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/x86_64-linux-gnu/snmp, and $HOME/.snmp.  In
       each of these directories, it looks for files snmp.conf, snmpd.conf and/or snmptrapd.conf,
       as well as snmp.local.conf, snmpd.local.conf and/or snmptrapd.local.conf. *.local.conf are
       always read 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
              includeFile site.conf

       This will load the specified configuration file. The
       path to file must be either absolute, starting with '/',
       or relative. The relative path is then relative to the directory
       where the parent file with 'includeFile' directive resides.

       The included file name does not need to have '.conf' suffix.

              # include a all *.conf files in a directory
              includeDir /etc/snmp/config.d

       This will search specified directory for all files with '.conf'
       suffix and process them as if they were included using includeFile
       directive. The configuration files are not processed in any particular
       order.

       The specified directory must be absolute directory path.

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)