Clearinghouse Milter Interface + +SSYYNNOOPPSSIISS + 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] + [--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] + [--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] + [--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] + [--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] + [--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] + +DDEESSCCRRIIPPTTIIOONN + ddccccmm is a daemon built with the sendmail milter interface intended to + connect sendmail(8) to DCC servers. When built with the milter filter + machinery and configured to talk to ddccccmm in the _s_e_n_d_m_a_i_l_._c_f file, send- + mail passes all email to ddccccmm which in turn reports related checksums to + the nearest DCC server. ddccccmm then adds an _X_-_D_C_C SMTP header line to the + message. Sendmail is told to reject the message if it is unsolicited + bulk mail. + + DDccccmm sends reports of checksums related to mail received by DCC clients + and queries about the total number of reports of particular checksums. A + DCC server receives _n_o mail, address, headers, or other information, but + only cryptographically secure checksums of such information. A DCC + server cannot determine the text or other information that corresponds to + the checksums it receives. Its only acts as a clearinghouse of counts + for checksums computed by clients. For complete privacy as far as the + DCC is concerned, the checksums of purely internal mail or other mail + that is known to not be unsolicited bulk can be listed in a whitelist to + not be reported to the DCC server. + + Since the checksums of messages that are whitelisted locally by the --ww + _w_h_i_t_e_c_l_n_t file are not reported to the DCC server, ddccccmm knows nothing + about the total recipient counts for their checksums and so cannot add + _X_-_D_C_C header lines to such messages. Sendmail does not tell ddccccmm about + messages that are not received by sendmail via SMTP, including messages + submitted locally and received via UUCP, and so they also do not receive + _X_-_D_C_C header lines. + + Enable the daemon and put its parameters in the _d_c_c___c_o_n_f file and start + 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 + script. + + The list of servers that ddccccmm contacts is in the memory mapped file _m_a_p + shared by local DCC clients. The file is maintained with cdcc(8). + + OOPPTTIIOONNSS + The following options are available: + + --VV displays the version of ddccccmm. + + --dd enables debugging output from the DCC client software. Additional + --dd options increase the number of messages. A single --dd + aborted SMTP transactions including those from some "dictionary + attacks." + + --bb causes the daemon to not detach itself from the controlling tty and + put itself into the background. + + --xx causes the daemon to try "extra hard" to contact a DCC server. + Since it is usually more important to deliver mail than to report + its checksums, ddccccmm normally does not delay too long while trying to + contact a DCC server. It will not try again for several seconds + after a failure. With --xx, it will always try to contact the DCC + server and it will tell the MTA to answer the DATA command with a + 4yz temporary failure. + + --AA adds to existing X-DCC headers in the message instead of replacing + existing headers of the brand of the current server. + + --NN neither adds, deletes, nor replaces existing X-DCC headers in the + message. Each message is logged, rejected, and otherwise handled + the same. + + --QQ only queries the DCC server about the checksums of messages instead + of reporting and querying. This is useful when ddccccmm is used to fil- + ter mail that has already been reported to a DCC server by another + DCC client. No single mail message should be reported to a DCC + server more than once per recipient, because each report will + increase the apparent "bulkness" of the message. + + 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 + your MX mail servers that use DCC than --QQ. + + --GG _o_n | _o_f_f | _n_o_I_P | _I_P_m_a_s_k_/_x_x + controls _g_r_e_y_l_i_s_t_i_n_g. At least one working greylist server must be + listed in the _m_a_p file in the DCC home directory. If more than one + is named, they must "flood" or change checksums and they must use + the same --GG parameters. See dccd(8). Usually all dccm or dccifd + DCC client processes use the same --GG parameters. + + _I_P_m_a_s_k_/_x_x and _n_o_I_P remove part or all of the IP address from the + greylist triple. The CIDR block size, _x_x, must be between 1 and + 128. 96 is added to block sizes smaller than 33 to make them appro- + priate for the IPv6 addresses used by the DCC. _I_P_m_a_s_k_/_9_6 differs + from _n_o_I_P for IPv4 addresses, because the former retains the IPv4 to + IPv6 mapping prefix. + + --hh _h_o_m_e_d_i_r + overrides the default DCC home directory, _/_v_a_r_/_d_c_c. + + --II _u_s_e_r + specifies the UID and GID of the process. + + --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 + specifies the protocol and address by which sendmail will contact + ddccccmm. The default is a UNIX domain socket in the "run" directory, + _/_v_a_r_/_r_u_n_/_d_c_c_/_d_c_c_m. (See also --RR)) This protocol and address must + match the value in _s_e_n_d_m_a_i_l_._c_f. This mechanism can be used to con- + nect ddccccmm on one computer to sendmail on another computer when a + port and host name or IP address are used. + + --mm _m_a_p + specifies a name or path of the memory mapped parameter file instead + of the default _m_a_p file in the DCC home directory. It should be + created with the cdcc(8) command. + + --ww _w_h_i_t_e_c_l_n_t + specifies an optional file containing filtering parameters as well + as SMTP client IP addresses, SMTP envelope values, and header values + of mail that is spam or is not spam and does not need a _X_-_D_C_C + header, and whose checksums should not be reported to the DCC + server. + + If the pathname _w_h_i_t_e_c_l_n_t is not absolute, it is relative to the DCC + home directory. + + The format of the ddccccmm whiteclnt file is the same as the _w_h_i_t_e_l_i_s_t + files used by dbclean(8) and the _w_h_i_t_e_c_l_n_t file used by dccproc(8). + See dcc(8) for a description of DCC white and blacklists. Because + the contents of the _w_h_i_t_e_c_l_n_t file are used frequently, a companion + file is automatically created and maintained. It has the same path- + name but with an added suffix of _._d_c_c_w and contains a memory mapped + hash table of the main file. + + A whitelist entry ("OK") or two or more semi-whitelistings ("OK2") + for one of the message's checksums prevents all of the message's + checksums from being reported to the DCC server and the addition of + a _X_-_D_C_C header line by ddccccmm A whitelist entry for a checksum also + prevents rejecting or discarding the message based on DCC recipient + counts as specified by --aa and --tt. Otherwise, one or more checksums + with blacklisting entries ("MANY") cause all of the message's check- + sums to be reported to the server with an addressee count of "MANY". + + If the message has a single recipient, an _e_n_v___T_o _w_h_i_t_e_c_l_n_t entry of + "OK" for the checksum of its recipient address acts like any other + _w_h_i_t_e_c_l_n_t entry of "OK." When the SMTP message has more than one + recipient, the effects can be complicated. When a message has sev- + eral recipients with some but not all listed in the _w_h_i_t_e_c_l_n_t file, + ddccccmm tries comply with the wishes of the users who want filtering as + well as those who don't by silently not delivering the message to + those who want filtering (i.e. are not whitelisted) and delivering + the message to don't want filtering. + + --UU _u_s_e_r_d_i_r_s + enables per-user _w_h_i_t_e_c_l_n_t files and log directories. Each target + of a message can have a directory of log files named + _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 + macro described below. If _$_{_d_c_c___u_s_e_r_d_i_r_} is not set, + _u_s_e_r_d_i_r_s_/_$_{_r_c_p_t___m_a_i_l_e_r_}_/_$_{_r_c_p_t___a_d_d_r_}_/_l_o_g is used. The most likely + value of _m_a_i_l_e_r is _l_o_c_a_l. Appropriate values for both + _$_{_r_c_p_t___m_a_i_l_e_r_} and _$_{_r_c_p_t___a_d_d_r_} can be seen by examining _e_n_v___T_o + lines in --ll _l_o_g_d_i_r files. If it is not absolute, _u_s_e_r_d_i_r_s is rela- + tive to the DCC home directory. The directory containing the log + files must be named _l_o_g and it must be writable by the ddccccmm process. + Each log directory must exist or logging for the corresponding is + silently disabled. The files created in the log directory are owned + by the UID of the ddccccmm process, but they have _g_r_o_u_p and _o_t_h_e_r read + and write permissions copied from the corresponding _l_o_g directory. + To ensure the privacy of mail, it may be good to make the directo- + ries readable only by _o_w_n_e_r and _g_r_o_u_p, and to use a cron script that + changes the owner of each file to match the grandparent _a_d_d_r direc- + tory. + + There can also be a per -user whitelist file named + _u_s_e_r_d_i_r_s_/_$_{_d_c_c___u_s_e_r_d_i_r_}_/_w_h_i_t_e_c_l_n_t or if _$_{_d_c_c___u_s_e_r_d_i_r_} is not set, + _u_s_e_r_d_i_r_s_/_$_{_r_c_p_t___m_a_i_l_e_r_}_/_$_{_r_c_p_t___a_d_d_r_} per-user whitelist files. Any + checksum that is not white- or blacklisted by an individual + addressee's _w_h_i_t_e_c_l_n_t file is checked in the main --ww --wwhhiitteeccllnntt + file. A missing per-addressee _w_h_i_t_e_c_l_n_t file is the same as an + empty file. Relative paths for files included in per-addressee + files are resolved in the DCC home directory. The _w_h_i_t_e_c_l_n_t files + and the _a_d_d_r directories containing them must be writable by the + ddccccmm process. + + _O_p_t_i_o_n lines in per-user whiteclnt files can be used to modify many + aspects of ddccccmm filtering, as described in the main dcc man page. + For example, an _o_p_t_i_o_n _d_c_c_-_o_f_f line turns off DCC filtering for + individual mailboxes. + + --aa _I_G_N_O_R_E | _R_E_J_E_C_T | _D_I_S_C_A_R_D + specifies the action taken when DCC server counts or --tt thresholds + say that a message is unsolicited and bulk. _I_G_N_O_R_E causes the mes- + sage to be unaffected except for adding the _X_-_D_C_C header line to the + message. This turns off DCC filtering. + + Spam can also be _R_E_J_E_C_Ted or accepted and silently _D_I_S_C_A_R_Ded without + being delivered to local mailboxes. The default is _R_E_J_E_C_T. + + Mail forwarded via IP addresses marked _M_X or _M_X_D_C_C in the main + _w_h_i_t_e_c_l_n_t file is treated as if --aa _D_I_S_C_A_R_D were specified. This + prevents "bouncing" spam. + + Determinations that mail is or is not spam from sendmail via + _$_{_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 + the --ww _w_h_i_t_e_c_l_n_t are not affected by --aa. + + --tt _t_y_p_e_,[_l_o_g_-_t_h_o_l_d_,]_r_e_j_-_t_h_o_l_d + sets logging and "spam" thresholds for checksum _t_y_p_e. The checksum + 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, + _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 + _s_u_b_s_t_i_t_u_t_e, have no effect except when a local DCC server configured + with --KK is used. The _s_u_b_s_t_i_t_u_t_e thresholds apply to the first sub- + stitute heading encountered in the mail message. The string _A_L_L + sets thresholds for all types, but is unlikely to be useful except + for setting logging thresholds. The string _C_M_N specifies the com- + 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 + must be numbers, the string _N_E_V_E_R, or the string _M_A_N_Y indicating + millions of targets. Counts from the DCC server as large as the + threshold for any single type are taken as sufficient evidence that + the message should be logged or rejected. + + _L_o_g_-_t_h_o_l_d is the threshold at which messages are logged. It can be + handy to log messages at a lower threshold to find solicited bulk + mail sources such as mailing lists. If no logging threshold is set, + only rejected mail and messages with complicated combinations of + white and blacklisting are logged. Messages that reach at least one + of their rejection thresholds are logged regardless of logging + thresholds. + + _R_e_j_-_t_h_o_l_d is the threshold at which messages are considered "bulk," + and so should be rejected or discarded if not whitelisted. + + DCC Reputation thresholds in the commercial version of the DCC are + controlled by thresholds on checksum types _r_e_p and _r_e_p_-_t_o_t_a_l. Mes- + sages from an IP address that the DCC database says has sent more + than --tt _r_e_p_-_t_o_t_a_l_,_l_o_g_-_t_h_o_l_d messages are logged. A DCC Reputation + is computed for messages received from IP addresses that have sent + 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 + IP address is the percentage of its messages that have been detected + as bulk or having at least 10 recipients. The defaults are equiva- + 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. + + Bad DCC Reputations do not reject mail unless enabled by an _o_p_t_i_o_n + _D_C_C_-_r_e_p_-_o_n line in a _w_h_i_t_e_c_l_n_t file. + + The checksums of locally whitelisted messages are not checked with + the DCC server and so only the number of targets of the current copy + of a whitelisted message are compared against the thresholds. + + The default is _A_L_L_,_N_E_V_E_R, so that nothing is discarded, rejected, or + logged. A common choice is _C_M_N_,_2_5_,_5_0 to reject or discard mail with + common bodies except as overridden by the whitelist of the DCC + 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 + --gg, and --ww. + + --gg [_n_o_t_-]_t_y_p_e + indicates that whitelisted, _O_K or _O_K_2, counts from the DCC server + for a type of checksum are to be believed. They should be ignored + if prefixed with _n_o_t_-. _T_y_p_e is one of the same set of strings as + for --tt. Only _I_P, _e_n_v___F_r_o_m, and _F_r_o_m are likely choices. By default + all three are honored, and hence the need for _n_o_t_-. + + --SS _h_d_r + adds to the list of substitute or locally chosen headers that are + checked with the --ww _w_h_i_t_e_c_l_n_t file and sent to the DCC server. The + checksum of the last header of type _h_d_r found in the message is + checked. _H_d_r can be _H_E_L_O to specify the SMTP envelope HELO value. + _H_d_r can also be _m_a_i_l___h_o_s_t to specify the sendmail "resolved" host + name from the Mail_from value in the SMTP envelope. As many as six + different substitute headers can be specified, but only the checksum + of the first of the six will be sent to the DCC server. + + --ll _l_o_g_d_i_r + specifies a directory in which files containing copies of messages + processed by ddccccmm are kept. They can be copied to per-user directo- + ries specified with --UU. Information about other recipients of a + message is deleted from the per-user copies. + + See the FILES section below concerning the contents of the files. + 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 + _w_h_i_t_e_c_l_n_t files described in dcc(8). + + The directory is relative to the DCC home directory if it is not + absolute + + --RR _r_u_n_d_i_r + specifies the "run" directory where the UNIX domain socket and file + containing the daemon's process ID are stored. The default value is + /var/run/dcc . + + --rr _r_e_j_e_c_t_i_o_n_-_m_s_g + specifies the rejection message in --oo proxy mode for unsolicited + bulk mail or for mail temporarily blocked by _g_r_e_y_l_i_s_t_i_n_g when --GG is + specified. The first --rr _r_e_j_e_c_t_i_o_n_-_m_s_g replaces the default bulk + mail rejection message, "5.7.1 550 mail %ID from %CIP rejected by + DCC". The second replaces "4.2.1 452 mail %ID from %CIP temporary + greylist embargoed". The third --rr _r_e_j_e_c_t_i_o_n_-_m_s_g replaces the + default SMTP rejection message "5.7.1 550 %ID bad reputation; see + http://commercial-dcc.rhyolite.com/cgi-bin/reps.cgi?tgt=%CIP" for + mail with bad DCC Reputations. If _r_e_j_e_c_t_i_o_n_-_m_s_g is the zero-length + string, the --rr setting is counted but the corresponding message is + not changed. + + _R_e_j_e_c_t_i_o_n_-_m_s_g can contain specific information about the mail mes- + sage. The following strings starting with % are replaced with the + corresponding values: + %ID message ID such as the unique part of log file name or + sendmail queue ID + %CIP SMTP client IP address + %BTYPE type of DNS blacklist hit, such as "SMTP client", + "mail_host", or "URL NS" + %BTGT IP address or name declared bad by DNS blacklist + %BPROBE domain name found in DNS blacklist such as + 4.3.2.10.example.com + %BRESULT value of the %BPROBE domain name found in DNS black- + list + + A common alternate for the bulk mail rejection message is "4.7.1 451 + Access denied by DCC" to tell the sending mail system to continue + trying. Use a 4yz response with caution, because it is likely to + delay for days a delivery failure message for false positives. If + the rejection message does not start with an RFC 1893 status code + and RFC 2821 reply code, 5.7.1 and 550 or 4.2.1 and 452 are used. + + 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 + mail rejected by DNS blacklists. + + --jj _m_a_x_j_o_b_s + limits the number of simultaneous requests that will be processed. + The default value is the maximum number that seems to be possible + given system limits on open files, select() bit masks, and so forth. + Start ddccccmm with --dd and see the starting message in the system log to + see the limit. + + --BB _d_n_s_b_l_-_o_p_t_i_o_n + enables DNS blacklist checks of the SMTP client IP address, SMTP + envelope Mail_From sender domain name, and of host names in URLs in + the message body. Body URL blacklisting has too many false posi- + tives to use on abuse mailboxes. It is less effective than + greylisting with dccm(8) or dccifd(8) but can be useful in situa- + tions where greylisting cannot be used. + + _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 + --BB _d_o_m_a_i_n[_,_I_P_a_d_d_r[_/_x_x[_,_b_l_t_y_p_e]]] + _D_o_m_a_i_n is a DNS blacklist domain such as example.com that will be + searched. _I_P_a_d_d_r[_/_x_x_x] is the string "any" an IP address in the DNS + blacklist that indicates that the mail message should be rejected, + or a CIDR block covering results from the DNS blacklist. + "127.0.0.2" is assumed if _I_P_a_d_d_r is absent. IPv6 addresses can be + specified with the usual colon (:) notation. Names can be used + instead of numeric addresses. The type of DNS blacklist is speci- + 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 + domain name or a domain name in a URL of spam.domain.org and a + blacklist of type _n_a_m_e, spam.domain.org.example.com will be tried. + Blacklist types of _I_P_v_4 and _I_P_v_6 require that the domain name in a + URL sender address be resolved into an IPv4 or IPv6 address. The + address is then written as a reversed string of decimal octets to + check the DNS blacklist, as in 2.0.0.127.example.com, + + More than one blacklist can be specified and blacklists can be + grouped. All searching within a group is stopped at the first posi- + tive result. + + Positive results are ignored after being logged unless an + _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 + file. + + --BB _s_e_t_:_n_o_-_c_l_i_e_n_t + says that SMTP client IP addresses and reverse DNS domain names + should not be checked in the following blacklists. + --BB _s_e_t_:_c_l_i_e_n_t restores the default for the following black- + lists. + + --BB _s_e_t_:_n_o_-_m_a_i_l___h_o_s_t + says that SMTP envelope Mail_From sender domain names should + not be checked in the following blacklists. --BB _s_e_t_:_m_a_i_l___h_o_s_t + restores the default. + + --BB _s_e_t_:_n_o_-_U_R_L + says that URLs in the message body should not be checked in the + in the following blacklists. --BB _s_e_t_:_U_R_L restores the default. + + --BB _s_e_t_:_n_o_-_M_X + says MX servers of sender Mail_From domain names and host names + in URLs should not be checked in the following blacklists. + --BB _s_e_t_:_M_X restores the default. + + --BB _s_e_t_:_n_o_-_N_S + says DNS servers of sender Mail_From domain names and host + names in URLs should not be checked in the following black- + lists. --BB _s_e_t_:_N_S restores the default. + + --BB _s_e_t_:_d_e_f_a_u_l_t_s + 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 + --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 + + --BB _s_e_t_:_g_r_o_u_p_=_X + adds later DNS blacklists specified with + --BB _d_o_m_a_i_n[_,_I_P_a_d_d_r[_/_x_x[_,_b_l_t_y_p_e]]] + to group 1, 2, or 3. + + --BB _s_e_t_:_d_e_b_u_g_=_X + sets the DNS blacklist logging level + + --BB _s_e_t_:_m_s_g_-_s_e_c_s_=_S + limits ddccccmm to _S seconds total for checking all DNS blacklists. + The default is 25. + + --BB _s_e_t_:_U_R_L_-_s_e_c_s_=_S + limits ddccccmm to at most _S seconds resolving and checking any + single URL. The default is 11. Some spam contains dozens of + URLs and that some "spamvertised" URLs contain host names that + need minutes to resolve. Busy mail systems cannot afford to + spend minutes checking each incoming mail message. + + --BB _s_e_t_:_r_e_j_-_m_s_g_=_r_e_j_e_c_t_i_o_n_-_m_s_g + sets the SMTP rejection message for the following blacklists. + _R_e_j_e_c_t_i_o_n_-_m_s_g must be in the same format as for --rr. If + _r_e_j_e_c_t_i_o_n_-_m_s_g is null, the default is restored. The default + DNS blacklist rejection message is the first message set with + --rr. + + --BB _s_e_t_:_t_e_m_p_-_f_a_i_l + causes ddccccmm to the MTA to answer the SMTP DATA command with + 452 4.2.1 mail %ID from %CIP temporary delayed for DNSBL + if any DNS answer required for a DNSBL in the current group + times out, including resolving names in URLs. + + --BB _s_e_t_:_n_o_-_t_e_m_p_-_f_a_i_l + restores the default of assuming a negative answer for DNS + responses that take too long. + + --BB _s_e_t_:_m_a_x_j_o_b_s_=_X + sets maximum number of helper processes to _X. In order to use + typical single-threaded DNS resolver libraries, ddccccmm uses + fleets of helper processes. It is rarely a good idea to change + the default, which is the same as the maximum number of simul- + taneous jobs set with --jj. + + --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 + changes the path to the helper program. + + --LL _l_t_y_p_e_,_f_a_c_i_l_i_t_y_._l_e_v_e_l + specifies how messages should be logged. _L_t_y_p_e must be _e_r_r_o_r, _i_n_f_o, + or _o_f_f to indicate which of the two types of messages are being con- + trolled or to turn off all syslog(3) messages from ddccccmm. _L_e_v_e_l must + 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, + _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, + _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 + _L_O_C_A_L_7. The default is equivalent to + --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 + + ddccccmm normally sends counts of mail rejected and so forth the to system + log at midnight. The SIGUSR1 signal sends an immediate report to the + system log. They will be repeated every 24 hours instead of at midnight. + +SSEENNDDMMAAIILL MMAACCRROOSS + Sendmail can affect ddccccmm with the values of some _s_e_n_d_m_a_i_l_._c_f macros. + These macro names must be added to the Milter.macros option statements in + _s_e_n_d_m_a_i_l_._c_f as in the example "Feature" file dcc.m4. + + _$_{_d_c_c___i_s_s_p_a_m_} causes a mail message to be reported to the DCC server as + having been addressed to "MANY" recipients. The + _$_{_d_c_c___i_s_s_p_a_m_} macro is ignored if the _$_{_d_c_c___n_o_t_s_p_a_m_} macro + is set to a non-null string + + If the value of the _$_{_d_c_c___i_s_s_p_a_m_} is null, ddccccmm uses SMTP + rejection messages controlled by --aa and --rr. If the value + of the _$_{_d_c_c___i_s_s_p_a_m_} macro starts with "DISCARD", the mail + message is silently discarded as with --aa _D_I_S_C_A_R_D_. If value + of the macro not null and does not start with "DISCARD", + it is used as the SMTP error message given to the SMTP + client trying to send the rejected message. The message + starts with an optional SMTP error type and number fol- + lowed by text. + + The --aa option does not effect messages marked spam with + _$_{_d_c_c___i_s_s_p_a_m_}. When the _$_{_d_c_c___i_s_s_p_a_m_} macro is set, the + message is rejected or discarded despite local or DCC + database whitelist entries. The local whitelist does con- + trol whether the message's checksums will be reported to + the DCC server and an _X_-_D_C_C SMTP header line will be + added. + + _$_{_d_c_c___n_o_t_s_p_a_m_} + causes a message not be considered unsolicited bulk + despite evidence to the contrary. It also prevents ddccccmm + from reporting the checksums of the message to the DCC + server and from adding an _X_-_D_C_C header line. + + When the macro is set by the _s_e_n_d_m_a_i_l_._c_f rules, + _$_{_d_c_c___n_o_t_s_p_a_m_} macros overrides DCC threshlds that say the + message should be rejected as well as the effects of the + _$_{_d_c_c___i_s_s_p_a_m_} macro. + + _$_{_d_c_c___m_a_i_l___h_o_s_t_} + specifies the name of the SMTP client that is sending the + message. This macro is usually the same as the _m_a_i_l___h_o_s_t + macro. They can differ when a sendmail "smart relay" is + involved. The _$_{_d_c_c___m_a_i_l___h_o_s_t_} macro does not work if + _F_E_A_T_U_R_E_(_d_e_l_a_y___c_h_e_c_k_s_) is used. + + _$_{_d_c_c___u_s_e_r_d_i_r_} + is the per-user whitelist and log directory for a recipi- + ent. If the macro is not set in sendmail.cf, + $&{rcpt_mailer}/$&{rcpt_addr} is assumed, but with the + recipient address converted to lower case. Whatever value + is used, the directory name after the last slash (/) char- + acter is converted to lower case. Any value containing + the string "/../" is ignored. + + 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 + used. + + The following two lines in a sendmail mc file have the + same effect as not defining the ${dcc_userdir} macro, pro- + vided _F_E_A_T_U_R_E_(_d_c_c_) is also used and the sendmail + _c_f_/_f_e_a_t_u_r_e directory has a symbolic link to the + _m_i_s_c_/_d_c_c_._m_4 file. + + SLocal_check_rcpt + R$* $: $1 $(macro {dcc_userdir} $@ $&{rcpt_mailer}/$&{rcpt_addr} $)) + +FFIILLEESS + /var/dcc is the DCC home directory in which other files are found. + /var/dcc/libexec/start-dccm + is a script used to ddccccmm. + dcc/dcc_conf + contains parameters used by the scripts to start DCC daemons + and cron jobs. + logdir is an optional directory specified with --ll and containing + marked mail. Each file in the directory contains one message, + at least one of whose checksums reached its --tt thresholds or + that is interesting for some other reason. Each file starts + with lines containing the date when the message was received, + the IP address of the SMTP client, and SMTP envelope values. + Those lines are followed by the body of the SMTP message + including its header as it was received by sendmail and with- + out any new or changed header lines. Only approximately the + first 32 KBytes of the body are recorded unless modified by + _._/_c_o_n_f_i_g_u_r_e _-_-_w_i_t_h_-_m_a_x_-_l_o_g_-_s_i_z_e_=_x_x The checksums for the mes- + sage follow the body. They are followed by lines indicating + that the _$_{_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 + were set or one of the checksums is white- or blacklisted by + the --ww _w_h_i_t_e_c_l_n_t file. Each file ends with the _X_-_D_C_C header + line added to the message and the disposition of the message + including SMTP status message if appropriate. + map is the memory mapped file of information concerning DCC + servers in the DCC home directory. + whiteclnt contains the client whitelist in the format described in + dcc(8). + whiteclnt.dccw + is a memory mapped hash table of the _w_h_i_t_e_c_l_n_t file. + dccm.pid in the --RR _r_u_n_d_i_r directory contains daemon's process ID. The + string ``dccm'' is replaced by the file name containing the + daemon to facilitate running multiple daemons, probably con- + nected to remote instances of sendmail using TCP/IP instead of + a UNIX domain socket. See also --RR. + /var/run/dcc/dccm + is the default UNIX domain socket used by the sendmail milter + interface. See also --RR. + sendmail.cf + is the sendmail(8) control file. + misc/dcc.m4 + sendmail mc file that should have a symbolic link in the send- + mail cf/feature directory so that _F_E_A_T_U_R_E_(_d_c_c_) can be used in + a sendmail mc file. + +EEXXAAMMPPLLEESS + DDccccmm should be started before sendmail with something like the script + _/_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 + _d_c_c___c_o_n_f file in the DCC home directory, _/_v_a_r_/_d_c_c_. + + Those numbers should modified to fit local conditions. It might be wise + to replace the "100" numbers with much larger values or with "MANY" until + a few weeks of monitoring the log directory show that sources of mailing + lists are in the server's whitelist file (see dccd(8)) or the local + _w_h_i_t_e_c_l_n_t file. + + It is usually necessary to regularly delete old log files with a script + like /var/dcc/libexec/cron-dccd. + + On systems unlike modern FreeBSD and other UNIX-like systems which + include sendmail milter support, sendmail must be built with the milter + 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 + file containing something like the following lines: + + APPENDDEF(`conf_sendmail_ENVDEF', `-D_FFR_MILTER=1') + APPENDDEF(`conf_libmilter_ENVDEF', `-D_FFR_MILTER=1') + + Appropriate lines invoking the milter interface must be added to + _s_e_n_d_m_a_i_l_._c_f_. That can be done by putting a symbolic link to the the + misc/dcc.m4 file in the DCC source to the sendmail cf/feature directory + and adding the line + + FEATURE(dcc) + + to the local .mc file. + + Note that ddccccmm should not be used with the Postfix milter mechanism. + Instead use dccifd(8) as a before-queue filter as described in that man + page. + +SSEEEE AALLSSOO + cdcc(8), dbclean(8), dcc(8), dccd(8), dblist(8), dccifd(8), dccproc(8), + dccsight(8), sendmail(8). + +HHIISSTTOORRYY + Distributed Checksum Clearinghouses are based on an idea of Paul Vixie. + Implementation of ddccccmm was started at Rhyolite Software in 2000. This + document describes version 1.3.103. + +BBUUGGSS + ddccccmm uses --tt where dccproc(8) uses --cc. + + Systems without setrlimit(2) and getrlimit(2) RLIMIT_NOFILE can have + problems with the default limit on the number of simultaneous jobs, the + value of --jj. Every job requires four open files. These problems are + usually seen with errors messages that say something like + dccm[24448]: DCC: accept() returned invalid socket + A fix is to use a smaller value for --jj or to allow ddccccmm to open more + files. Sendmail version 8.13 and later can be told to poll() instead of + select with SM_CONF_POLL. Some older versions of sendmail knew about + FFR_USE_POLL. One of the following lines in your devtools/Site/site.con- + fig.m4 file can help: + + APPENDDEF(`conf_libmilter_ENVDEF', `-DSM_CONF_POLL') + APPENDDEF(`conf_libmilter_ENVDEF', `-DFFR_USE_POLL') + + On many systems with sendmail 8.11.3 and preceding, a bug in the sendmail + milter mechanism causes ddccccmm to die with a core file when given a signal. + + February 26, 2009