MIB2C(1) Net-SNMP MIB2C(1)NAMEmib2c-- generate template code for extending the agent
SYNOPSISmib2c [-h] -c CONFIGFILE [-I PATH] [-f OUTNAME] [-i][-s][-q][-S
VAR=VAL] MIBNODE
DESCRIPTION
The mib2c tool is designed to take a portion of the MIB tree (as
defined by a MIB file) and generate the template C code necessary to
implement the relevant management objects within it.
In order to implement a new MIB module, three files are necessary:
- MIB definition file
- C header file
- C implementation file.
The mib2c tool uses the MIB definition file to produce the two C code
files. Thus, mib2c generates a template that you can edit to add logic
necessary to obtain information from the operating system or applica‐
tion to complete the module.
MIBNODE is the top level mib node you want to generate code for. You
must give mib2c a mib node (e.g. ifTable) on the command line, not a
mib file. This is the single most common mistake.
The mib2c tool accepts both SMIv1 and SMIv2 MIBs.
mib2c needs to be able to find and load a MIB file in order to generate
C code for the MIB. To enable mib2c to find the MIB file, set the MIBS
environment variable to include the MIB file you are using. An example
of setting this environment variable is:
MIBS=+NET-SNMP-TUTORIAL-MIB
or
MIBS=ALL
The first example ensures that mib2c finds the NET-SNMP-TUTORIAL-MIB
mib, in addition to the default MIB modules. The default list of MIB
modules is set when the suite is first configured and built and basi‐
cally corresponds to the list of modules that the agent supports. The
second example ensures that mib2c finds all MIBs in the search location
for MIB files. The default search location for MIB files is
/usr/share/snmp/mibs. This search location can be modified by the MIB‐
DIRS environment variable.
Both the MIB files to be loaded and the MIB file search location can
also be configured in the snmp.conf file. Please see snmp.conf(5) for
more information.
The generated *.c and *.h files will be created in the current working
directory.
OPTIONS-h Display a help message.
-c CONFIGFILE
Use CONFIGFILE when generating code. These files will be
searched for first in the current directory and then in the
/usr/share directory (which is where the default mib2c configu‐
ration files can be found). Running mib2c without the -c CON‐
FIGFILE option will display a description of the valid values
for CONFIGFILE, that is, the available config files, including
new ones that you might author.
For example,
% mib2c ifTable
will display a description of the currently available values for
CONFIGFILE.
The following values are supported for CONFIGFILE:
mib2c.mfd.conf
mib2c.scalar.conf
mib2c.int_watch.conf
mib2c.iterate.conf
mib2c.create-dataset.conf
mib2c.array-user.conf
mib2c.column_defines.conf
mib2c.column_enums.conf
GENERATING CODE FOR SCALAR OBJECTS:
If you're writing code for some scalars, run:
mib2c-c mib2c.scalar.conf MIBNODE
If you want to magically "tie" integer variables to integer
scalars, use:
mib2c-c mib2c.int_watch.conf MIBNODE
GENERATING CODE FOR TABLES:
The recommended configuration file for tables is the MIBs for
Dummies, or MFD, configuration file. It hides as much of the
SNMP details as possible, generating small, easy to understand
functions. It is also the most flexible and well documented
configuration file. See the agent/mibgroup/if-
mib/ifTable/ifTable*.c files for an example:
mib2c-c mib2c.mfd.conf MIBNODE
If your table data is kept somewhere else (e.g. it's in the ker‐
nel and not in the memory of the agent itself) and you need to
"iterate" over it to find the right data for the SNMP row being
accessed. See the agent/mibgroup/mibII/vacm_context.c file for
an example:
mib2c-c mib2c.iterate.conf MIBNODE
If your table data is kept in the agent (i.e. it's not located
in an external source) and is purely data driven (i.e. you do
not need to perform any work when a set occurs). See the
agent/mibgroup/examples/data_set.c file for an example of such a
table:
mib2c-c mib2c.create-dataset.conf MIBNODE
If your table data is kept in the agent (i.e. it's not located
in an external source), and you can keep your data sorted by the
table index but you do need to perform work when a set occurs:
mib2c-c mib2c.array-user.conf MIBNODE
GENERATING HEADER FILE DEFINITIONS
To generate just a header with a define for each column number
in your table:
mib2c-c mib2c.column_defines.conf MIBNODE
To generate just a header with a define for each enum for any
column containing enums:
mib2c-c mib2c.column_enums.conf MIBNODE
GENERATING CODE FOR THE 4.X LINE OF CODE (THE OLDER API)
mib2c-c mib2c.old-api.conf MIBNODE
-IPATH Search for configuration files in PATH. Multiple paths can be
specified using multiple -I switches or by using one with a
comma separated list of paths in it.
-f OUTNAME
Places the output code into OUTNAME.c and OUTNAME.h. Normally,
mib2c will place the output code into files which correspond to
the table names it is generating code for, which is probably
what you want anyway.
-i Do not run indent on the resulting code.
-s Do not look for MIBNODE.sed and run sed on the resulting code.
This is useful to shorten long mib variable names in the code.
-q Run in "quiet" mode, which minimizes the status messages mib2c
generates.
-SVAR=VAL
Preset a variable VAR, in the mib2c.*.conf file, to the value
VAL. None of the existing mib2c configuration files
(mib2c.*.conf) currently makes use of this feature, however, so
this option should be considered available only for future use.
EXAMPLES
The following generates C template code for the header and implementa‐
tion files to implement UCD-DEMO-MIB::ucdDemoPublic.
% mib2c-c mib2c.scalar.conf ucdDemoPublic
writing to ucdDemoPublic.h
writing to ucdDemoPublic.c
running indent on ucdDemoPublic.h
running indent on ucdDemoPublic.c
The resulting ucdDemoPublic.c and ucdDemoPublic.h files are generated
the current working directory.
The following generates C template code for the header and implementa‐
tion files for the module to implement TCP-MIB::tcpConnTable.
% mib2c-c mib2c.iterate.conf tcpConnTable
writing to tcpConnTable.h
writing to tcpConnTable.c
running indent on tcpConnTable.h
running indent on tcpConnTable.c
The resulting tcpConnTable.c and tcpConnTable.h files are generated in
the current working directory.
SEE ALSOsnmpcmd(1), snmp.conf(5)V5.7.2 05 Apr 2010 MIB2C(1)
