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<!-- Manpage converted by man2html 3.0.1 -->
<B><A HREF="dccproc.html">dccproc(8)</A></B> Distributed Checksum Clearinghouse <B><A HREF="dccproc.html">dccproc(8)</A></B>
</PRE>
<H2><A NAME="NAME">NAME</A></H2><PRE>
<B>dccproc</B> -- Distributed Checksum Clearinghouse Procmail Interface
</PRE>
<H2><A NAME="SYNOPSIS">SYNOPSIS</A></H2><PRE>
<B>dccproc</B> [<B>-VdAQCHER</B>] [<B>-h</B> <I>homedir</I>] [<B>-m</B> <I>map</I>] [<B>-w</B> <I>whiteclnt</I>] [<B>-T</B> <I>tmpdir</I>]
[<B>-a</B> <I>IP-address</I>] [<B>-f</B> <I>env</I><B>_</B><I>from</I>] [<B>-t</B> <I>targets</I>] [<B>-x</B> <I>exitcode</I>]
[<B>-c</B> <I>type,</I>[<I>log-thold,</I>]<I>rej-thold</I>] [<B>-g</B> [<I>not-</I>]<I>type</I>] [<B>-S</B> <I>header</I>]
[<B>-i</B> <I>infile</I>] [<B>-o</B> <I>outfile</I>] [<B>-l</B> <I>logdir</I>] [<B>-B</B> <I>dnsbl-option</I>]
[<B>-L</B> <I>ltype,facility.level</I>]
</PRE>
<H2><A NAME="DESCRIPTION">DESCRIPTION</A></H2><PRE>
<B>Dccproc</B> is a low performance DCC client for checking single mail messages
for mail filters such as <B>procmail(1)</B>
<B>Dccproc</B> 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 <B>procmail(1)</B> can
use the added header line to filter mail or the exit <B>dccproc</B> exit status.
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 <B>-i</B>
option can also be used to separate the error messages.
<B>Dccproc</B> 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.
The checksums of private mail, the internal mail,and other mail that is
known to not be unsolicited bulk can be listed in a whitelist specified
with
When <B>sendmail(8)</B> is used, <B><A HREF="dccm.html">dccm(8)</A></B> is a better DCC interface. <B><A HREF="dccifd.html">Dccifd(8)</A></B>
is more efficient than <B>dccproc</B> because it is a daemon, but that has costs
in complexity. See <B><A HREF="dccsight.html">dccsight(8)</A></B> for a way to use previously computed
checksums.
<A NAME="OPTIONS"><B>OPTIONS</B></A>
The following options are available:
<A NAME="OPTION-V"><B>-V</B></A> displays the program's version.
<A NAME="OPTION-d"><B>-d</B></A> enables debugging output from the DCC client software. Additional
<B>-d</B> options increase the number of messages. One causes error mes-
sages to be sent to STDERR as well as the system log.
<A NAME="OPTION-A"><B>-A</B></A> adds to existing X-DCC headers (if any) of the brand of the current
server instead of replacing existing headers.
<A NAME="OPTION-Q"><B>-Q</B></A> only queries the DCC server about the checksums of messages instead
of reporting and then querying. This is useful when <B>dccproc</B> is used
to filter mail that has already been reported to a DCC server by
another DCC client such as <B><A HREF="dccm.html">dccm(8)</A></B>. No single mail message should
be reported to a DCC server more than once per recipient.
It is better to use <I>MXDCC</I> lines in the <B>-w</B> <I>whiteclnt</I> file for your MX
mail servers that use DCC than <B>-Q</B>
<A NAME="OPTION-C"><B>-C</B></A> outputs only the X-DCC header and the checksums for the message.
<A NAME="OPTION-H"><B>-H</B></A> outputs only the X-DCC header.
<A NAME="OPTION-E"><B>-E</B></A> adds lines to the start of the log file turned on with <B>-l</B> and <B>-c</B>
describing what might have been the envelope of the message. The
information for the inferred envelope comes from arguments including
<B>-a</B> and headers in the message when <B>-R</B> is used. No lines are gener-
ated for which no information is available, such as the envelope
recipient.
<A NAME="OPTION-R"><B>-R</B></A> 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 <B>-a</B>. The <B>-a</B> 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 <I>MX</I> or <I>MXDCC</I> in the <B>-w</B> <I>whiteclnt</I> file
are skipped.
<A NAME="OPTION-h"><B>-h</B></A> <I>homedir</I>
overrides the default DCC home directory, <I>/var/lib/dcc</I>.
<A NAME="OPTION-m"><B>-m</B></A> <I>map</I>
specifies a name or path of the memory mapped parameter file instead
of the default <I>map</I> in the DCC home directory. It should be created
with the <B>new map</B> operation of the <B><A HREF="cdcc.html">cdcc(8)</A></B> command.
<A NAME="OPTION-w"><B>-w</B></A> <I>whiteclnt</I>
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 <B>dccproc</B>. It
is useful to <I>include</I> a common or system-wide whitelist in private
lists.
Because the contents of the <I>whiteclnt</I> file are used frequently, a
companion file is automatically created and maintained. It has the
same pathname but with an added suffix of <I>.dccw</I>. It contains a mem-
ory mapped hash table of the main file.
<I>Option</I> lines can be used to modify many aspects of <B>dccproc</B> filter-
ing, as described in the main <B><A HREF="dcc.html">dcc(8)</A></B> man page. For example, an
<I>option</I> <I>spam-trap-accept</I> line turns off DCC filtering and reports the
message as spam.
<A NAME="OPTION-T"><B>-T</B></A> <I>tmpdir</I>
changes the default directory for temporary files from the system
default. The system default is <I>/tmp</I>.
<A NAME="OPTION-a"><B>-a</B></A> <I>IP-address</I>
specifies the IP address (not the host name) of the immediately pre-
vious SMTP client. It is often not available. <B>-a</B> <I>0.0.0.0</I> is
ignored. <B>-a</B>. The <B>-a</B> option should be used instead of <B>-R</B> if the
local SMTP server adds a Received line with some other format or
does not add a Received line.
<A NAME="OPTION-f"><B>-f</B></A> <I>env</I><B>_</B><I>from</I>
specifies the RFC 821 envelope "Mail From" value with which the mes-
sage arrived. It is often not available. If <B>-f</B> is not present, the
contents of the first Return-Path: or UNIX style From_ header is
used. The <I>env</I><B>_</B><I>from</I> string is often but need not be bracketed with
"<>".
<A NAME="OPTION-t"><B>-t</B></A> <I>targets</I>
specifies the number of addressees of the message if other than 1.
The string <I>many</I> instead of a number asserts that there were too many
addressees and that the message is unsolicited bulk email.
<A NAME="OPTION-x"><B>-x</B></A> <I>exitcode</I>
specifies the code or status with which <B>dccproc</B> exits if the <B>-c</B>
thresholds are reached or the <B>-w</B> <I>whiteclnt</I> file blacklists the mes-
sage.
The default value is EX_NOUSER. EX_NOUSER is 67 on many systems.
Use 0 to always exit successfully.
<A NAME="OPTION-c"><B>-c</B></A> <I>type,</I>[<I>log-thold,</I>]<I>rej-thold</I>
sets logging and "spam" thresholds for checksum <I>type</I>. The checksum
types are <I>IP</I>, <I>env</I><B>_</B><I>From</I>, <I>From</I>, <I>Message-ID</I>, <I>substitute</I>, <I>Received</I>,
<I>Body</I>, <I>Fuz1</I>, <I>Fuz2</I>, <I>rep-total</I>, and <I>rep</I>. The first six, <I>IP</I> through
<I>substitute</I>, have no effect except when a local DCC server configured
with <B>-K</B> is used. The <I>substitute</I> thresholds apply to the first sub-
stitute heading encountered in the mail message. The string <I>ALL</I>
sets thresholds for all types, but is unlikely to be useful except
for setting logging thresholds. The string <I>CMN</I> specifies the com-
monly used checksums <I>Body</I>, <I>Fuz1</I>, and <I>Fuz2</I>. <I>Rej-thold</I> and <I>log-thold</I>
must be numbers, the string <I>NEVER</I>, or the string <I>MANY</I> 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.
<I>Log-thold</I> 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.
<I>Rej-thold</I> 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 DCC are con-
trolled by thresholds on checksum types <I>rep</I> and <I>rep-total</I>. The DCC
Reputations of IP addresses that the DCC database says have sent
more than <I>rep-total,log-thold</I> are computed and messages from those
addresses are logged. Messages from IP addresses with DCC Reputa-
tions of at least the <I>rep,rej-thold</I> rejection threshold can be
rejected. The DCC Reputation of an IP address is the percentage of
its messages known to have been sent to at least 10 recipients. The
defaults are equivalent to <I>rep,never</I> and <I>rep-total,never,20</I>.
Bulk DCC Reputations do not reject mail unless enabled by an
<I>option</I> <I>DCC-rep-on</I> line in a <I>whiteclnt</I> 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 <I>ALL,NEVER</I>, so that nothing is discarded, rejected, or
logged. A common choice is <I>CMN,25,50</I> to reject or discard mail with
common bodies except as overridden by the whitelist of the DCC
server, the sendmail <I>${dcc</I><B>_</B><I>isspam}</I> and <I>${dcc</I><B>_</B><I>notspam}</I> macros, and
<B>-g</B>, and <B>-w</B>.
<A NAME="OPTION-g"><B>-g</B></A> [<I>not-</I>]<I>type</I>
indicates that whitelisted, <I>OK</I> or <I>OK2</I>, counts from the DCC server
for a type of checksum are to be believed. They should be ignored
if prefixed with <I>not-</I>. <I>Type</I> is one of the same set of strings as
for <B>-c</B>. Only <I>IP</I>, <I>env</I><B>_</B><I>From</I>, and <I>From</I> are likely choices. By default
all three are honored, and hence the need for <I>not-</I>.
<A NAME="OPTION-S"><B>-S</B></A> <I>hdr</I>
adds to the list of substitute or locally chosen headers that are
checked with the <B>-w</B> <I>whiteclnt</I> file and sent to the DCC server. The
checksum of the last header of type <I>hdr</I> 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.
<A NAME="OPTION-i"><B>-i</B></A> <I>infile</I>
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 <B>dccproc</B> was started.
<A NAME="OPTION-o"><B>-o</B></A> <I>outfile</I>
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 <B>dccproc</B> was started.
<A NAME="OPTION-l"><B>-l</B></A> <I>logdir</I>
specifies a directory for copies of messages whose checksum target
counts exceed <B>-c</B> thresholds. The format of each file is affected by
<B>-E</B>.
See the FILES section below concerning the contents of the files.
See also the <I>option</I> <I>log-subdirectory-{day,hour,minute}</I> lines in
<I>whiteclnt</I> files described in <B><A HREF="dcc.html">dcc(8)</A></B>.
The directory is relative to the DCC home directory if it is not
absolute
<A NAME="OPTION-B"><B>-B</B></A> <I>dnsbl-option</I>
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 <B><A HREF="dccm.html">dccm(8)</A></B> or <B><A HREF="dccifd.html">dccifd(8)</A></B> but can be useful in situa-
tions where greylisting cannot be used.
<I>Dnsbl-option</I> is either one of the <B>-B</B> <I>set:option</I> forms or
<B>-B</B> <I>domain</I>[any[<I>,bltype</I>]]
<B>-B</B> <I>domain</I>[<I>,IPaddr</I>[<I>/xx</I>[<I>,bltype</I>]]]
<B>-B</B> <I>domain</I>[<I>,IPaddr</I>[<I>-IPaddrHI</I>[<I>,bltype</I>]]]
<I>Domain</I> is a DNS blacklist domain such as <I>example.com</I> that will be
searched. The string <I>any</I>, <I>IPaddr</I>, <I>IPaddr/xxx</I>, or <I>IPaddrLO-IPaddrHI</I>,
specifies which IP addresses found in the DNS blacklist say that
mail messages should be rejected "127.0.0.2" is assumed if no
address(es) are specified. IPv6 addresses can be specified with the
usual colon (:) notation. Host names can be used instead of numeric
addresses. The type of DNS blacklist is specified by <I>bltype</I> as
<I>name</I>, <I>all-names</I>, <I>IPv4</I>, or <I>IPv6</I>. Given an envelope sender domain
name or a domain name in a URL of spam.domain.org and a blacklist of
type <I>name</I>, spam.domain.org.example.com will be looked up. The names
spam.domain.org.example.com, domain.org.example.com, and org.exam-
ple.com will be looked up in blacklists of type <I>all-names</I>. Use
<I>names</I> with DNS blacklists that use wild cards for speed but
<I>all-names</I> for other DNS name blacklists. Blacklist types of <I>IPv4</I>
and <I>IPv6</I> require that the domain name in a URL sender address be
resolved into an IPv4 or IPv6 address. The resolved address from
the mail message is then written as a reversed string of decimal
octets to check the DNS blacklist, as in <I>2.0.0.127.example.com</I>.
More than one blacklist can be specified and blacklists can be
grouped with <B>-B</B> <I>set:group=X</I>. All searching within a group of black-
lists is stopped at the first positive result.
Unlike <B><A HREF="dccm.html">dccm(8)</A></B> and <B><A HREF="dccifd.html">dccifd(8)</A></B>, no <I>option</I> <I>DNSBL-on</I> line is required in
the <I>whiteclnt</I> file. A <B>-B</B> argument is sufficient to show that DNSBL
filtering is wanted by the <B>dccproc</B> user.
<B>-B</B> <I>set:no-client</I>
implies that SMTP client IP addresses and reverse DNS domain
names should not be checked in the following blacklists.
<B>-B</B> <I>set:client</I> restores the default for the following black-
lists.
<B>-B</B> <I>set:no-mail</I><B>_</B><I>host</I>
implies that SMTP envelope Mail_From sender domain names should
not be checked in the following blacklists. <B>-B</B> <I>set:mail</I><B>_</B><I>host</I>
restores the default.
<B>-B</B> <I>set:no-URL</I>
says that URLs in the message body should not be checked in the
in the following blacklists. <B>-B</B> <I>set:URL</I> restores the default.
<B>-B</B> <I>set:no-MX</I>
says MX servers of sender Mail_From domain names and host names
in URLs should not be checked in the following blacklists.
<B>-B</B> <I>set:MX</I> restores the default.
<B>-B</B> <I>set:no-NS</I>
says DNS servers of sender Mail_From domain names and host
names in URLs should not be checked in the following black-
lists. <B>-B</B> <I>set:NS</I> restores the default.
<B>-B</B> <I>set:defaults</I>
is equivalent to all of <B>-B</B> <I>set:client</I>
<B>-B</B> <I>set:mail</I><B>_</B><I>host</I> <B>-B</B> <I>set:URL</I> <B>-B</B> <I>set:MX</I> and <B>-B</B> <I>set:NS</I>
<B>-B</B> <I>set:group=X</I>
adds following DNS blacklists specified with
<B>-B</B> <I>domain</I>[<I>,IPaddr</I>[<I>/xx</I>[<I>,bltype</I>]]]
to group 1, 2, or 3.
<B>-B</B> <I>set:debug=X</I>
sets the DNS blacklist logging level
<B>-B</B> <I>set:msg-secs=S</I>
limits <B>dccproc</B> to <I>S</I> seconds total for checking all DNS black-
lists. The default is 25.
<B>-B</B> <I>set:URL-secs=S</I>
limits <B>dccproc</B> to at most <I>S</I> seconds resolving and checking any
single URL. The default is 11. Some spam contains dozens of
URLs and some "spamvertised" URLs contain host names that need
minutes to resolve. Busy mail systems cannot afford to spend
minutes checking each incoming mail message.
<A NAME="OPTION-L"><B>-L</B></A> <I>ltype,facility.level</I>
specifies how messages should be logged. <I>Ltype</I> must be <I>error</I>, <I>info</I>,
or <I>off</I> to indicate which of the two types of messages are being con-
trolled or to turn off all <B>syslog(3)</B> messages from <B>dccproc</B>. <I>Level</I>
must be a <B>syslog(3)</B> level among <I>EMERG</I>, <I>ALERT</I>, <I>CRIT</I>, <I>ERR</I>, <I>WARNING</I>,
<I>NOTICE</I>, <I>INFO</I>, and <I>DEBUG</I>. <I>Facility</I> must be among <I>AUTH</I>, <I>AUTHPRIV</I>,
<I>CRON</I>, <I>DAEMON</I>, <I>FTP</I>, <I>KERN</I>, <I>LPR</I>, <I>MAIL</I>, <I>NEWS</I>, <I>USER</I>, <I>UUCP</I>, and <I>LOCAL0</I>
through <I>LOCAL7</I>. The default is equivalent to
<B>-L</B> <I>info,MAIL.NOTICE</I> <B>-L</B> <I>error,MAIL.ERR</I>
<B>dccproc</B> exits with 0 on success and with the <B>-x</B> value if the <B>-c</B> thresh-
olds are reached or the <B>-w</B> <I>whiteclnt</I> file blacklists the message. If at
all possible, the input mail message is output to standard output or the
<A NAME="OPTION-o"><B>-o</B></A> <I>outfile</I> 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 <B>dccproc</B> is run more than 500 times in fewer than 5000 seconds, <B>dccproc</B>
tries to start <B><A HREF="dccifd.html">Dccifd(8)</A></B>. The attempt is made at most once per hour.
Dccifd is significantly more efficient than <B>dccproc</B>. With luck, mecha-
nisms such as SpamAssassin will notice when dccifd is running and switch
to dccifd.
</PRE>
<H2><A NAME="FILES">FILES</A></H2><PRE>
<A NAME="FILE-/var/lib/dcc">/var/lib/dcc</A> DCC home directory in which other files are found.
<A NAME="FILE-map">map</A> memory mapped file in the DCC home directory of information
concerning DCC servers.
<A NAME="FILE-whiteclnt">whiteclnt</A> contains the client whitelist in the format described in
<B><A HREF="dcc.html">dcc(8)</A></B>.
<A NAME="FILE-whiteclnt.dccw">whiteclnt.dccw</A>
is a memory mapped hash table corresponding to the <I>whiteclnt</I>
file.
<A NAME="FILE-tmpdir">tmpdir</A> contains temporary files created and deleted as <B>dccproc</B> pro-
cesses the message.
<A NAME="FILE-logdir">logdir</A> is an optional directory specified with <B>-l</B> and containing
marked mail. Each file in the directory contains one message,
at least one of whose checksums reached one of its <B>-c</B> thresh-
olds. The entire body of the SMTP message including its
header is followed by the checksums for the message.
</PRE>
<H2><A NAME="EXAMPLES">EXAMPLES</A></H2><PRE>
The following <B>procmailrc(5)</B> rule adds an X-DCC header to passing mail
:0 f
| /usr/bin/dccproc -ERw whiteclnt
This <B>procmailrc(5)</B> recipe rejects mail with total counts of 10 or larger
for the commonly used checksums:
:0 fW
| /usr/bin/dccproc -ERw whiteclnt -ccmn,10
:0 e
{
EXITCODE=67
:0
/dev/null
}
</PRE>
<H2><A NAME="SEE-ALSO">SEE ALSO</A></H2><PRE>
<B><A HREF="cdcc.html">cdcc(8)</A></B>, <B><A HREF="dcc.html">dcc(8)</A></B>, <B><A HREF="dbclean.html">dbclean(8)</A></B>, <B><A HREF="dccd.html">dccd(8)</A></B>, <B><A HREF="dblist.html">dblist(8)</A></B>, <B><A HREF="dccifd.html">dccifd(8)</A></B>, <B><A HREF="dccm.html">dccm(8)</A></B>,
<B><A HREF="dccsight.html">dccsight(8)</A></B>, <B>mail(1)</B>, <B>procmail(1)</B>.
</PRE>
<H2><A NAME="HISTORY">HISTORY</A></H2><PRE>
Distributed Checksum Clearinghouses are based on an idea of Paul Vixie.
Implementation of <B>dccproc</B> was started at Rhyolite Software in 2000. This
document describes version 1.3.113.
</PRE>
<H2><A NAME="BUGS">BUGS</A></H2><PRE>
<B>dccproc</B> uses <B>-c</B> where <B><A HREF="dccm.html">dccm(8)</A></B> uses <B>-t</B>.
July 20, 2009
</PRE>
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