Provided by: dcc-common_1.2.74-2_i386 bug


     cdcc - Control Distributed Checksum Clearinghouse


     cdcc [-Vdq] [-h homedir] [-c ids] [op1 op2 ... [-]]


     Cdcc is used to clear, control, and query the control file used by
     Distributed Checksum Clearinghouse clients such as dccm(8).  The host
     names, UDP port numbers, IDs, and passwords local clients use to talk to
     servers as well as IP addresses, round trip times, and other information
     are contained in the map file.  While cdcc is set-UID, it uses the real
     UID only when accessing the map file.  It refuses to display sensitive
     information such as passwords unless the real UID is the same as the
     effective UID.  Note that cdcc needs to be set to a UID that can read and
     write the map file, but that UID need not be 0.

     Cdcc is also used to send commands to DCC servers to tell them to stop,
     reload their lists of DCC IDs, turn on tracing, and so forth.

     Many commands sent to DCC servers require a numeric DCC ID and a password
     recognized by the server.  A DCC password is a 1-32 character string that
     does not contain blank, tab, newline or carriage return characters.  The
     ID is specified with the id operation.  If cdcc is run with a real UID
     that can read the ids file and a password is not specified (see the
     password operation), then the current password for the specified ID in
     the ids file will be used.  If no ids file is available and a password
     and DCC ID are not specified, cdcc uses the anonymous DCC client-ID.  DCC
     servers do not expect a password from clients using the anonymous client-
     ID, but they also won’t honor control requests.

     Operations that modify the map file can only be performed when the real
     UID is sufficient to modify the file directly.  Trying to perform an
     operation that requires a password without specifying a server-ID or
     without using a UID that can access the ids file produces an error
     message complaining about a "privileged operation."

     Commands and operations are read from the command line or from stdin.  A
     series of op1 op2 ... operations followed a - (a dash) causes operations
     to be read from stdin after the command line operations are processed.
     Semi-colons or newlines separate commands in UNIX command-line "words,"
     as well as when commands are read from stdin.  Since each command line
     operation must be a shell "word," quotes are often required as in

           % cdcc "load map.txt"

           % cdcc "host localhost;info" stats

     The following options are available:

     -V   displays the version of the DCC controller.

     -d   enables debugging output from the DCC client library.  Additional -d
          options increase the number of messages.  -q quiets initial
          complaints about the map file, and some messages about successful

     -h homedir
          overrides the default DCC home directory, which is often /var/dcc.
          See the homedir operation.

     -c ids
          specifies file containing DCC IDs and passwords known by the local
          DCC server.  An ids file that can be read by others cannot be used.
          The format of the ids file is described in dccd(8).

     op1 op2 ...
          are operations or commands such as "id 100; stop".  Commands or
          operations specified on the command line are performed before the
          first interactive request.  The last command can be - to specify
          that additional commands should be read from stdin.

     Local operations include the following:

     help [command]
           lists information about one or all available commands and

     exit  stops cdcc

     grey [on | off]
           switches between DCC and greylist servers.

     homedir [path]
           displays or specifies the DCC home directory.

     file [map]
           displays or specifies the name or path of the map file.  The string
           "-" specifies the default file map in the DCC home directory.

     new map [map]
           creates a new, empty file for DCC server host names, port numbers,
           passwords, and so forth.  There must not already be a file of the
           same name.  The default is map in the DCC home directory.

     delete host[,port]
           deletes the entry in the map file for host and UDP port. If
           greylist mode has been set with the grey on command, the entry for
           the grelist server at host is deleted.

     add host[,port] [RTT+adj|RTT-adj] [Greylist] [client-ID [password]]
           adds an entry to the map file.  The port can be "-" to specify the
           default DCC server port number.

           An adjustment to the round trip time is a multiple of 10
           milliseconds between -4000 and +4000 following the string RTT.  The
           adjustment is added to the average measured round trip time when
           the DCC client software picks the "nearest" DCC server, or the
           server with the smallest RTT.  If an IP address is mentioned more
           than once in the list of servers, for example because it is among
           the addresses for more than one server name, conflicts among RTT
           adjustments are resolved by picking the adjustment with the largest
           absolute value.

           Greylist marks an entry for a greylist servers.  Greylist is
           assumed if greylist mode has been set with the grey on command, See

           If both the client-ID and the password are absent, the anonymous
           client-ID, 1, is used.  The string anon is equivalent to the
           anonymous client-ID.  A null password string is assumed if the
           password is missing and the client-ID is 1 or also missing.

     load info-file
           loads the current parameter file with the host names, port numbers,
           IDs, and passwords in info-file.  Standard input is understood if
           info-file is "-".

           A suitable file can be created with the info operation.  It
           consists of blank lines and comment lines starting with ’#’ other
           lines in the same format as the arguments to the add and load
           operations.  Note that output of the info command will lack
           passwords unless it is run by a privileged user.

     host [hostname]
           specifies the host name of the DCC server to which commands should
           be sent.  If hostname is "-", the current default DCC server is

     port [port]
           specifies the UDP port number of the DCC server to which commands
           should be sent.  The default is 6277 or 6276 depending on the
           setting of the greylist mode controlled with the grey command.

     password secret
           specifies the password with which to sign commands sent to the DCC
           server specified with the server and port operations.

     id [ID]
           specifies or displays the numeric DCC ID for commands sent to the
           DCC server specified with the server and port operations.  If no
           password is specified with the password command, the password is
           sought in the local ids.

     info [-N]
           displays information about the connections to DCC servers.  It
           starts with the current date and name of the current map file or
           says that cdcc is using the implicit file created with the server
           and port operations.  It then says when host names will next be
           resolved into IP addresses, the smallest round trip time to the IP
           addresses of known DCC servers.  The host name, UDP port number (or
           dash if it is the default), DCC client-ID, and password (if cdcc is
           used by a privileged user) are shown in one line per configured DCC

           The currently preferred IP address is indicated by an asterisk.
           The "brand" of the server, its DCC ID, and its IP address are
           displayed in one line per IP address.  The performance of the
           server at each IP address in the most recent 32 operations is
           displayed in a second line.  The second line ends with the measured
           delay imposed by the server on requests with this client’s ID.

           -N displays the reverse DNS name of each server.

     RTT [-N]
           measures the round trip time to the DCC servers.  It does this by
           discarding accumulated information and forcing a probe of all
           listed server IP addresses.

           Beware that when run with sufficient privilege, the RTT operation
           is like the info and load operations and displays cleartext

           -N displays the reverse DNS name of each server.

     debug [on | off | TTL=x]
           increases or decreases debugging information from the DCC client
           library or sets the IP TTL on queries to the server.  See -d.

           Some systems do not include the functions required to change the IP
           TTL.  Others apparently including Microsoft Windows XP include
           required functions but have no apparent effect.

     IPv6 [on | off]
           sets a switch to cause clients using the map file to try to use

     SOCKS [on off]
           sets a switch to cause DCC clients using the map to use the SOCKS5
           protocol, if they have been built with a SOCKS library.  The socks
           library linked with the DCC client must be configured
           appropriately, often including knowing which DCC servers must be
           connected via the SOCKS proxy and which can be reached directly.
           DCC clients use SOCKS functions such as Rsendto() with all or no
           servers depending on the setting of this switch.

     Commands that can be sent to a DCC server include the following.  Most of
     the commands must be used with the server’s ID specified with the id
     command.  The specified ID is included in the commands sent to the server
     The command itself is digitally signed with the first password associated
     with the ID in the ids file.  The server requires that the signature
     match one of the passwords associated with the ID in its ids file.

     delck type hex1 hex2 hex3 hex4
          asks the server to delete the type checksum with value hex1 hex2
          hex3 hex4.  The type and checksum values can be found in dccproc(8)
          and dccm(8) log files or computed with dccproc-QC.

          There are very few situations where it makes sense to bother to
          delete checksums.  For example, mail that was accidentally reported
          with a target count of "MANY" is either private and so will not be
          seen by other people and so will not be affected, or it is bulk and
          its source so must have already been white-listed by recipients.

     stats [all | clear]
          displays current status and statistics from the current DCC server
          or for all known DCC servers.

     clients [-n] [-s] [-i] [-a] [max [thold]]
          displays some of the clients recently seen by the server.
          clients -n displays only the IP addresses and not the names of
          clients.  clients -s sorts the clients by the number of requests
          they have made.  clients -i counts clients with the same client-ID
          as single entities.  clients -a produces 24 hour average values.
          clients max displays only the most recent max clients.  clients max
          thold displays the most recent max clients that have made at least
          thold requests.

          The mechanism that implements this command involves asking the DCC
          server for the first approximately 100 clients, then the second
          about 100, and so on, If entries change position in the complete
          list maintained by the server between requests, the displayed list
          will have duplicate or missing entries.

          Only clients heard from since the server was started or stats clear
          was last used are displayed.

          tells the DCC server to exit.

     reload IDs
          tells the DCC server to reload its DCC ids file.  This is handy to
          cause the server to notice changes in the file.

     flood check
          tells the DCC server to check for changes in the flod file and try
          to restart any of the streams to peers that are broken.

     flood shutdown
          tells the DCC server to cleanly stop flooding checksums to and from
          peers.  The server will wait for sending and receiving peers to
          agree to stop.  Each flood shutdown or flood halt request increases
          a count of reasons why the server should not flood checksums.

     flood halt
          tells the DCC server to abruptly stop flooding checksums to and from

     flood rewind server-ID
          tells the DCC server to ask its peer with server-ID to rewind and
          resend its stream of checksums.

     flood ffwd in server-ID
          tells the DCC server to ask its peer to "fast forward" or skip to
          the end of the incoming flood.

     flood ffwd out server-ID
          tells the DCC server to "fast forward" or skip to the current end of
          the flood to its peer.

     flood resume
          tells the DCC server to reduce the number of reasons to not flood
          checksums increased by flood shutdown and flood halt. When the
          number of reasons reaches zero, the server tries to resume flooding.

     flood list
          displays the list of current incoming and outgoing floods.  Each
          line contains the server-ID of the peer, the IP address and port
          used for the outgoing flood, the address for the incoming flood if
          different, and the host name.  Only the server-IDs of flooding peers
          are disclosed with the server’s ID.

     flood stats [clear] { server-ID | all }
          displays counts of checksum reports sent and received by the current
          flooding connections to and from server-ID or all flooding
          connections and then optionally clears the counts.

     DB unlock
          is used by dbclean to tell the server that the database expiration
          has begun.

     DB new
          is used by dbclean to tell the server that the database cleaning is

     trace mode {on|off}
          turns the server’s tracing mode on or off.  Mode must be one of:
            ALL    all tracing
            ADMN   administrative requests from cdcc
            ANON   errors by anonymous clients
            CLNT   errors by authenticated clients
            RLIM   rate-limited messages
            QUERY  all queries and reports
            RIDC   messages concerning the report-ID cache that is used to
                   detect duplicate reports from clients
            FLOOD  messages about inter-server flooding
            IDS    unknown server-IDs in flooded reports
            BL     blacklisted clients

     cdcc exits 0 on success, and >0 if an error occurs in operations
     specified on the command line.


     /var/dcc  DCC home directory
     map       memory mapped file in the home DCC home directory of server
               host names, port numbers, passwords, measured round trip times
               (RTT), and so forth.
     ids       list of IDs and passwords, as described in dccd(8).  It is only
               required by systems running the DCC server, but is used by cdcc
               if available.


     dbclean(8), dcc(8), dccd(8), dblist(8), dccifd(8), dccm(8), dccproc(8),


     Implementation of cdcc was started at Rhyolite Software in 2000.  This
     describes version 1.2.74.