dccproc(8)            Distributed Checksum Clearinghouse            dccproc(8)

NNAAMMEE
     ddccccpprroocc -- Distributed Checksum Clearinghouse Procmail Interface

SSYYNNOOPPSSIISS
     ddccccpprroocc [--VVddAAQQCCHHEERR] [--hh _h_o_m_e_d_i_r] [--mm _m_a_p] [--ww _w_h_i_t_e_c_l_n_t] [--TT _t_m_p_d_i_r]
             [--aa _I_P_-_a_d_d_r_e_s_s] [--ff _e_n_v___f_r_o_m] [--tt _t_a_r_g_e_t_s] [--xx _e_x_i_t_c_o_d_e]
             [--cc _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]
             [--ii _i_n_f_i_l_e] [--oo _o_u_t_f_i_l_e] [--ll _l_o_g_d_i_r] [--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
     DDccccpprroocc copies a complete SMTP message from standard input or a file to
     standard output or another file.  As it copies the message, it computes
     the DCC checksums for the message, reports them to a DCC server, and adds
     a header line to the message.  Another program such as procmail(1) can
     use the added header line to filter mail.  Dccproc does not support any
     thresholds of its own, because equivalent effects can be achieved with
     regular expressions and you can apply dccproc several times using differ-
     ent DCC servers and then score mail based what all of the DCC servers
     say.

     Error messages are sent to stderr as well as the system log.  Connect
     stderr and stdout to the same file to see errors in context, but direct
     stderr to /dev/null to keep DCC error messages out of the mail.  The --ii
     option can also be used to separate the error messages.

     DDccccpprroocc 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 no mail, address, headers, or other
     information, but only cryptographically secure checksums of such informa-
     tion.  A DCC server cannot determine the text or other information that
     corresponds to the checksums it receives.  It only acts as a clearing-
     house of counts of checksums computed by clients.

     For the sake of privacy for even the checksums of private mail, the
     checksums of senders 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.

     When sendmail(8) is used, dccm(8) is a better DCC interface.  Dccifd(8)
     is more efficient than ddccccpprroocc because it is a daemon, but that has costs
     in complexity.  See dccsight(8) for a way to use previously computed
     checksums.

   OOPPTTIIOONNSS
     The following options are available:

     --VV   displays the version of the DCC procmail(1) interface.

     --dd   enables debugging output from the DCC client software.  Additional
          --dd options increase the number of messages.  One causes error mes-
          sages to be sent to STDERR as well as the system log.

     --AA   adds to existing X-DCC headers (if any) of the brand of the current
          server instead of replacing existing headers.

     --QQ   only queries the DCC server about the checksums of messages instead
          of reporting and then querying.  This is useful when ddccccpprroocc is used
          to filter mail that has already been reported to a DCC server by
          another DCC client such as dccm(8).  No single mail message should
          be reported to a DCC server more than once per recipient.

          It is better to use _M_X_D_C_C lines in the --ww _w_h_i_t_e_c_l_n_t file for your MX
          mail servers that use DCC than --QQ

     --CC   outputs only the X-DCC header and the checksums for the message.

     --HH   outputs only the X-DCC header.

     --EE   adds lines to the start of the log file turned on with --ll and --cc
          describing what might have been the envelope of the message.  The
          information for the inferred envelope comes from arguments including
          --aa and headers in the message when --RR is used.  No lines are gener-
          ated for which no information is available, such as the envelope
          recipient.

     --RR   says the first Received lines have the standard
          "helo (name [address])..."  format and the address is that of the
          SMTP client that would otherwise be provided with --aa.  The --aa option
          should be used if the local SMTP server adds a Received line with
          some other format or does not add a Received line.  Received headers
          specifying IP addresses marked _M_X or _M_X_D_C_C in the --ww _w_h_i_t_e_c_l_n_t file
          are skipped.

     --hh _h_o_m_e_d_i_r
          overrides the default DCC home directory, _/_v_a_r_/_d_c_c.

     --mm _m_a_p
          specifies a name or path of the memory mapped parameter file instead
          of the default _m_a_p in the DCC home directory.  It should be created
          with the nneeww mmaapp operation of the cdcc(8) command.

     --ww _w_h_i_t_e_c_l_n_t
          specifies an optional file containing SMTP client IP addresses and
          SMTP headers of mail that do not need X-DCC headers and whose check-
          sums should not be reported to the DCC server.  It can also contain
          checksums of spam.  If the pathname is not absolute, it is relative
          to the DCC home directory.  Thus, individual users with private
          whitelists usually specify them with absolute paths.  Common
          whitelists shared by users must be in the DCC home directory or one
          of its subdirectories and owned by the set-UID user of ddccccpprroocc.  It
          is useful to _i_n_c_l_u_d_e a common or system-wide whitelist in private
          lists.

          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 pathname but with an added suffix of _._d_c_c_w.  It contains a mem-
          ory mapped hash table of the main file.

          _O_p_t_i_o_n lines can be used to modify many aspects of ddccccpprroocc filter-
          ing, as described in the main dcc(8) man page.  For example, an
          _o_p_t_i_o_n _s_p_a_m_-_t_r_a_p_-_a_c_c_e_p_t line turns off DCC filtering and reports the
          message as spam.

     --TT _t_m_p_d_i_r
          changes the default directory for temporary files from the system
          default.  The system default is _/_t_m_p.

     --aa _I_P_-_a_d_d_r_e_s_s
          specifies the IP address (not the host name) of the immediately pre-
          vious SMTP client.  It is often not available.  --aa _0_._0_._0_._0 is
          ignored.  --aa.  The --aa option should be used instead of --RR if the
          local SMTP server adds a Received line with some other format or
          does not add a Received line.

     --ff _e_n_v___f_r_o_m
          specifies the RFC 821 envelope "Mail From" value with which the mes-
          sage arrived.  It is often not available.  If --ff is not present, the
          contents of the first Return-Path: or UNIX style From_ header is
          used.  The _e_n_v___f_r_o_m string is often but need not be bracketed with
          "<>".

     --tt _t_a_r_g_e_t_s
          specifies the number of addressees of the message if other than 1.
          The string _m_a_n_y instead of a number asserts that there were too many
          addressees and that the message is unsolicited bulk email.

     --xx _e_x_i_t_c_o_d_e
          specifies the code or status with which ddccccpprroocc exits if the --cc
          thresholds are reached or the --ww _w_h_i_t_e_c_l_n_t file blacklists the mes-
          sage.

          The default value is EX_NOUSER.  EX_NOUSER is 67 on many systems.
          Use 0 to always exit successfully.

     --cc _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 --cc.  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.  As many as 6 different substitute headers can be speci-
          fied, but only the checksum of the first of the 6 will be sent to
          the DCC server.

     --ii _i_n_f_i_l_e
          specifies an input file for the entire message instead of standard
          input.  If not absolute, the pathname is interpreted relative to the
          directory in which ddccccpprroocc was started.

     --oo _o_u_t_f_i_l_e
          specifies an output file for the entire message including headers
          instead of standard output.  If not absolute, the pathname is inter-
          preted relative to the directory in which ddccccpprroocc was started.

     --ll _l_o_g_d_i_r
          specifies a directory for copies of messages whose checksum target
          counts exceed --cc thresholds.  The format of each file is affected by
          --EE.

          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

     --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.

          Unlike dccm(8) and dccifd(8), no _o_p_t_i_o_n _D_N_S_B_L_-_o_n line is required in
          the _w_h_i_t_e_c_l_n_t file.  A --BB argument is sufficient to show that DNSBL
          filtering is wanted by the ddccccpprroocc user.

          --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 ddccccpprroocc to _S seconds total for checking all DNS black-
               lists.  The default is 25.

          --BB _s_e_t_:_U_R_L_-_s_e_c_s_=_S
               limits ddccccpprroocc 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.

     --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 ddccccpprroocc.  _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

     ddccccpprroocc exits with 0 on success and with the --xx value if the --cc thresh-
     olds are reached or the --ww _w_h_i_t_e_c_l_n_t file blacklists the message.  If at
     all possible, the input mail message is output to standard output or the
     --oo _o_u_t_f_i_l_e despite errors.  If possible, error messages are put into the
     system log instead of being mixed with the output mail message.  The exit
     status is zero for errors so that the mail message will not be rejected.

     If ddccccpprroocc is run more than 500 times in fewer than 5000 seconds, ddccccpprroocc
     tries to start Dccifd(8).  The attempt is made at most once per hour.
     Dccifd is significantly more efficient than ddccccpprroocc.  With luck, mecha-
     nisms such as SpamAssassin will notice when dccifd is running and switch
     to dccifd.

FFIILLEESS
     /var/dcc   DCC home directory in which other files are found.
     map        memory mapped file in the DCC home directory of information
                concerning DCC servers.
     whiteclnt  contains the client whitelist in the format described in
                dcc(8).
     whiteclnt.dccw
                is a memory mapped hash table corresponding to the _w_h_i_t_e_c_l_n_t
                file.
     tmpdir     contains temporary files created and deleted as ddccccpprroocc pro-
                cesses the message.
     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 one of its --cc thresh-
                olds.  The entire body of the SMTP message including its
                header is followed by the checksums for the message.

EEXXAAMMPPLLEESS
     The following procmailrc(5) rule adds an X-DCC header to passing mail

         :0 f
         | /usr/local/bin/dccproc -ERw whiteclnt

     This procmailrc(5) recipe rejects mail with total counts of 10 or larger
     for the commonly used checksums:

         :0 fW
         | /usr/local/bin/dccproc -ERw whiteclnt -ccmn,10
         :0 e
         {
             EXITCODE=67
             :0
             /dev/null
         }

SSEEEE AALLSSOO
     cdcc(8), dcc(8), dbclean(8), dccd(8), dblist(8), dccifd(8), dccm(8),
     dccsight(8), mail(1), procmail(1).

HHIISSTTOORRYY
     Distributed Checksum Clearinghouses are based on an idea of Paul Vixie.
     Implementation of ddccccpprroocc was started at Rhyolite Software in 2000.  This
     document describes version 1.3.103.

BBUUGGSS
     ddccccpprroocc uses --cc where dccm(8) uses --tt.

                               February 26, 2009