.TH SNMP_CONFIG 5 "08 Mar 2010" VVERSIONINFO "Net-SNMP"

.SH NAME

snmp_config - handling of Net-SNMP configuration files

.SH 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.

.SH "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:

SYSCONFDIR/snmp,

DATADIR/snmp, LIBDIR/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.

.PP

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.

.PP

Applications will read persistent configuration files 

in the following order of preference:

.RS

.PP

file in 

.B SNMP_PERSISTENT_FILE

environment variable

.br

directories in 

.B SNMPCONFPATH

environment variable

.br

directory defined by 

.B

persistentDir 

snmp.conf variable

.br

directory in 

.B

SNMP_PERSISTENT_DIR 

environment variable

.br

default 

.B

PERSISTENT_DIRECTORY 

directory

.RE

.PP

Finally, applications will write persistent configuration files 

in the following order of preference:

.RS

.PP

file in 

.B SNMP_PERSISTENT_FILE

environment variable

.br

directory defined by 

.B

persistentDir 

snmp.conf variable

.br

directory in 

.B

SNMP_PERSISTENT_DIR 

environment variable

.br

default 

.B

PERSISTENT_DIRECTORY 

directory

.RE

.PP

Note:  When using SNMP_PERSISTENT_FILE, the filename should match the 

application name.  For example, /var/net-snmp/snmpd.conf.

.SH "CONFIGURATION FILE TYPES"

Each application may use multiple configuration files, which will

configure various different aspects of the application.  For instance, 

the SNMP agent

.RB ( 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 

.B -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.

.PP

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.

.SH "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:

.PP

.RS

dumpPacket true

.RE

.PP

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:

.PP

.RS

[snmp] dumpPacket true

.RE

.PP

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:

.PP

.RS

.nf

# make this file handle snmp.conf tokens:

[snmp]

dumpPacket true

logTimestamp true

# return to our original snmpd.conf tokens:

[snmpd]

rocommunity mypublic

.fi

.RE

.PP

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:

.PP

.RS

[snmp] defCommunity myCommunity

.RE

.PP

for a single directive, or

.PP

.RS

.nf

# make this file handle snmp.conf tokens:

[snmp]

defCommunity myCommunity

defVersion   2c

# return to our original snmpapp.conf tokens:

[snmpapp]

.fi

.RE

.PP

for multiple settings.

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

.SH COMMENTS

.PP

Any lines beginning with the character '#' in the configuration files

are treated as a comment and are not parsed.

.SH "INCLUDING OTHER CONFIGURATION FILES"

It is possible to include other configuration files for processing

during normal configuration file processing.:

.PP

.RS

.nf

# include site specific config

includeFile site.conf

.RE

.PP

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.

.PP

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

.PP

.RS

.nf

# include a all *.conf files in a directory

includeDir /etc/snmp/config.d

.RE

.PP

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.

.PP

The specified directory must be absolute directory path.

.SH "API INTERFACE"

.PP

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

.I netsnmp_config_api(3)

manual page.

.SH "SEE ALSO"

snmpconf(1),

netsnmp_config_api(3),

snmp.conf(5),

snmpd.conf(5)

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