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<h1>Overview</h1>
Start by reading the <span style="font-weight: bold;">snmp_config</span>
manual page that describes how the
Net-SNMP configuration files operate and
how they all work together.&nbsp; Note:&nbsp; When using Windows, all
configuration files should be placed in the <span
 style="font-weight: bold;">(install
folder)\etc\snmp</span> folder.<br>
<br>
<span style="font-weight: bold;">Note:&nbsp; The Net-SNMP configuration
files generally contain sensitive
information such as passphrases and community strings so permissions
should be set to restrict who can read the files.</span><br
 style="font-weight: bold;">
<br>
A Perl script called snmpconf is included which can be used to
create configuration files.&nbsp; Full documentation on using snmpconf
is available in the 'Applications' section.<br>
<br>
To run snmpconf, use the following command line:<br>
<br>
<span style="font-family: monospace; font-weight: bold;">snmpconf -i</span><br>
<h2>Environment / registry variables<br>
</h2>
During compilation of Net-SNMP, the default search path for
configuration files is set to a value which under Windows is normally <span
 style="font-weight: bold;">c:/usr/etc/snmp</span>.&nbsp; Similarly the
default share path is set to <span style="font-weight: bold;">c:/usr/share/snmp</span>.&nbsp;
The conf path is used to locate configuration files such as <span
 style="font-weight: bold;">snmp.conf</span>, <span
 style="font-weight: bold;">snmpd.conf</span> etc, and the share path
is used by programs such as <span style="font-weight: bold;">snmpconf </span>and
<span style="font-weight: bold;">mib2c</span> to store supporting files.<br>
<br>
As explained in the <span style="font-weight: bold;">snmp_config</span>
manual, the default search path can be changed by modifying the <span
 style="font-weight: bold;">SNMPCONFPATH </span>environment
variable.&nbsp; Similarly, the default share path can be set by
modifying the <span style="font-weight: bold;">SNMPSHAREPATH </span>environment
variable.&nbsp; <br>
<br>
There are two ways to set Net-SNMP environment variables under
Windows.&nbsp; The first way is to simply set the environment variable
using the System Control Panel (<span style="font-weight: bold;">Advanced</span>
tab - <span style="font-weight: bold;">Environment variables</span>).&nbsp;
The environment variables can be defined as either <span
 style="font-weight: bold;">System </span>or <span
 style="font-weight: bold;">User </span>specific.&nbsp; <span
 style="font-weight: bold;">System </span>is the recommended choice as
it allows the variable to be used by all users.<br>
<br>
The second and preferred way is to add the environment variables as
string values (REG_SZ) to the registry under the
HKEY_LOCAL_MACHINE\Software\Net-SNMP or the
HKEY_CURRENT_USER\Software\Net-SNMP key.&nbsp; Creating a string value
with the environment variable name and assigning a string value to it
is equivalent to defining the environment variable.&nbsp; This is a
feature of Net-SNMP and not a standard Windows feature.&nbsp; Any
environment variable used by Net-SNMP can be defined this way; it is
not limited to just <span style="font-weight: bold;">SNMPCONFPATH</span>
and <span style="font-weight: bold;">SNMPSHAREPATH</span>.<br>
<br>
For example, if Net-SNMP was compiled to use <span
 style="font-weight: bold;">c:\usr</span> (such as the Windows binary
available from the Net-SNMP site), but it was installed in the folder <span
 style="font-weight: bold;">c:\Net-SNMP</span>, then the following
environment variables or registry keys must be created so that the
applications know where to find the configuration and supporting files:<br>
<br>
Method 1: Environment variables:<br>
<ul>
  <li>SNMPCONFPATH=c:/Net-SNMP/etc/snmp;c:/Net-SNMP/snmp/persist</li>
  <li>SNMPSHAREPATH=c:/Net-SNMP/share/snmp</li>
</ul>
Method 2: Registry:<br>
<ul>
  <li>HKEY_LOCAL_MACHINE\Software\Net-SNMP\SNMPCONFPATH=c:/Net-SNMP/etc/snmp;c:/Net-SNMP/snmp/persist</li>
  <li>HKEY_LOCAL_MACHINE\Software\Net-SNMP\SNMPSHAREPATH=c:/Net-SNMP/share/snmp</li>
</ul>
During the installation of the Windows binary from the Net-SNMP site,
the installer automatcially creates the following registry keys:<br>
<ul>
  <li>HKEY_LOCAL_MACHINE\Software\Net-SNMP\SNMPCONFPATH=(install
  folder)/etc/snmp;(install folder)/snmp/persist</li>
  <li>HKEY_LOCAL_MACHINE\Software\Net-SNMP\SNMPSHAREPATH=(install
folder)/share/snmp</li>
</ul>
<div style="margin-left: 40px;"></div>
If Net-SNMP is installed in a folder other than the default <span
 style="font-weight: bold;">c:\usr</span> folder, then the above
registry keys or environment variables must match, and the <span
 style="font-weight: bold;">snmp.conf</span>
file must contain a definition for <span style="font-weight: bold;">mibdirs</span>,
<span style="font-weight: bold;">persistentDir </span>and <span
 style="font-weight: bold;">tempFilePattern</span>.&nbsp; For example,
if Net-SNMP was installed in <span style="font-weight: bold;">c:\Net-SNMP</span>,
the snmp.conf file must contain:<br>
<br>
<div style="margin-left: 40px; font-family: monospace;">mibdirs
c:/net-snmp/share/snmp/mibs<br>
persistentDir c:/net-snmp/snmp/persist<br>
tempFilePattern c:/net-snmp/temp/snmpdXXXXXX<br>
</div>
<p>The registry is the recommended method for defining the <span
 style="font-weight: bold;">SNMPCONFPATH </span>and <span
 style="font-weight: bold;">SNMPSHAREPATH </span>variables.&nbsp; Due
to a
limitation in the Windows Service Control Manager (SCM), if any system
environment variables are changed, the system will need to be rebooted
to allow the services to access the changed environment variables (see
Microsoft knowledge base article 821761).&nbsp; Therefore, when running
<span style="font-weight: bold;">snmpd </span>or <span
 style="font-weight: bold;">snmptrapd </span>as a service, if <span
 style="font-weight: bold;">SNMPCONFPATH</span> or <span
 style="font-weight: bold;">SNMPSHAREPATH</span>
is changed, a reboot will be required after setting the environment
variables, otherwise the services may fail to start.&nbsp; Using the
registry to store the environment variables eliminates this problem.<br>
</p>
<p><b>Note1: All paths contained in
configuration files must use forward
slashes (Unix convention), NOT back
slashes.</b></p>
<p><b>Note2:</b> HKEY_CURRENT_USER can be used instead of
HKEY_LOCAL_MACHINE if desired. All applications will search for
SNMPCONFPATH and SNMPSHAREPATH (and any other variable normally defined
as an environment variable) in the following order:<br>
</p>
<ul>
  <li>Environment space</li>
  <li>HKEY_CURRENT_USER\Software\Net-SNMP\</li>
  <li>HKEY_LOCAL_MACHINE\Software\Net-SNMP\</li>
</ul>
<p></p>
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