SNMP_VACM(3)

💖 NAME 💖

Welcome to SNMP_VACM(3), a Library Functions Manual page, bestie! The star of the show is snmp_vacm — the View-based Access Control module for bsnmpd(1). It's giving access-control royalty, no cap. 👑

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🎀 LIBRARY 🎀

The module-path situation is literally this:

(begemotSnmpdModulePath."vacm" = /usr/lib/snmp_vacm.so)

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✨ DESCRIPTION ✨

Okay so snmp_vacm implements the SNMPv3 View-based Access Control Model MIB as defined in RFC 3415. That's the whole assignment. 💅

It's the module used to manage the internal lists of SNMPv1, v2c and v3 user names and groups, plus their access rights to fetch or modify the values of the MIB objects maintained by bsnmpd and the modules loaded in the daemon.

This module must be loaded for bsnmpd to implement proper view-based access control. If the module is not loaded, access is granted to all configured SNMPv1 & SNMPv2c communities and SNMPv3 USM users. Like, all of them. 🫶

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🛠️ IMPLEMENTATION NOTES 🛠️

An entry in any table implemented by this MIB may be created by setting the relevant RowStatus column to createAndGo (4) — and fr fr, any other value for those columns in a SET operation will cause an error. 🚨

When an entry is created, any of its columns that is not used as index is set to the default value as specified in the SNMP-VIEW-BASED-ACM-MIB.

All entries maintained by the module are persistent after reboot if created via bsnmpd 's config file. Otherwise, entries created via SNMP are lost after reboot. 😭

A short description of the objects in the MIB follows:

• vacmContextTable — a read-only table that consists of a list of SNMP contexts available in bsnmpd.
• vacmSecurityToGroupTable — the table contains a list of SNMPv1, v2c and v3 user names and the groups they belong to.
• vacmAccessTable — the table contains a list of SNMP contexts to groups mappings and, respectively, the names of the SNMP views under those contexts, to which users in the group are granted read-only, read-write access or receive notifications for the objects under the subtree in the relevant view.
• vacmViewTreeFamilyTable — the table contains a list of SNMP views, i.e. entries specifying the OID of a MIB subtree and whether access to the objects under this subtree is to be allowed or forbidden.

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📁 FILES 📁

• /usr/share/snmp/defs/vacm_tree.def — the description of the MIB tree implemented by snmp_vacm.

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👀 SEE ALSO 👀

bsnmpd(1), gensnmptree(1), snmpmod(3)

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📜 STANDARDS 📜

IETF RFC 3415

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👑 AUTHORS 👑

Shteryana Shopova <syrinx@FreeBSD.org>

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xoxo, your fave manual page 💅 — this one is Debian, dated October 7, 2010, and it's the page for SNMP_VACM(3). 🫶