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| author | Peter Gervai <grin@grin.hu> |
|---|---|
| date | Tue, 10 Mar 2009 14:31:24 +0100 |
| parents | c7f6b056b673 |
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> <HTML> <HEAD> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1"> <TITLE>dccifd.0.8</TITLE> <META http-equiv="Content-Style-Type" content="text/css"> <STYLE type="text/css"> BODY {background-color:white; color:black} ADDRESS {font-size:smaller} IMG.logo {width:6em; vertical-align:middle} </STYLE> </HEAD> <BODY> <PRE> <!-- Manpage converted by man2html 3.0.1 --> <B><A HREF="dccifd.html">dccifd(8)</A></B> Distributed Checksum Clearinghouse <B><A HREF="dccifd.html">dccifd(8)</A></B> </PRE> <H2><A NAME="NAME">NAME</A></H2><PRE> <B>dccifd</B> -- Distributed Checksum Clearinghouse Interface Daemon </PRE> <H2><A NAME="SYNOPSIS">SYNOPSIS</A></H2><PRE> <B>dccifd</B> [<B>-VdbxANQ</B>] [<B>-G</B> <I>on</I> | <I>off</I> | <I>noIP</I> | <I>IPmask/xx</I>] [<B>-h</B> <I>homedir</I>] [<B>-I</B> <I>user</I>] [<B>-p</B> <I>/sock</I> | <I>host,port,rhost/bits</I>] [<B>-o</B> <I>/sock</I> | <I>host,port</I>] [<B>-D</B> <I>local-domain</I>] [<B>-m</B> <I>map</I>] [<B>-w</B> <I>whiteclnt</I>] [<B>-U</B> <I>userdirs</I>] [<B>-a</B> <I>IGNORE</I> | <I>REJECT</I> | <I>DISCARD</I>] [<B>-t</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>-l</B> <I>logdir</I>] [<B>-R</B> <I>rundir</I>] [<B>-r</B> <I>rejection-msg</I>] [<B>-T</B> <I>tmpdir</I>] [<B>-j</B> <I>maxjobs</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>dccifd</B> 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 <B>dccifd</B> which in turn reports related checksums to the near- est DCC server and adds an <I>X-DCC</I> SMTP header line to the message. The MTA is told to reject the message if it is unsolicited bulk. <B>Dccifd</B> is similar to the DCC sendmail milter interface, <B><A HREF="dccm.html">dccm(8)</A></B> and the DCC Procmail interface, <B><A HREF="dccproc.html">dccproc(8)</A></B>. <B>Dccifd</B> is more efficient than <B><A HREF="dccproc.html">dccproc(8)</A></B> but not restricted to use with sendmail like <B><A HREF="dccm.html">dccm(8)</A></B>. 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 use a simple ASCII protocol a subset of SMTP to send a mail message including its SMTP envelope to the daemon. <B>Dccifd</B> responds with an indication of whether the message is unsolicited bulk and an optional copy of the message with an <I>X-DCC</I> header added. The ASCII protocol is described below and in the <I>include/dccif.h</I> file in the DCC source. There is a sample C interface routine in the <I>dcclib/dccif.c</I> file in the DCC source and the <I>dcclib.a</I> library generated from the source. A <I>Perl</I> ver- sion of the interface routine is in <I>dccifd/dccif.pl</I>. Test or demonstra- tion programs in the style of <B><A HREF="dccproc.html">dccproc(8)</A></B> that use those interface rou- tines are in <I>dccifd/dccif-test</I>. A subset of ESMTP can be used instead of the ASCII protocol to connect <B>dccifd</B> to postfix as a "Before-Queue Content Filter." See the <B>-o</B> flag. Since the checksums of messages that are whitelisted locally by the <B>-w</B> <I>whiteclnt</I> file are not reported to the DCC server, <B>dccifd</B> knows nothing about the total recipient counts for their checksums and so cannot add <I>X-DCC</I> header lines to such messages. Enable the daemon and put its parameters in the <I>dcc</I><B>_</B><I>conf</I> file and start the daemon with the <I>start-dccifd</I> script. The list of servers that <B>dccifd</B> contacts is in the memory mapped file <I>map</I> shared by local DCC clients. The file is maintained with <B><A HREF="cdcc.html">cdcc(8)</A></B>. <A NAME="OPTIONS"><B>OPTIONS</B></A> The following options are available: <A NAME="OPTION-V"><B>-V</B></A> displays the version of <B>dccifd</B>. <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. A single <B>-d</B> aborted SMTP transactions including those from some "dictionary attacks." <A NAME="OPTION-b"><B>-b</B></A> causes the daemon to not detach itself from the controlling tty and put itself into the background. <A NAME="OPTION-x"><B>-x</B></A> 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, <B>dccifd</B> 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 <B>-x</B>, 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. <A NAME="OPTION-A"><B>-A</B></A> adds to existing X-DCC headers in the message instead of replacing existing headers of the brand of the current server. <A NAME="OPTION-N"><B>-N</B></A> neither adds, deletes, nor replaces existing X-DCC headers in the message. Each message is logged, rejected, and otherwise handled the same. <A NAME="OPTION-Q"><B>-Q</B></A> only queries the DCC server about the checksums of messages instead of reporting and querying. This is useful when <B>dccifd</B> is used to filter 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 <I>MXDCC</I> lines in the global <I>whiteclnt</I> file for your MX mail servers that use DCC than <B>-Q</B>. <A NAME="OPTION-G"><B>-G</B></A> <I>on</I> | <I>off</I> | <I>noIP</I> | <I>IPmask/xx</I> controls <I>greylisting</I>. At least one working greylist server must be listed in the <I>map</I> file in the DCC home directory. If more than one is named, they must "flood" or change checksums and they must use the same <B>-G</B> parameters. See <B><A HREF="dccd.html">dccd(8)</A></B>. Usually all dccm or dccifd DCC client processes use the same <B>-G</B> parameters. <I>IPmask/xx</I> and <I>noIP</I> remove part or all of the IP address from the greylist triple. The CIDR block size, <I>xx</I>, 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>IPmask/96</I> differs from <I>noIP</I> for IPv4 addresses, because the former retains the IPv4 to IPv6 mapping prefix. <A NAME="OPTION-h"><B>-h</B></A> <I>homedir</I> overrides the default DCC home directory, <I>@prefix@</I>. <A NAME="OPTION-I"><B>-I</B></A> <I>user</I> specifies the UID and GID of the process. <A NAME="OPTION-p"><B>-p</B></A> <I>/sock/name</I> | <I>host,port,rhost/bits</I> overrides the default address at which programs contact <B>dccifd</B>. The default is a UNIX domain socket named dccifd in the DCC home direc- tory. 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 <B>dccifd</B>. 127.0.0.1 or <I>localhost</I> are common choices for <I>host</I>. The string <I>@</I> specifies IN_ADDRANY or all local IP addresses. 127.0.0.0/8 is a common choice for <I>rhost/bits</I>. <A NAME="OPTION-o"><B>-o</B></A> <I>/sock</I> | <I>host,port</I> enables SMTP proxy mode instead of the ASCII protocol and specifies the output connection when <B>dccifd</B> acts as an SMTP proxy. It is the address of the SMTP server for which <B>dccifd</B> acts as SMTP client. When <I>/sock</I> is <I>/dev/null</I>, <B>dccifd</B> acts as if there were downstream SMTP server that always answers "250 ok". The string <I>@</I> specifies the same IP address as the incoming TCP connection. The input to <B>dccifd</B> in SMTP proxy mode is specified with <B>--p</B>. For example, <B>-p</B> <I>127.0.0.1,10025,127.0.0.1/32</I> <B>-o</B> <I>127.0.0.1,10026</I> could be used to connect <B>dccifd</B> with Postfix as described in the documenta- tion in version 2.2.1 Postfix documentation. See below concerning the subset of ESMTP used in this mode. <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> file in the DCC home directory. It should be created with 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 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 <I>X-DCC</I> header, and whose checksums should not be reported to the DCC server. If the pathname <I>whiteclnt</I> is not absolute, it is relative to the DCC home directory. The format of the <B>dccifd</B> whiteclnt file is the same as the <I>whitelist</I> files used by <B><A HREF="dbclean.html">dbclean(8)</A></B> and the <I>whiteclnt</I> file used by <B><A HREF="dccproc.html">dccproc(8)</A></B>. See <B><A HREF="dcc.html">dcc(8)</A></B> for a description of DCC white and blacklists. Because the contents of the <I>whiteclnt</I> file are used frequently, a companion file is automatically created and maintained. It has the same path- name but with an added suffix of <I>.dccw</I> 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 <I>X-DCC</I> header line by <B>dccifd</B> A whitelist entry for a checksum also prevents rejecting or discarding the message based on DCC recipient counts as specified by <B>-a</B> and <B>-t</B>. 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 <I>env</I><B>_</B><I>To</I> <I>whiteclnt</I> entry of "OK" for the checksum of its recipient address acts like any other <I>whiteclnt</I> 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 <I>whiteclnt</I> file, <B>dccifd</B> 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. <A NAME="OPTION-U"><B>-U</B></A> <I>userdirs</I> enables per-user <I>whiteclnt</I> files and log directories. Each target of a message can have a directory of log files named <I>userdirs/addr/log</I> where <I>addr</I> is the local user or mailbox name com- puted by the MTA. The name of each user's log directory must be <I>log</I>. If it is not absolute, <I>userdirs</I> is relative to the DCC home directory. The directory containing the log files must be named <I>log</I> and it must be writable by the <B>dccifd</B> 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 <B>dccifd</B> process, but they have <I>group</I> and <I>other</I> read and write permis- sions copied from the corresponding <I>log</I> directory. To ensure the privacy of mail, it may be good to make the directories readable only by <I>owner</I> and <I>group</I>, and to use a cron script that changes the owner of each file to match the grandparent <I>addr</I> directory. There can also be a per -user whitelist file named <I>userdirs/addr/whiteclnt</I> for each address <I>addr.</I> Any checksum that is not white- or blacklisted by an individual addressee's <I>whiteclnt</I> file is checked in the main <B>-w -whiteclnt</B> file. A missing per- addressee <I>whiteclnt</I> 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 <I>whiteclnt</I> files and the <I>addr</I> directories containing them must be writable by the <B>dccifd</B> process. <I>Option</I> lines in per-user whiteclnt files can be used to modify many aspects of <B>dccifd</B> filtering, as described in the main dcc man page. For example, an <I>option</I> <I>dcc-off</I> line turns off DCC filtering for individual mailboxes. <A NAME="OPTION-a"><B>-a</B></A> <I>IGNORE</I> | <I>REJECT</I> | <I>DISCARD</I> specifies the action taken when <B>dccifd</B> is in proxy mode with <B>-o</B> and DCC server counts or <B>-t</B> thresholds say that a message is unsolicited and bulk. <I>IGNORE</I> causes the message to be unaffected except for adding the <I>X-DCC</I> header line to the message. This turns off DCC filtering. Spam can also be <I>REJECT</I>ed or (when in proxy mode with <B>-o</B>) accepted and silently <I>DISCARD</I>ed without being delivered to local mailboxes. The default is <I>REJECT</I>. Mail forwarded via IP addresses marked <I>MX</I> or <I>MXDCC</I> in the main <I>whiteclnt</I> file is treated as if <B>-a</B> <I>DISCARD</I> were specified. This prevents "bouncing" spam. The effects of the <B>-w</B> <I>whiteclnt</I> are not affected by <B>-a</B>. <A NAME="OPTION-t"><B>-t</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 the DCC are controlled by thresholds on checksum types <I>rep</I> and <I>rep-total</I>. Mes- sages from an IP address that the DCC database says has sent more than <B>-t</B> <I>rep-total,log-thold</I> messages are logged. A DCC Reputation is computed for messages received from IP addresses that have sent more than <B>-t</B> <I>rep-total,log-thold</I> 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 <B>-t</B> <I>rep,never</I> and <B>-t</B> <I>rep-total,never,20</I>. Bad 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>-t</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. <I>Hdr</I> can be <I>HELO</I> to specify the SMTP envelope HELO value. <I>Hdr</I> can also be <I>mail</I><B>_</B><I>host</I> to specify the host name from the Mail_from value in the SMTP envelope. As many as six different sub- stitute headers can be specified, but only the checksum of the first of the six will be sent to the DCC server. <A NAME="OPTION-l"><B>-l</B></A> <I>logdir</I> specifies a directory in which files containing copies of messages processed by <B>dccifd</B> are kept. They can be copied to per-user direc- tories specified with <B>-U</B>. 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 <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-R"><B>-R</B></A> <I>rundir</I> specifies the "run" directory where the file containing the daemon's process ID is stored. The default value is <I>@dcc_rundir@</I>. <A NAME="OPTION-T"><B>-T</B></A> <I>tmpdir</I> changes the default directory for temporary files from the default. The default is the directory specified with <B>-l</B> or the system default if <B>-l</B> is not used. The system default is often <I>/tmp</I>. <A NAME="OPTION-D"><B>-D</B></A> <I>local-domain</I> specifies a host or domain name by which the system is known. There can be several <B>-D</B> settings. To find the per-user log directory and whitelist for each mail recipient, <B>dccifd</B> must know each recipient's user name. The ASCII protocol used between and the MTA includes an optional user name with each SMTP recipient address. When the user name is absent when the ASCII protocol is used or when the subset of ESMTP enabled with <B>-o</B> is used, and when the SMTP recipient address includes an <I>at</I> <I>sign</I> (@) each mail address is checked against the list of <I>local-domain</I>s. The part of the recipient address remaining after longest matching <I>local-domain</I> (if any) is taken as the user name. The match is anchored at the right or the end of the recipient address. It must start at a period (.) or <I>at</I> <I>sign</I> (@) in the domain name part of the address. If <I>local-domain</I> starts with an asterisk (*) indicating a wildcard, preceding sub-domain names are discarded to compute the user name. Otherwise, the computed user name will include any unmatched sub- domain names. The default value of <I>local-domain</I> when there are no <B>-D</B> settings is the host name of the system. <A NAME="OPTION-r"><B>-r</B></A> <I>rejection-msg</I> specifies the rejection message in <B>-o</B> proxy mode for unsolicited bulk mail or for mail temporarily blocked by <I>greylisting</I> when <B>-G</B> is specified. The first <B>-r</B> <I>rejection-msg</I> 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 <B>-r</B> <I>rejection-msg</I> 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 <I>rejection-msg</I> is the zero-length string, the <B>-r</B> setting is counted but the corresponding message is not changed. <I>Rejection-msg</I> 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 <B>-B</B> <I>set:rej-msg=rejection-msg</I> to set the status message for mail rejected by DNS blacklists. <A NAME="OPTION-j"><B>-j</B></A> <I>maxjobs</I> 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 <B>dccifd</B> with <B>-d</B> and see the starting message in the system log to see the limit. <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>[<I>,IPaddr</I>[<I>/xx</I>[<I>,bltype</I>]]] <I>Domain</I> is a DNS blacklist domain such as example.com that will be searched. <I>IPaddr</I>[<I>/xxx</I>] 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>IPaddr</I> 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 <I>bltype</I> as <I>name</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 tried. 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 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 <I>option</I> <I>DNSBL-on</I> line appears in the global or per-user <I>whiteclnt</I> file. <B>-B</B> <I>set:no-client</I> says 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> says 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:no-temp-fail</I> <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 later 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>dccifd</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>dccifd</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 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. <B>-B</B> <I>set:rej-msg=rejection-msg</I> sets the SMTP rejection message for the following blacklists. <I>Rejection-msg</I> must be in the same format as for <B>-r</B>. If <I>rejection-msg</I> is null, the default is restored. The default DNS blacklist rejection message is the first message set with <B>-r</B>. <B>-B</B> <I>set:temp-fail</I> causes <B>dccifd</B> 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. <B>-B</B> <I>set:no-temp-fail</I> restores the default of assuming a negative answer for DNS responses that take too long. <B>-B</B> <I>set:maxjobs=X</I> sets maximum number of helper processes to <I>X</I>. In order to use typical single-threaded DNS resolver libraries, <B>dccifd</B> 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 <B>-j</B>. <B>-B</B> <I>set:progpath=@libexecdir@/dns-helper</I> changes the path to the helper program. <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>dccifd</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>dccifd</B> normally sends counts of mail rejected and so forth to 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. <A NAME="Protocol"><B>Protocol</B></A> <B>Dccifd</B> 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 <B>-o</B>. 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 <B>-o</B> depends on a list of local domain names specified with <B>-D</B> to find per-user log direc- tories and whitelist files. If neither XFORWARD nor XCLIENT are used, <B>dccifd</B> 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 <B>dccifd</B>. Each ends with a newline ('\n') character. options zero or more blank-separated strings among: <I>spam</I> the message is already known to be spam <I>body</I> return all of the headers with the added <I>X-DCC</I> header line and the body <I>header</I> return the <I>X-DCC</I> header <I>query</I> ask the DCC server about the message without reporting it, as if <B>dccifd</B> were running with <B>-Q</B>. <I>grey-query</I> only query the greylist server for this mes- sage. <B>-G</B> <I>on</I> must be in use. <I>no-reject</I> suppress the overall, one character line 'R' result. This can be useful when using <B>dccifd</B> only for greylisting. <I>log</I> ensure that this message is logged as if <B>dccifd</B> were running with <B>-t -all,0,</B> 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. The string "0.0.0.0\n" is understood the same as the null string, meaning that both the IP address and host name are absent. If the client IP address is absent, then the IP address and host name are taken from the first non-local Received header if it has the standard "name (name [IP address])..." format. Non-standard Received headers com- monly added by qmail as well as Received headers specifying IP addresses marked <I>MX</I> or <I>MXDCC</I> in the global <B>-w</B> <I>whiteclnt</I> file are skipped. HELO SMTP HELO value or nothing, followed by a newline ('\n') character. If the HELO value is null and the IP address of the SMTP client are not supplied, they will be taken from the same Received: header that supplies the IP address. sender or SMTP <I>Mail</I> <I>From</I> command value for the env_from checksum. If the sender is null, the contents of the first Return- Path: or UNIX style From_ header is used. recipients or SMTP <I>Rcpt</I> <I>To</I> recipient mailboxes followed by correspond- ing local user names, one (mailbox,user) pair to a line. Each optional local user name is separated from the corre- sponding mailbox recipient address by a carriage return ('\r'). A local user name can be null if it is not known, but each recipient mailbox must be non-null. If there are no lines of (mailbox,user) pairs and if the <I>spam</I> option is not included, then the <I>query</I> is assumed. Mailboxes without user names will lack per-user log files and will not invoke a per-user whitelist. 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 <B>shutdown(2)</B>. <B>Dccifd</B> responds with three things. First is a one character line of the overall result advising the MTA: 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 result. Second is a line of characters indicating the disposition of the message for each corresponding recipient: A deliver the message G discard the message during a greylist embargo R discard the message as spam 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 accept- ing the message for all recipients and then discard it for those that would reject it. Finally, if the <I>body</I> or <I>header</I> strings are in the first line of <I>options</I> sent by the MTA to the daemon, then the <I>X-DCC</I> header line or the entire body with the <I>X-DCC</I> header line follows. </PRE> <H2><A NAME="FILES">FILES</A></H2><PRE> <A NAME="FILE-@prefix@">@prefix@</A> is the DCC home directory in which other files are found. <A NAME="FILE-@libexecdir@/start">@libexecdir@/start</A>-dccifd and <A NAME="FILE-@libexecdir@/rcDCC">@libexecdir@/rcDCC</A> are scripts used to start the daemon. <A NAME="FILE-dcc/dcc_conf">dcc/dcc_conf</A> contains parameters used by the scripts to start DCC daemons and cron jobs. <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 mes- sage, at least one of whose checksums reached its <B>-t</B> 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 <I>./configure</I> <I>--with-max-log-size=xx</I> 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 <B>-w</B> <I>whiteclnt</I> file. Each log file ends with the <I>X-DCC</I> header line added to the message and the dis- position of the message. <A NAME="FILE-map">map</A> is the memory mapped file of information concerning DCC servers in the DCC home directory. <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 of the <I>whiteclnt</I> file. <A NAME="FILE-dccifd.pid">dccifd.pid</A> in the <B>-R</B> <I>rundir</I> directory contains daemon's process ID. </PRE> <H2><A NAME="EXAMPLES">EXAMPLES</A></H2><PRE> Dccifd can be used as Postfix Before-Queue Content filter. In some tests these values for <B>-p</B> and <B>-o</B> in <I>dcc</I><B>_</B><I>conf</I>. DCCIFD_ENABLE=on DCCIFD_ARGS="-p 127.0.0.1,10025,127.0.0.1/32 -o 127.0.0.1,10026 worked with these lines in /etc/postfix/master.cf smtp inet n - n - - smtpd -o smtpd_proxy_filter=127.0.0.1:10025 127.0.0.1:10026 inet n - n - - smtpd -o smtpd_authorized_xforward_hosts=127.0.0.0/8 -o smtpd_client_restrictions= -o smtpd_helo_restrictions= -o smtpd_sender_restrictions= -o smtpd_recipient_restrictions=permit_mynetworks,reject -o smtpd_data_restrictions= -o mynetworks=127.0.0.0/8 -o receive_override_options=no_unknown_recipient_checks </PRE> <H2><A NAME="SEE-ALSO">SEE ALSO</A></H2><PRE> <B><A HREF="cdcc.html">cdcc(8)</A></B>, <B><A HREF="dbclean.html">dbclean(8)</A></B>, <B><A HREF="dcc.html">dcc(8)</A></B>, <B><A HREF="dccd.html">dccd(8)</A></B>, <B><A HREF="dblist.html">dblist(8)</A></B>, <B><A HREF="dccm.html">dccm(8)</A></B>, <B><A HREF="dccproc.html">dccproc(8)</A></B>, <B><A HREF="dccsight.html">dccsight(8)</A></B>, </PRE> <H2><A NAME="HISTORY">HISTORY</A></H2><PRE> Implementation of <B>dccifd</B> Distributed Checksum Clearinghouses are based on an idea of Paul Vixie with code designed and written at Rhyolite Software starting in 2000. was started at Rhyolite Software in 2002. This docu- ment describes version 1.3.103. </PRE> <H2><A NAME="BUGS">BUGS</A></H2><PRE> <B>dccifd</B> uses <B>-t</B> where <B><A HREF="dccproc.html">dccproc(8)</A></B> uses <B>-c</B>. By default <B>dccifd</B> look for its UNIX domain socket in the DCC home direc- tory, but <B><A HREF="dccm.html">dccm(8)</A></B> looks in its <B>-R</B> <I>rundir</I>. Systems without <B>setrlimit(2)</B> and <B>getrlimit(2)</B> RLIMIT_NOFILE can have problems with the default limit on the number of simultaneous jobs, the value of <B>-j</B>. Every job requires four open files. These problems are usually seen with errors messages that say something like dccifd[24448]: DCC: accept(): Result too large A fix is to use a smaller value for <B>-j</B> or to allow <B>dccifd</B> to open more files. February 26, 2009 </PRE> <HR> <ADDRESS> Man(1) output converted with <a href="http://www.oac.uci.edu/indiv/ehood/man2html.html">man2html</a> modified for the DCC $Date 2001/04/29 03:22:18 $ <BR> <A HREF="http://www.dcc-servers.net/dcc/"> <IMG SRC="http://logos.dcc-servers.net/border.png" class=logo ALT="DCC logo"> </A> <A HREF="http://validator.w3.org/check?uri=referer"> <IMG class=logo ALT="Valid HTML 4.01 Strict" SRC="http://www.w3.org/Icons/valid-html401"> </A> </ADDRESS> </BODY> </HTML>