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lat_intro(7) Miscellaneous Information Manual lat_intro(7) NAME lat_intro, lat - Local Area Transport (LAT) support DESCRIPTION The LAT protocol supports communications between host computer systems and terminal servers with terminals, PCs, printers, modems and other devices over local area networks (LAN). LAT software has the features required for a host to function as both a service node and a server node, so requests for connections can be made by server users and connections can be originated to other service nodes. The software also permits host applications to initiate connections to server ports, designated as application ports, to access remote de- vices. The DIGITAL UNIX LAT implementation is a STREAMS-based LAT driver. Types of Services DIGITAL UNIX supports the following types of LAT services: Bound inter- active services A bound interactive service that has specific LAT devices (ttys) bound to it. When connecting to this type of service, you are always logged onto a tty that was bound to this service by the latcp command. Unbound interactive services An unbound interactive service does not have specific LAT de- vices bound to it. When you access an unbound interactive ser- vice, the service uses any available LAT devices (ttys) that have not been bound to any other service. This is the default type of service that is added when LAT is started or when no ttys are bound to the service. If there is only one unbound interactive service on the system, you cannot delete it. Dedicated or optional services A dedicated or optional service is used with specialized appli- cations, written especially for LAT. The LAT/Telnet gateway is an example of a specialized application. The latcp(8) reference page provides information on the latcp commands used to create the different types of services. CONFIGURATION To set up LAT for use on your machine, install the LAT subset, OS- FLATxxx (where xxx is the DIGITAL UNIX version number), and perform the following tasks: Configure and reboot the kernel Set up the system for LAT Customize LAT on your system (optional) To do these tasks, you must log in as superuser. The following sections briefly explain these tasks. For more informa- tion, refer to the Network Administration and System Administration manuals. Kernel Configuration To configure the kernel for LAT, the system configuration file must contain the Data Link Bridge (DLPI Version 2.0 Service Class 1) option. For more information see the Network Administration manual. System Setup You can set up LAT on your system automatically by using the latsetup utility, or manually. Digital recommends that you use the latsetup utility to set up your system automatically. When you set up your system automatically, the latsetup utility per- forms the following functions: Creates the LAT device special files Adds or removes getty entries to or from the /etc/inittab file for in- coming connections Executes the init q command Starts or stops LAT ser- vices Enables or disables LAT automatic startup and shutdown For more information, see latsetup(8). If you want to set up LAT manually, refer to lat_manual_setup(7). User Customization You can use the latcp command to customize LAT on your system. When LAT automatic startup and shutdown is enabled, the /sbin/init.d/lat script is executed upon reaching run level 3. When this script is executed, it reads the /etc/latstartup.conf file (if this file exists) and executes the latcp commands in the file. If the following LAT parameters have not been set, the /sbin/init.d/lat script starts LAT with the default values: Node name -- The default value is the host name. Multicast timer -- The default value is 60 seconds. Network adapter -- The default is all network adapters connected to broadcast media. Service name -- The default value is taken from the LAT node name parameter. The following parameters are set to the defaults for each ser- vice, unless specified: Service description -- The default value is ``DIGITAL UNIX Version X.X LAT SERVICE.'' Rating -- The de- fault is dynamic rating. Group code -- The default value is 0. Agent status -- The default is disabled. Outgoing port groups -- The default is group 0. Maximum number of learned services -- The default value is 100. You can automate your LAT customization by creating a file called /etc/latstartup.conf and entering your LAT customization commands in this file. For example, you can define a particular node name or add service names. For more information on how to customize your system using a /etc/lat- startup.conf file, refer to the Network Administration manual and latcp(8). Note If your system is configured with multiple network adapters, you can specify that the LAT protocol run over the multiple adapters, provided they are connected to different logical networks. If you have more than one network adapter connected to a logical network, you should use the latcp to specify that the LAT protocol runs over only one adapter. Running LAT over more than one network adapter can cause unpredictable results. You can determine the adapters defined on your system by us- ing the netstat -i command. CHANGING LINE DISCIPLINES The DIGITAL UNIX LAT implementation is a STREAMS-based tty design. In prior versions of DIGITAL UNIX, the LAT implementation was a clist- based tty design. Therefore, the method for changing the LAT tty line discipline of a STREAMS-based LAT tty differs from that of a clist- based LAT tty. Your DIGITAL UNIX LAT system is configured (through the /etc/latauto- push.conf file) to automatically push the ldterm (POSIX line disci- pline) module upon opening a LAT terminal device (tty). When the open call completes successfully, the ldterm module is in place on the stream above the LAT driver. The Network Administration manual provides a sample program that demon- strates how terminal (tty) line disciplines are changed in a clist- based tty and a STREAMS tty environment. Additionally, you can use the strchg command to change the STREAMS configuration of the user's stan- dard input. For more information, see the autopush(8) and strchg(1) reference pages. FILES Specifies the SVR4 LAT device special files. (Where n is a number starting at 620 and having no upper limit.) Specifies the BSD LAT ter- minal devices. (Where W is a number from 0 to 9 and X is an alphanu- meric character from 0 to 9, a lowercase a to z, or an uppercase char- acter A to Z.) LAT supports up to 620 BSD LAT terminal devices. Spec- ifies the LAT control device. Specifies the LAT startup and shutdown script. Specifies LAT customization commands. Sets up the system database to automatically push the ldterm STREAMS module on top of the LAT STREAMS driver, each time a LAT tty is opened. Controls the ini- tialization process. Specifies the system configuration file. RELATED INFORMATION Commands: llogin(1), netstat(1), strchg(1), autopush(8), init(8), latcp(8), latsetup(8), MAKEDEV(8), rcmgr(8), strsetup(8). Files: inittab(4). Introduction: lat_manual_setup(7). Network Administration , System Administration delim off lat_intro(7)