HP OpenVMS Systems Documentation
Compaq TCP/IP Services for OpenVMS
options send the query to the specified host immediately. If you omit
the host names, the default is the local host. To enter interactive
mode, specify the
12.9 Solving NTP Problems
Some common NTP problems include:
The Simple Network Management Protocol (SNMP) is network management technology that facilitates the management of a TCP/IP network or internet in a vendor-independent manner. SNMP enables a network administrator to manage the various network components using a set of well-known procedures understood by all components, regardless of the vendor that manufactured them.
Configuring SNMP on your OpenVMS system allows a remote SNMP management client to obtain information about your host and to set system and network parameters.
This chapter reviews key concepts of SNMP and describes:
For information about writing programs using SNMP, refer to the
Compaq TCP/IP Services for OpenVMS SNMP Programming and Reference guide.
13.1 Key Concepts
Systems using SNMP are divided into two categories:
The management console is the system that issues a query; the agents run on the system being queried. Queries are sent and received in the form of protocol data units (PDUs) inside SNMP messages, which are carried in user data protocol (UDP) datagrams.
You can configure your host so that an SNMP client can obtain information about your host and perform updates on your host's management information base (MIB) data items. For example, you can configure your host to:
TCP/IP Services provides an SNMP master agent, two subagents (MIB II and Host Resources MIB), a MIB converter and compiler, a simple MIB browser, and MIB utility programs. Each subagent contains routines that perform read and write operations on its MIB data items.
Table 13-1 describes the SNMP components and the sample code supplied for custom subagent development.
|Master agent SNMP Version 2||
Process name: TCPIP$SNMP_
n is the number of times that the master agent has been
started since the SNMP service was enabled.
Keeps track of managed objects and allows objects to register themselves. Sends information about these objects to remote SNMP management consoles. Also maintains a small set of variables for the MIB II component.
Process name: TCPIP$OS_MIBS.
Provides information about the TCP/IP protocol stack and other network activity.
|Host resources MIB||
Process name: TCPIP$HR_MIB.
Provides information about the host system.
|MIB converter||Extracts a MIB definition in ASN.1 notation into a MIB definition (.MY) file.|
|MIB compiler||Compiles MIB-definition files (for example, CHESS_MIB.MY) into source code templates for use in building subagents.|
|SNMP utility programs||Acts as a simple clients to obtain a set of values for a MIB and to listen for and send trap messages. For information about using the MIB utility programs, see the Compaq TCP/IP Services for OpenVMS SNMP Programming and Reference guide.|
|SNMP subagent example||Implements an example based on the chess game; includes executable and source code.|
The TCPIP$CONFIG procedure sets up the SNMP UDP-based service at well-known port 161.
In addition, TCPIP$CONFIG sets up required files in the SYS$SYSDEVICE:[TCPIP$SNMP] directory.
The SNMP startup procedure (SYS$STARTUP:TCPIP$SNMP_STARTUP.COM) runs from the general TCPIP$STARTUP.COM procedure or can be run directly by the system manager.
TCPIP$SNMP_STARTUP.COM does the following:
To ensure compatibility with previous versions of TCP/IP Services, TCPIP$SNMP_SYSTARTUP.COM in turn runs SYS$SYSDEVICE:[TCPIP$SNMP]TCPIP$EXTENSION_MIB_STARTUP.COM, which installs and adjusts privileges for any additional, user-written subagents.
On startup, the TCP/IP Services kernel runs the TCPIP$SYSTEM:TCPIP$SNMP_RUN.COM procedure, which does the following:
As each subagent starts, it makes itself known to the master agent, a sequence that includes registering the MIB subtrees that the subagent maintains and communicating the port number on which it listens.
The SNMP shutdown procedure TCPIP$SNMP_SHUTDOWN.COM runs either from the general shutdown procedure TCPIP$SHUTDOWN.COM or can be run directly by the system manager.
TCPIP$SNMP_SHUTDOWN.COM does the following:
To ensure compatibility with previous versions, this procedure in turn
runs SYS$SYSDEVICE:[TCPIP$SNMP]TCPIP$EXTENSION_MIB_SHUTDOWN.COM, which
stops any additional subagent processes and deinstalls their images, if
13.1.2 Ensuring Access to Mounted Data
If the proxy setup between the SNMP server and the NFS server is not correct, the Host Resources MIB subagent cannot access data that has been mounted.
To ensure access to mounted data, set up a proxy to an anonymous user
(for example, to TCPIP$NOBODY) on the NFS server system. For more
information about adding proxy entries, see Chapter 20.
13.2 Managing the SNMP Service
The following command procedures are supplied to allow you to start up and shut down the SNMP service independently of TCP/IP Services:
Both the startup and shutdown procedures invoke the appropriate TCPIP$EXTENSION_MIB_*.COM file to ensure compatibility with previous versions of TCP/IP Services.
These files might be overwritten when you install subsequent versions of the TCP/IP Services product. For more information about these procedures, see Section 13.1.1.
To maintain site-specific SNMP logical names, commands, and parameter settings, you can create the following files:
Installing this version of TCP/IP Services will:
To preserve earlier versions of these files, copy them to another
directory. New versions of TCP/IP Services will include instructions for
merging the contents of the old versions with the current one.
13.3 Verifying the SNMP Installation
A separate installation verification procedure (IVP) exists for SNMP. To verify your configuration, complete these steps:
$ RUN SYS$COMMON:[SYSTEST.TCPIP]TCPIP$SNMPIVP.EXE
Table 13-2 lists the names of the primary SNMP executable and command files and their locations. For a list of files that help you build your own subagent, see the Compaq TCP/IP Services for OpenVMS SNMP Programming and Reference guide.
|TCPIP$ESNMP_SERVER.EXE||SYS$SYSTEM||Master agent image.|
|TCPIP$OS_MIBS.EXE||SYS$SYSTEM||MIB II subagent image.|
|TCPIP$HR_MIB.EXE||SYS$SYSTEM||Host Resources MIB subagent image.|
|TCPIP$SNMP_REQUEST.EXE||SYS$SYSTEM||Simple MIB browser.|
|TCPIP$SNMP_TRAPSND.EXE||SYS$SYSTEM||Program for sending trap messages.|
|TCPIP$SNMP_TRAPRCV.EXE||SYS$SYSTEM||Program for receiving trap messages.|
|TCPIP$ESNMP_SHR.EXE||SYS$SHARE||Routines in the eSNMP application programming interface (API).|
|TCPIP$SNMP_STARTUP.COM||SYS$STARTUP||Installs master and subagent images and runs TCPIP$SNMP_RUN.COM.|
|TCPIP$SNMP_RUN.COM||TCPIP$SYSTEM||Starts the master agent and subagents.|
|TCPIP$SNMP_SHUTDOWN.COM||SYS$STARTUP||Stops the master agent and subagents.|
|TCPIP$SNMP_SYSTARTUP.COM||SYS$STARTUP||Sets site-specific configuration values on startup.|
|TCPIP$SNMP_SYSHUTDOWN.COM||SYS$STARTUP||Sets site-specific configuration values on shutdown.|
|SYS$SYSDEVICE:[TCPIP$SNMP]||Starts custom subagents.|
|SYS$SYSDEVICE:[TCPIP$SNMP]||Shuts down custom subagents.|
|TCPIP$VMS_SNMP_CONF.DAT||SYS$SYSDEVICE:[TCPIP$SNMP]||User-editable configuration data file.|
|TCPIP$SNMP_CONF.DAT||SYS$SYSDEVICE:[TCPIP$SNMP]||Configuration data file used in the startup of the master agent and standard subagents.|
You can configure SNMP in three ways, which may be used in combination:
Although the OpenVMS SNMP configuration file is based on the UNIX implementation, there are several important differences. For example, the option snmpEnableAuthenTraps is not used. See the description of specific options for details.
If the same option is defined in multiple ways, the configuration methods are resolved as follows:
SNMP runs as a TCP/IP service. To be sure all SNMP-related files are included and enabled properly, run the TCPIP$CONFIG configuration procedure to configure SNMP initially or to set up a new configuration. When you enable SNMP during TCPIP$CONFIG, the procedure prompts you for the correct parameters.
You cannot use TCPIP$CONFIG to modify your existing SNMP configuration; TCPIP$CONFIG is intended only to set up a new SNMP configuration.
To modify the current SNMP configuration (for example, to specify an additional community name and address), you must enter the SET CONFIGURATION SNMP command with applicable qualifiers.
When you run TCPIP$CONFIG after a TCP/IP Services upgrade, be sure to disable and then reenable the SNMP service.
You supply the following information about your host when you configure SNMP initially during TCPIP$CONFIG or when you issue the SET CONFIGURATION SNMP command to modify your existing SNMP configuration. For detailed information about the SET CONFIGURATION SNMP command and qualifiers, see the Compaq TCP/IP Services for OpenVMS Management Command Reference manual.
TCPIP> SET CONFIGURATION SNMP/CONTACT="Sam Spade"
TCPIP> SET CONFIGURATION SNMP - _TCPIP> /LOCATION=(FIRST="Falcon Building",SECOND="Los Angeles, CA")
TCPIP> SET CONFIGURATION SNMP /ADDRESS=(126.96.36.199,188.8.131.52)
TCPIP> SET CONFIGURATION SNMP /COMMUNITY="public" /ADDRESS=0.0.0.0
|Access Type||Allows the Master Agent and Subagent to...|
|READ||Respond to a client's read requests (gets) for network information. Default. Members of a read-only community do not have write access to the SNMP MIB objects.|
|TRAP||Send alert messages (traps) to a client as a result of unusual events. For example, a trap message is sent to the client as a result of a get request that specifies an unauthorized community string ( authenticationFailure ).|
|WRITE||Process client write requests (sets) on your host's MIB data items.|
For example, to allow the master agent to respond to client get requests, enter:
TCPIP> SET CONFIGURATION SNMP /COMMUNITY="public" /TYPE=READ
To configure your host to allow client set requests, use the /FLAGS=SETS qualifier. For example:
TCPIP> SET CONFIGURATION SNMP /COMMUNITY="public" /FLAGS=SETS
To display configuration information in the SNMP configuration database, use the SHOW CONFIGURATION SNMP command. Use the /FULL qualifier if you want to display the addresses that the agent recognizes as members of the community. For example, enter:
TCPIP> SHOW CONFIGURATION SNMP /FULL SNMP Configuration Flags: AuthenTraps Sets Contact: Sam Spade Location First: Falcon Building Second: Los Angeles, CA Community Type address_list public Read 0.0.0.0 writeit Read Write 184.108.40.206 trapit Read Trap 220.127.116.11, 18.104.22.168
In this example, the configuration allows read access to any client on any host through the "public" community and read/write access to the client on host 22.214.171.124 through the "writeit" community. In addition, trap messages are sent to UDP port 162 on hosts 126.96.36.199 and 188.8.131.52.