dccifd(8) System Manager's Manual dccifd(8)
ddcccciiffdd -- Distributed Checksum Clearinghouse Program Interface
ddcccciiffdd [--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]
[--pp _/_s_o_c_k | _h_o_s_t_,_p_o_r_t_,_r_h_o_s_t_/_b_i_t_s] [--oo _/_s_o_c_k | _h_o_s_t_,_p_o_r_t]
[--DD _l_o_c_a_l_-_d_o_m_a_i_n] [--rr _r_e_j_e_c_t_i_o_n_-_m_s_g] [--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] [--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] [--TT _t_m_p_d_i_r]
[--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]
DDcccciiffdd is a daemon intended to connect spam filters such as SpamAssasin
and mail transfer agents (MTAs) other than sendmail to DCC servers. The
MTA or filter ddcccciiffdd which in turn reports related checksums to the near-
est DCC server. DCCIFD then adds an _X_-_D_C_C SMTP header line to the mes-
sage. The MTA is told to reject the message if it is unsolicited bulk.
DDcccciiffdd is similar to the DCC sendmail milter interface, dccm(8) and the
DCC Procmail interface, dccproc(8). ddcccciiffdd is more efficient than
dccproc but not restricted to use with sendmail. All three send reports
of checksums related to mail received by DCC clients and queries about
the total number of reports of particular checksums.
MTA programs generally use a simple ASCII protocol to send a mail message
including its SMTP envelope to the daemon. DDcccciiffdd responds with an indi-
cation of whether the message is unsolicited bulk and an optional copy of
the message with an _X_-_D_C_C header added. The protocol is described below
and in the _i_n_c_l_u_d_e_/_d_c_c_i_f_._h file in the DCC source. There is a sample C
interface routine in the _d_c_c_l_i_b_/_d_c_c_i_f_._c file in the DCC source and the
_d_c_c_l_i_b_._a library generated from the source. A _P_e_r_l version of the inter-
face routine is in _d_c_c_i_f_d_/_d_c_c_i_f_._p_l. Test or demonstration programs in
the style of dccproc(8) that use those interface routines are in
A subset of ESMTP can be used instead of the ASCII protocol to connect
ddcccciiffdd to postfix as a "Before-Queue Content Filter." See the --oo flag.
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, ddcccciiffdd knows nothing
about the total recipient counts for their checksums and so cannot add
_X_-_D_C_C header lines to such messages.
The list of servers that ddcccciiffdd contacts is in a memory mapped file
shared by local DCC clients. The file is maintained with cdcc(8). Turn
on the daemon and put its parameters in the _d_c_c___c_o_n_f. Start the daemon
with the _s_t_a_r_t_-_d_c_c_i_f_d script.
The following options are available:
--VV displays the version of the DCC program interface.
--dd enables debugging output from the DCC client library. Additional --dd
options increase the number of messages. A single --dd causes aborted
SMTP transactions to be logged.
--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, ddcccciiffdd normally does not delay too long while trying
to contact a DCC server. It also 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
--QQ only queries the DCC server about the checksums of messages instead
of reporting and querying. This is useful when ddcccciiffdd is used to
filter mail that has already been reported to a DCC server by
another DCC client. This can also be useful when applying a private
white or black list to mail that has already been reported to a DCC
server. 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.
--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 DCC client pro-
cesses of dccm or dccifd should 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 because the former retains the IPv4 to IPv6 mapping pre-
--WW turns off DCC filtering by default to ease managing systems where
only a minority of users want unsolicited bulk mail to be rejected.
This is equivalent to a _o_p_t_i_o_n _d_c_c_-_o_f_f line in the main --ww _w_h_i_t_e_c_l_n_t
file. When DCC filtering is off, the DCC server is queried and the
_X_-_D_C_C header is added but the message is marked to be delivered
regardless of target counts and thresholds.
DCC filtering is enabled for a mailbox when --WW is not used and there
is no _o_p_t_i_o_n _d_c_c_-_o_f_f line in the main or per-user _w_h_i_t_e_c_l_n_t file or
there is a _o_p_t_i_o_n _d_c_c_-_o_n pine in the per-user _w_h_i_t_e_c_l_n_t file for the
mailbox. DCC filtering can also be enabled with an "OK2" entry for
the fully qualified mailbox in the main or per-user _w_h_i_t_e_c_l_n_t file.
Messages sent _o_n_l_y to target addresses that are listed in the global
or relevant per-user --ww _w_h_i_t_e_c_l_n_t file with "OK" are not reported to
the DCC server and so are not rejected and do not receive _X_-_D_C_C
overrides the default DCC home directory, which is often /var/dcc.
--pp _/_s_o_c_k_/_n_a_m_e | _h_o_s_t_,_p_o_r_t_,_r_h_o_s_t_/_b_i_t_s
overrides the default address at which programs contact ddcccciiffdd. The
default is a UNIX domain socket named dccifd in the DCC home direc-
The second form specifies a local host name or IP address, a local
TCP port number, and the host names or IP addresses of computers
that can use ddcccciiffdd. 127.0.0.1 or _l_o_c_a_l_h_o_s_t are common choices for
_h_o_s_t. The string _@ specifies IN_ADDRANY or all local IP addresses.
127.0.0.0/8 is a common choice for _r_h_o_s_t_/_b_i_t_s.
--oo _/_s_o_c_k | _h_o_s_t_,_p_o_r_t
enables SMTP proxy mode instead of the ASCII protocol and specifies
the address of the SMTP server for which ddcccciiffdd acts as SMTP client.
When _/_s_o_c_k is _/_v_a_r_/_n_u_l_l, ddcccciiffdd acts as if there were downstream
SMTP server that always answers "250 ok". The string _@ specifies
the same IP address as the incoming TCP connection.
See below concerning the subset of ESMTP used in this mode.
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 cdcc(8) command.
specifies an optional file containing SMTP client IP addresses, SMTP
envelope values, and header values of mail that is not spam, does
not need a X-DCC header, and whose checksums should not be reported
to the DCC server. Local whitelist _e_n_v___T_o values are handy for
whitelisting or exempting destination addresses such as Postmaster
from filtering and for blacklisting or marking addresses that should
never receive mail. Mail sent to blacklisted addresses or with
other blacklisted values such as From or env_From values is reported
to the DCC server as spam or with target counts of millions.
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 ddcccciiffdd 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 main-
tained. It has the same pathname but with an added suffix of _._d_c_c_w
and contains a memory mapped hash table of the main file.
A local whitelist entry ("OK") or two or more semi-white listings
("OK2") for one of the message's checksums prevents all of the mes-
sage's checksums from being reported to the DCC server and the addi-
tion of a _X_-_D_C_C header line by ddcccciiffdd (except for env_To checksums
or when --WW is used). A local whitelist entry for a checksum also
prevents rejecting the message based on DCC recipient counts as
specified by --tt. Otherwise, one or more checksums with blacklisting
entries ("MANY") cause all of the message's checksums 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 local _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 several recipients with some but not all listed in the _w_h_i_t_e_c_l_n_t
file, ddcccciiffdd tries comply with the wishes of the users who want fil-
tering 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.
Consider the --WW option for implicitly or by default whitelisting
enables private whitelists and log files. Each target of a message
can have a directory of log files named _u_s_e_r_d_i_r_s_/_a_d_d_r_/_l_o_g where _a_d_d_r
is the local user or mailbox name computed by the MTA. The name of
each user's log directory must be _l_o_g. If it is not absolute,
_u_s_e_r_d_i_r_s is relative to the DCC home directory. The sub-directory
prefixes for --ll _l_o_g_d_i_r are not honored. The directory containing
the log files must be named _l_o_g and it must be writable by the
ddcccciiffdd 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 ddcccciiffdd process, but they have
_g_r_o_u_p and _o_t_h_e_r read and write permissions copied from the corre-
sponding _l_o_g directory. To ensure the privacy of mail, it may be
good to make the directories 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 directory.
There can also be a whitelist named _u_s_e_r_d_i_r_s_/_a_d_d_r_/_w_h_i_t_e_c_l_n_t for each
address _a_d_d_r_. The name of the file must be _w_h_i_t_e_c_l_n_t. Any checksum
that is not white- or blacklisted by an individual addressee's
whitelist is checked in the --ww --wwhhiitteeccllnntt list. A missing per-
address _w_h_i_t_e_c_l_n_t file is the same as an empty file. Relative paths
for whitelists included in per-address 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 con-
taining them must be writable by the ddcccciiffdd process.
--aa _I_G_N_O_R_E | _R_E_J_E_C_T
specifies the action taken when ddcccciiffdd is in proxy mode with --oo and
the DCC server counts or --tt thresholds say that a message is unso-
licited bulk. _I_G_N_O_R_E causes the message to be unaffected except for
adding the _X_-_D_C_C header line to the message. This turns off DCC
Spam can also be _R_E_J_E_C_Ted. The default is _R_E_J_E_C_T.
With an action of _R_E_J_E_C_T, spam sent to both white-listed targets and
non-white-listed targets is delivered to white-listed targets and if
possible, silently discarded for non-white-listed targets. This is
not possible if there are too many non-white-listed targets to be
saved in a buffer of about 500 bytes.
The effects of the --ww _w_h_i_t_e_c_l_n_t are not affected by --aa.
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, _R_e_c_e_i_v_e_d, _B_o_d_y, _F_u_z_1, and
_F_u_z_2. 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 commonly 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
_R_e_j_-_t_h_o_l_d is the threshold at which messages are considered "bulk,"
and so should be rejected if not whitelisted.
The checksums of locally whitelisted messages are not checked with
the DCC server and so only the number of targets of the current
instance of a whitelisted message are compared against the thresh-
The default is --tt _A_L_L_,_N_E_V_E_R, so that nothing is rejected or logged.
A common choice is --tt _C_M_N_,_2_5_,_5_0 to reject mail with common bodies
except as overridden by the whitelist of the DCC server and local
--gg, and --ww.
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_-.
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 host name from the
Mail_from value in the SMTP envelope. As many as 6 different sub-
stitute headers can be specified, but only the checksum of the first
of the 6 will be sent to the DCC server.
specifies a directory in which files containing copies of messages
processed by ddcccciiffdd are kept. All messages logged are copied to the
--ll _l_o_g_d_i_r directory. They can also be copied to per-user directo-
ries specified with --UU. Information about other recipients of a
message is deleted from the per-user copies.
If _l_o_g_d_i_r starts with _D_?, log files are put into subdirectories of
the form _l_o_g_d_i_r_/_J_J_J where _J_J_J is the current julian day. _H_?_l_o_g_d_i_r
puts logs files into subdirectories of the form _l_o_g_d_i_r_/_J_J_J_/_H_H where
_H_H is the current hour. _M_?_l_o_g_d_i_r puts log files into subdirectories
of the form _l_o_g_d_i_r_/_J_J_J_/_H_H_/_M_M where _M_M is the current minute. See
the FILES section below concerning the contents of the files.
The directory is relative to the DCC home directory if it is not
specifies the "run" directory where the UNIX domain socket and file
containing the daemon's process ID are stored. The default value is
changes the default directory for temporary files from the default.
The default is the directory specified with --ll or the system default
if there --ll is not used. The system default is often _/_t_m_p.
specifies a host name by which the system is known. There can be
several --DD settings.
To find the per-user log directory and whitelist for each mail
recipient, ddcccciiffdd must know each recipient's user name. The default
ASCII protocol includes an optional user name with each recipient
SMTP address. When that user name is absent or when the subset of
ESMTP enabled with --oo is used, each mail address is checked against
the list of --DD _l_o_c_a_l_-_d_o_m_a_i_n_s. If there is at least one match, the
part of the recipient address remaining after matching the longest
_l_o_c_a_l_-_d_o_m_a_i_n is taken as the user name. The matching is anchored at
the right or the end of the recipient address. It must start at a
period (.) or at-sign (@) in the domain name part of the address.
specifies the rejection message 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 _r_e_j_e_c_t_i_o_n_-_m_s_g replaces the default bulk mail rejection mes-
sage, "5.7.1 550 mail %s from %s rejected by DCC" The second
replaces "4.2.1 452 mail %s from %s greylist temporary embargoed".
There can be zero, one, or two "%s" strings. The first is replaced
an empty string and the second is replaced by the IP address of the
A common alternate for the bulk mail rejection message is "4.7.1 451
Access denied by DCC" to tell the sender 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 bulk mail
rejection message does not start with a recognized error type and
number, type 5.7.1 and 550 or 4.2.1 and 452 are used.
limits the number of simultaneous requests that will be processed.
The default value is the maximum number that seems to be possible
given the number of open files, select() bit masks, and so forth
that are available.
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 far too many false pos-
itives 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 of the form _s_e_t_:_o_p_t_i_o_n or of the form
_d_o_m_a_i_n[_,_I_P_a_d_d_r[_,_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 is the IP address in the
DNS blacklist that indicates that the mail message is spam.
127.0.0.1 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 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 22.214.171.124.example.com,
More than one blacklist can be specified. They are searched in
order. All searching is stopped at the first positive result. Pos-
itive 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_:_d_e_b_u_g sends more messages about all DNS resolutions to the
--BB _s_e_t_:_m_s_g_-_s_e_c_s_=_S limits ddcccciiffdd to _S seconds total for checking all
DNS blacklists. The default is 20.
--BB _s_e_t_:_U_R_L_-_s_e_c_s_=_S limits ddcccciiffdd to at most _S seconds resolving and
checking any single URL. The default is 5. 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. In order to use
typical single-threaded DNS resolver libraries, dccm(8) and
dccifd(8) use fleets of helper processes.
--BB _s_e_t_:_n_o_-_e_n_v_e_l_o_p_e says that SMTP client IP addresses and sender
Mail_From domain names should not be checked in the following black-
lists. --BB _s_e_t_:_e_n_v_e_l_o_p_e restores the default for subsequently named
--BB _s_e_t_:_n_o_-_b_o_d_y says that URLs in the message body should not be
checked in the in the following blacklists. --BB _s_e_t_:_b_o_d_y restores
the default for later blacklists.
--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 black-
lists. --BB _s_e_t_:_M_X restores the default.
specifies how messages should be logged. _L_t_y_p_e must be _e_r_r_o_r or
_i_n_f_o to indicate which of the two types of messages are being con-
trolled. _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
ddcccciiffdd normally sends counts of mail rejected and so forth the system log
at midnight. The SIGUSR1 signal sends an immediate report to the system
log. The reports will be repeated every 24 hours at the same minute as
the signal instead of at midnight.
DDcccciiffdd uses a simple ASCII protocol to receive mail messages to be
checked and to return results. For each message, the MTA must open a
connection to the interface daemon, send options, envelope recipients,
and the message, receive the results, and close the connection.
Instead of the ASCII protocol, a subset of ESMTP is enabled by --oo. Only
the familiar HELO, EHLO, Mail, Rcpt, DATA, RSET, and QUIT commands and
the Postfix extensions XFORWARD and XCLIENT are honored. Since SMTP has
no provisions for user names, the protocol enabled by --oo depends on a
list of local domain names specified with --DD to find per-user log direc-
tories and whitelist files. If neither XFORWARD nor XCLIENT are used,
ddcccciiffdd uses the IP address of the MTA and the value of the HELO command.
In the ASCII protocol, each of the following lines are sent in order to
ddcccciiffdd. Each ends with a newline ('\n') character.
options zero or more blank-separated strings among:
_s_p_a_m the message is already known to be spam
_b_o_d_y return all of the headers with the added
_X_-_D_C_C header line and the body
_h_e_a_d_e_r return the _X_-_D_C_C header
_q_u_e_r_y ask the DCC server about the message without
reporting it as if ddcccciiffdd were running with
_g_r_e_y_-_q_u_e_r_y only query the greylist server for this mes-
sage. --GG _o_n must be in use.
_n_o_-_r_e_j_e_c_t suppress the overall, one character line 'R'
result. This can be useful when using ddcccciiffdd
only for greylisting.
client IP address of the SMTP client in a "dotted" or "coloned"
ASCII string and reverse-DNS host name. If the host name
is present, it must follow a carriage return character
('\r') after the IP address. The client IP address must be
present and non-null if the host name is present. If the
client IP address is absent, then the IP address and host
name are taken from the first Received header if it has the
standard "name (name [IP address])..." format.
HELO SMTP HELO value or nothing, followed by a newline charac-
sender or SMTP _M_a_i_l _F_r_o_m command value
recipients or SMTP _R_c_p_t _T_o values followed by corresponding local user
names, one pair to a line. Each optional local user name
is separated from the corresponding recipient address by a
carriage return ('\r'). A local user name can be null if
it is not known. Recipients that lack local user names
will lack per-user log files and will not invoke a per-user
The last recipient-user name pair is followed by an empty line and the
headers and body of the message. The end of the body of the mail message
is signaled by the MTA half-closing the connection. See shutdown(2).
DDcccciiffdd responds with three things. First is a one character line of the
overall result advising the MTA to
A accept the message for all recipients and answer the SMTP DATA
command with a 2yz result.
G answer with a 4yz result to embargo the message for greylisting.
R reject the message and answer the DATA command with a 5yz result.
S accept the message for some recipients and so answer the DATA com-
mand with a 2yz result.
T temporary failure by the DCC system and so answer with a 4yz
Second is a line of 'A', 'G', and 'R' characters indicating that the mes-
sage should be accepted and delivered or discarded for each corresponding
recipient. Limitations in the SMTP protocol allows only a single result
for the DATA command for all recipients that were not rejected before
body of the message was offered with the DATA command. To accept the
message for some recipients and reject it for others, the MTA must tell
the SMTP client it is accepting the message for all recipients and then
discard it for those that would reject it.
Finally, if the _b_o_d_y or _h_e_a_d_e_r strings are in the first line of _o_p_t_i_o_n_s
sent by the MTA to the daemon, then the _X_-_D_C_C header line or the entire
body with the _X_-_D_C_C header line follows.
/var/dcc is the DCC home directory in which other files are found.
is a script often used to the daemon.
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 mes-
sage, at least one of whose checksums reached its --tt thresh-
olds 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 enve-
lope values. Those lines are followed by the body of the
SMTP message including its header as it was received. 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 message follow the body. They are followed
by lines indicate that 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 disposi-
tion of the message.
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
is a memory mapped hash table of the _w_h_i_t_e_c_l_n_t file.
dccifd.pid in the --RR _r_u_n_d_i_r directory contains daemon's process ID.
cdcc(8), dbclean(8), dcc(8), dccd(8), dblist(8), dccm(8), dccproc(8),
Implementation of ddcccciiffdd was started at Rhyolite Software in 2002. This
describes version 1.2.74.
ddcccciiffdd uses --tt where dccproc(8) uses --cc.
Systems without setrlimit(2) and getrlimit(2) 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
dccifd: DCC: accept() returned invalid socket
A fix is to use a smaller value for --jj or to allow ddcccciiffdd to open more
FreeBSD 4.9 March 20, 2005 FreeBSD 4.9