cdcc(8)            DCC -- Distributed Checksum Clearinghouse           cdcc(8)


NAME

     cdcc - Control Distributed Checksum Clearinghouse


SYNOPSIS

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


DESCRIPTION

     Cdcc is used to clear, control, and query the control file used by Dis-
     tributed 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 con-
     tained 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 op-
     eration that requires a password without specifying a server-ID or with-
     out 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"
     or

           % cdcc "host localhost;info" stats

   OPTIONS
     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 com-
          plaints about the map file, and some messages about successful com-
          mands.

     -h homedir
          overrides the default DCC home directory, which is often /var/lib/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 op-
          erations 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.

   OPERATIONS
     Local operations include the following:

     help [command]
           lists information about one or all available commands and opera-
           tions.

     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 millisec-
           onds between -4000 and +4000 following the string RTT. The adjust-
           ment 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 as-
           sumed if greylist mode has been set with the grey on command, See
           dccd(8).

           If both the client-ID and the password are absent, the anonymous
           client-ID, 1, is used.  The string anon is equivalent to the anony-
           mous 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 con-
           sists of blank lines and comment lines starting with '#' other
           lines in the same format as the arguments to the add and load oper-
           ations.  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
           chosen.

     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 set-
           ting 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 re-
           solved 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
           server.

           The currently preferred IP address is indicated by an asterisk.
           The "brand" of the server, its DCC ID, and its IP address are dis-
           played 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 im-
           posed 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 list-
           ed server IP addresses.

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

           -N displays the reverse DNS name of each server.

     debug [on | off]
           enables or disables debugging information from the DCC client li-
           brary.

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

           IPv6.

     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 appropriate-
           ly, 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.

   DCC SERVER COMMANDS
     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 com-
     mand.  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.

     stop
          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
          peers.

     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 num-
          ber 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 connec-
          tions 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
          complete.

     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 de-
                   tect 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 speci-
     fied on the command line.


FILES




     /var/lib/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.


SEE ALSO

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


HISTORY

     Implementation of cdcc was started at Rhyolite Software in 2000.  This
     describes version 1.2.16.

                               November 19, 2003                             6

Man(1) output converted with man2html modified for the DCC $Date 2001/04/29 03:22:18 $