what are MIBs in php?

Question

When I use this code in PHP:

print_r($_SERVER);

the first index that it prints is:

[MIBDIRS] => C:/xampp/php/extras/mibs

Can somebody tell me what is MIB-Directory ? and what is used for ?

Answer 1

From my research, I have found:

A management information base (MIB) is a database used for managing the entities in a communication network. Most often associated with the Simple Network Management Protocol (SNMP), the term is also used more generically in contexts such as in OSI/ISO Network management model. While intended to refer to the complete collection of management information available on an entity, it is often used to refer to a particular subset, more correctly referred to as MIB-module.¹

There is a PHP package Net-SNMP, which when enabled, will allow a user to call functions like snmp_read_mib() that will read MIB files.

snmp_read_mib

Reads and parses a MIB file into the active MIB tree

bool snmp_read_mib ( string $filename )

This function is used to load additional, e.g. vendor specific, MIBs so that human readable OIDs like VENDOR-MIB::foo.1 instead of error prone numeric OIDs can be used.

The order in which the MIBs are loaded does matter as the underlying Net-SNMP libary will print warnings if referenced objects cannot be resolved.

Note that $_SERVER contains environment variables:

$_SERVER -- $HTTP_SERVER_VARS [removed] — Server and execution environment information²

And in the User Contributed Notes for snmp_read_mib(), the top post is:

If you are trying to import mibs with dependencies on other mibs you will have to set the MIBDIRS environment variable.

Unix / Linux: export MIBDIRS=/home/<user>/MIBS:/usr/share/snmp/mibs
Window: Good luck! No really. Try this url out. It has everything that you need to know about setting environment vars in windows.

http://vlaurie.com/computers2/Articles/environment.htm
³

I just installed the latest version of (32-bit) XAMPP for Windows with PHP version 7.1.1. Looking in C:\xampp\apache\conf\extra\httpd-xampp.conf (one of the main Apache configuration files) I see on line 6:

SetEnv MIBDIRS "C:/xampp/php/extras/mibs"

So that sets the environment variable for PHP, which is why you see MIBDIRS in $_SERVER.

Perhaps the MIBDIRS from $_SERVER would be used like this:

snmp_read_mib($_SERVER['MIBDIRS'].'IPV6-TC.txt');

I was hoping to see an example in this question or its answers but didn't see any.

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¹_{https://en.wikipedia.org/wiki/Management_information_base}

²_{http://php.net/manual/en/reserved.variables.server.php}

³_{http://php.net/manual/en/function.snmp-read-mib.php#81586}