HP OpenVMS Systems Documentation

You can configure SNMP in three ways, which can be used in combination:

• Using the standard TCPIP$CONFIG.COM procedure and the SET CONFIGURATION SNMP command. These methods write configuration information into the TCP/IP Services configuration database file TCPIP$CONFIGURATION.DAT. Section 14.4.1 describes how to use TCPIP$CONFIG to initially configure SNMP.
• Editing the text configuration file TCPIP$VMS_SNMP_CONF.DAT, located in the SYS$SYSDEVICE:[TCPIP$SNMP] directory. This method provides options not available with TCPIP$CONFIG and with the SET CONFIGURATION SNMP command.

  Note 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.

  
  The configuration file is described in Section 14.4.3.
• Assigning logical names. This method provides the same options as the text configuration file. For more information, see Section 14.4.3.

If the same option is defined in multiple ways, the configuration methods are resolved as follows:

• Values specified through TCPIP$CONFIG or SET CONFIGURATION SNMP take precedence over any options specified in the TCPIP$VMS_SNMP_CONF.DAT file or set with logical names.
• Values specified in the TCPIP$VMS_SNMP_CONF.DAT file take precedence over logical name settings.

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.

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 HP TCP/IP Services for OpenVMS Management Command Reference manual.

• The name of the person to contact about the system. For example:

  TCPIP> SET CONFIGURATION SNMP/CONTACT="Sam Spade"

• The physical location of the system. For example:

  TCPIP> SET CONFIGURATION SNMP - _TCPIP> /LOCATION=(FIRST="Falcon Building",SECOND="Los Angeles, CA")

• The community information used to authenticate requests from a network manager and to determine the addresses to which trap messages are sent.
  SNMP network management clients are grouped into communities as specified in RFC 1157. You can define one or more communities, which your master agent uses to authenticate requests.
  The parameters you specify for each community are as follows:
  • Community name
    The name associated with the community. The standard community is "public." You can choose not to provide this community name when you run TCPIP$CONFIG. Answer no to the question "Do you want to provide the public community." If you disable the public community, you might need to reconfigure SNMP clients in your environment.
    Community names are case sensitive. When you use TCPIP$CONFIG to specify a community name, do not use quotation marks to preserve the case; the case is preserved exactly as you enter it. However, if you customize your existing SNMP configuration using the SET CONFIGURATION SNMP command, make sure you enclose the community name in quotation marks to preserve the case. If you do not enclose the community name in quotation marks, the name is changed to all uppercase.
    The community name must be a string of alphanumeric characters. You cannot include a space or other nonalphanumeric character in the community name.
    You can also modify the community name using the community option in the configuration file, as described in Table 14-4.

  • Community address
    The address associated with the community. One community name can have multiple addresses in its entry. For example:

    TCPIP> SET CONFIGURATION SNMP /ADDRESS=(6.10.1.2,100.2.2.1)

    
    Specifying address 0.0.0.0 for READ and WRITE allows any host the type of access specified. To allow any network manager to monitor your system remotely, specify the standard community name ( public , in lowercase letters) with address 0.0.0.0. For example:

    TCPIP> SET CONFIGURATION SNMP /COMMUNITY="public" /ADDRESS=0.0.0.0

    
    Traps are sent to UDP port 162 on hosts for all trap addresses regardless of community name. The use of address 0.0.0.0 on a trap means that traps are not sent unless another address is also specified.
  • Types of access
    The types of access associated with the community are described in the following table:

    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. If you want to display the addresses that the agent recognizes as members of the community, use the /FULL qualifier. For example:

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 9.20.208.53

trapit              Read Trap  9.20.208.53, 9.20.208.100

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 9.20.208.53 through the writeit community. In addition, trap messages are sent to UDP port 162 on hosts 9.20.208.53 and 9.20.208.100.

Alternatively, you can display the configuration options in the SNMP configuration text file described in Section 14.4.3. For more information, see Section 14.6.5.2.

14.4.3 SNMP Options

You can configure the way SNMP runs by entering SNMP options into the SNMP configuration file TCPIP$VMS_SNMP_CONF.DAT.

When it starts, the SNMP master agent creates the temporary file SYS$SYSDEVICE:[TCPIP$SNMP]TCPIP$TMP_SNMP_CONF.DAT from data in the standard TCP/IP configuration database file TCPIP$CONFIGURATION.DAT. For troubleshooting purposes, a few versions of this file are preserved. The master agent appends this temporary file to TCPIP$VMS_SNMP_CONF.DAT to produce the master configuration file TCPIP$SNMP_CONF.DAT.

When the standard OS_MIBS and HR_MIB subagents start up, they read TCPIP$SNMP_CONF.DAT. Only the master agent and these standard subagents use values in the text files.

By default, custom subagents do not take advantage of the configuration options. To take advantage of these options, you must assign a logical that is visible to the subagent process. The following example shows how to define TCPIP$SNMP_GEN_LOGFILE logical to set the snmp_gen_logfile configuration option:

$ ASSIGN/SYSTEM 1 TCPIP$SNMP_GEN_LOGFILE

If a configuration option is not handled by the eSNMP API, the subagent must include an explicit genenv() or similar call to access the value of the option.

14.4.3.1 Using Logical Names to Configure SNMP

Most configuration options have a corresponding logical name. In some cases, you can define system logical names as an alternative to entering a value in the text file. For a list of the options and their associated logical names, see Section 14.4.3.4.

14.4.3.2 Dynamic Options

Some options are available for you to change dynamically; that is, without shutting down and restarting the SNMP service. To change configuration values dynamically, you can do one of the following:

• Define the appropriate logical name.
• Edit the configuration file, then define snmp_signal to be sighup . Be sure to deassign snmp_signal afterwards to prevent continuous rereading of the configuration file.

The master agent and the subagents convert lines in the configuration file that begin with the OpenVMS-specific config command to user-mode process logicals by adding the prefix TCPIP$. For example, SNMP_GEN_LOGFILE becomes TCPIP$SNMP_GEN_LOGFILE. (This mechanism does not apply to options with other keywords, such as trap .) Because the logicals are local to agent processes, they are not visible to a DCL command SHOW LOGICAL issued in another process.

If there are lines with duplicate configuration tags, the last line supersedes all others. Because the temporary file TCPIP$TMP_CONF.DAT (described in Section 14.4.3) is appended after the user-editable TCPIP$VMS_SNMP_CONF.DAT file, the standard TCPIP configuration values from that temporary file always supersede those from the user-edited file.

Lines in the configuration file that begin with a pound sign (#) are ignored. The pound sign is the comment character.

Option names and values are not case sensitive. Boolean values are considered on if the option is present with no value. Otherwise, they are considered off. Thus, to turn off an option that was enabled at startup, you must specify zero as the value.

If you specify a value that is longer than the limit, the value is converted to hexadecimal and then truncated. For example, if you specify the value 257 in place of an 8-bit unsigned value, it is converted to hexadecimal (0101) and truncated to 1.

14.4.3.4 SNMP Configuration Options

Most of the SNMP options set in the TCPIP$VMS_SNMP_CONF.DAT file must be entered using the following syntax:

config option-name value

There are several types of SNMP configuration options:

• Logging options, described in Table 14-3. These options control the way messages are logged.
• Operation options, described in Table 14-4. These options control the operational settings for SNMP. Some of these options cannot be set by using a logical name.
• Timing options, described in Table 14-5. These options control the way timeouts are handled.
• Testing and troubleshooting options, described in Table 14-6. These options are useful when you are testing SNMP functions and troubleshooting subagent problems.
• Backward-compatibility options, described in Table 14-7. These options are available to provide compatibility with subagents developed under previous versions of SNMP.

Except for the community name, option values are not case sensitive.