NAME

       snmp_config - handling of Net-SNMP configuration files

DESCRIPTION

       The  Net-SNMP  package  uses various configuration files to configure its applications.  This manual page
       merely describes the overall nature of them, so that the other manual pages don't have to.

DIRECTORIES SEARCHED

       First off, there are numerous places that configuration files can be found and read  from.   By  default,
       the  applications  look  for  configuration  files  in  the following 4 directories, in order: /etc/snmp,
       /usr/share/snmp, /usr/lib/i386-linux-gnu/snmp, and $HOME/.snmp.  In each of these directories,  it  looks
       for files with the extension of both conf and local.conf (reading the second ones last).  In this manner,
       there are 8 default places a configuration file can exist for any given configuration file type.

       Additionally,  the  above  default  search  path  can  be  overridden by setting the environment variable
       SNMPCONFPATH to a colon-separated list of directories to search for.  The path for  the  persistent  data
       should be included when running applications that use persistent storage, such as snmpd.

       Applications will read persistent configuration files in the following order of preference:

              file in SNMP_PERSISTENT_FILE environment variable
              directories in SNMPCONFPATH environment variable
              directory defined by persistentDir snmp.conf variable
              directory in SNMP_PERSISTENT_DIR environment variable
              default /var/lib/snmp directory

       Finally, applications will write persistent configuration files in the following order of preference:

              file in SNMP_PERSISTENT_FILE environment variable
              directory defined by persistentDir snmp.conf variable
              directory in SNMP_PERSISTENT_DIR environment variable
              default /var/lib/snmp directory

       Note:   When  using  SNMP_PERSISTENT_FILE,  the filename should match the application name.  For example,
       /var/net-snmp/snmpd.conf.

CONFIGURATION FILE TYPES

       Each application may use multiple configuration files, which will configure various different aspects  of
       the  application.   For instance, the SNMP agent (snmpd) knows how to understand configuration directives
       in both the snmpd.conf and the snmp.conf files.  In fact, most applications understand how  to  read  the
       contents of the snmp.conf files.  Note, however, that configuration directives understood in one file may
       not  be  understood  in another file.  For further information, read the associated manual page with each
       configuration file type.  Also, most of the applications support a -H switch on  the  command  line  that
       will list the configuration files it will look for and the directives in each one that it understands.

       The  snmp.conf  configuration  file  is  intended  to be a application suite wide configuration file that
       supports directives that  are  useful  for  controlling  the  fundamental  nature  of  all  of  the  SNMP
       applications, such as how they all manipulate and parse the textual SNMP MIB files.

SWITCHING CONFIGURATION TYPES IN MID-FILE

       It's  possible  to  switch  in mid-file the configuration type that the parser is supposed to be reading.
       Since that sentence doesn't make much sense, lets give you an example: say that you  wanted  to  turn  on
       packet  dumping  output  for  the  agent  by  default, but you didn't want to do that for the rest of the
       applications (ie, snmpget, snmpwalk, ...).  Normally to enable packet dumping in the  configuration  file
       you'd need to put a line like:

              dumpPacket true

       into  the  snmp.conf file.  But, this would turn it on for all of the applications.  So, instead, you can
       put the same line in the snmpd.conf file so that it only applies to the snmpd daemon.  However, you  need
       to tell the parser to expect this line.  You do this by putting a special type specification token inside
       a  []  set.   In  other words, inside your snmpd.conf file you could put the above snmp.conf directive by
       adding a line like so:

              [snmp] dumpPacket true

       This tells the parser to parse the above line as if it  were  inside  a  snmp.conf  file  instead  of  an
       snmpd.conf  file.   If  you  want  to  parse  a bunch of lines rather than just one then you can make the
       context switch apply to the remainder of the file or until the next context switch directive  by  putting
       the special token on a line by itself:

              # make this file handle snmp.conf tokens:
              [snmp]
              dumpPacket true
              logTimestamp true
              # return to our original snmpd.conf tokens:
              [snmpd]
              rocommunity mypublic

       The  same  approach  can  be used to set configuration directives for a particular client application (or
       group of applications).  For example, any program  that  uses  the  'snmp_parse_args()'  call  to  handle
       command-line  arguments  (including  the  standard  command-line  tools  shipped  as part of the Net-SNMP
       distributions) will automatically read the config file 'snmpapp.conf'.  To set library-level settings for
       these applications (but not other more-specific tools), use configuration such as the following:

              [snmp] defCommunity myCommunity

       for a single directive, or

              # make this file handle snmp.conf tokens:
              [snmp]
              defCommunity myCommunity
              defVersion   2c
              # return to our original snmpapp.conf tokens:
              [snmpapp]

       for multiple settings.  Similarly for any other application token (as passed to init_snmp()).

COMMENTS

       Any lines beginning with the character '#' in the configuration files are treated as a  comment  and  are
       not parsed.

INCLUDING OTHER CONFIGURATION FILES

       It  is  possible  to  include  other  configuration files for processing during normal configuration file
       processing.:

              # include site specific config
              include site.conf

       This will search every directory in the configuration path for files
       named site.conf, and will process those files before returning to the
       processing of the original file. Note that if '.conf' is omitted,
       it will be appended. That is, all configuration files must end
       in '.conf'.

API INTERFACE

       Information about writing C code that makes use of this system in either the agent's MIB  modules  or  in
       applications can be found in the netsnmp_config_api(3) manual page.

SEE ALSO

       snmpconf(1), netsnmp_config_api(3), snmp.conf(5), snmpd.conf(5)

V5.7.2                                             08 Mar 2010                                    SNMP_CONFIG(5)