Name
        CLX

Authors
        Franta Bendl, DJ0ZY
        Bernhard ("Ben") Buettner, DL6RAI (clx@dl6rai.muc.de)

Description
        A PacketCluster like system running on Linux.

Status
        Version 4.04 Released February 7, 1999.

System Requirements
        Linux Kernel > 2.x with Alan Cox's AX.25
        driver, TCP/IP networking, SysV IPC.
        Needs Perl and AX.25 hardware or TNT/WAMPES.

Detail
        PacketCluster nodes have been available since around
        1986. The original software was written by Dick
        Newell, AK1A, and is running under DOS. CLX is a
        system which clones a PacketCluster node. To the
        outside user, commands and features are mostly
        identical, remote PacketCluster nodes, which can be
        networked, don't see the difference between a generic
        PacketCluster node and CLX. So it fits well into an
        established network of PacketCluster nodes.

        CLX is not an user application, it is a network node
        software. As such it is not of much use for the
        individual amateur. SysOPs of PacketCluster nodes
        with some experience on both PacketCluster and
        Linux will find this application interesting.

        Here are some of the features of CLX
        
        -- It is fully compatible with the internal PCxx
           protocol and from a users' point of view. It
           allows multitasking and different priorities
           for different things.
        
        -- The software detects looping DX spots without
           generating endless messages. CLX filters out such
           duplicate information. We have implemented a
           concept which allows us to connect the network
           at multiple points, which would formerly have
           been called a "Cluster Loop". CLX knows of
           so-called "active" and "passive" links. The
           outcome is that more DX information is seen by
           CLX.
        
        -- An interface to call your external programs
           (even dialog programs).
        
        -- CLX uses modern programming concepts like
           shared memory for common data, lex & yacc to
           implement command language, shared libraries to
           keep binaries small (this is still on our wish
           list), remote procedure calls for inter process
           communication. It is strictly modularized with
           its own dedicated process for every major task.
        
        -- Here is a definition for each particular module
        
              con_ctl interfaces AX.25 kernel code and
                provides a socket for local users.
                
              rcv_ctl manages receive spooling.

              snd_ctl manages transmit spooling.
                
              rm_disp receive message dispatcher, forwards
                messages to other processes.
                
              usr_req user database requests, forks a
                db_(...) process for every database task to make it
                run in the background. The background process
                later sends the results directly to send_ctl.
                
              mb_ctl mailbox control. The mailbox keeps
                messages in a file system, header information
                is stored in the database.
                
              usr_ctl user administration (logins, logouts,
                logbook).
                
              usc_mng manages external user commands and
                command extensions.

              iu_com inter user communication (talk, conference).
                
              snd_ctl transmit spooling, handling priorities.
                
              icl_com inter node communication (processing and
                generating PCxx messages).
                
              clx_ctl system administration, installing shared
                memory pages.

              int_com manages CLX system communications.

              db_(...) serveral programs interfacing database access.
                When a query is started, one of them will be
                lauched. When the result is there, it will send it
                to the user.

              udt_mng user data table manager. A process which
                handles requests to private database tables,
                which could be imported from AK1A .ful databases.

              bbs_if an interface to external BBS systems for mail
                forwarding.

        --    Interactive applications:

              net_usr, interface program for incoming and outgoing
                calls.

              term_usr, more comforatble login program supporting 
                GNU readline which lets you recall and edit 
                commands.

              clx_adm, online monitor for controlling and watching
                link situation.
                
        --    Hardware requirements: PC Pentium 100 with 32 MB 
              RAM is recommended. About 500 MB disk space. 
              Access through AX.25 kernel code, WAMPES or TNT.
        
        First on-air experiments started in late May 1994 under the
        callsign DB0PV-6, which now has become DB0CLX. At this time,
        most of the commands of the traditional PacketCluster software
        have been implemented and the software has been tested
        by many local DXers of the Munich area.
        
        CLX is based on a data base system called PostgreSQL.
        It currently runs on Linux Version 2.0.36 at DB0CLX.
        Today, the CLX code consists of over 50,000 lines of
        C++ code.

Where and how to obtain it
        The software is available on the Internet in a
        binary distribution:

        ftp.funet.fi:/pub/ham/unix/Linux/cluster/clx

        The software comes with a pseudo callsign "xx0xx".
        This will allow you to install and test the software
        locally but you cannot put it on the air. The callsign
        is encrypted and read from the configuration file.
        To use CLX on the air, you will have to ask for
        an encrypted callsign string to be put into the
        config file. Please contact clx@dl6rai.muc.de for
        this.

        Generally, the software will be given away for free.
        However, we want to keep an oversight of who is using
        our software. This is why we are playing the encryption
        game.

Licensing/Copyright
        CLX is Copyright (c) by Franta Bendl (DJ0ZY). You may
        use this software for non-commercial purposes only.