From owner-freebsd-net@freebsd.org  Tue Feb 20 17:50:35 2018
Return-Path: <owner-freebsd-net@freebsd.org>
Delivered-To: freebsd-net@mailman.ysv.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1])
 by mailman.ysv.freebsd.org (Postfix) with ESMTP id 4A51AF192C3
 for <freebsd-net@mailman.ysv.freebsd.org>;
 Tue, 20 Feb 2018 17:50:35 +0000 (UTC)
 (envelope-from eugen@grosbein.net)
Received: from hz.grosbein.net (hz.grosbein.net [78.47.246.247])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (Client CN "hz.grosbein.net", Issuer "hz.grosbein.net" (not verified))
 by mx1.freebsd.org (Postfix) with ESMTPS id C622A82C16
 for <freebsd-net@freebsd.org>; Tue, 20 Feb 2018 17:50:34 +0000 (UTC)
 (envelope-from eugen@grosbein.net)
Received: from eg.sd.rdtc.ru (root@eg.sd.rdtc.ru [62.231.161.221] (may be
 forged))
 by hz.grosbein.net (8.15.2/8.15.2) with ESMTPS id w1KHoMbn017695
 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT);
 Tue, 20 Feb 2018 18:50:23 +0100 (CET)
 (envelope-from eugen@grosbein.net)
X-Envelope-From: eugen@grosbein.net
X-Envelope-To: vas@mpeks.tomsk.su
Received: from [10.58.0.4] (dadv@[10.58.0.4])
 by eg.sd.rdtc.ru (8.15.2/8.15.2) with ESMTPS id w1KHoFJG012656
 (version=TLSv1.2 cipher=DHE-RSA-AES128-SHA bits=128 verify=NOT);
 Wed, 21 Feb 2018 00:50:15 +0700 (+07)
 (envelope-from eugen@grosbein.net)
Subject: Re: bsnmpd and arbitrary OIDs
To: Victor Sudakov <vas@mpeks.tomsk.su>, freebsd-net@freebsd.org
References: <20180220160044.GA79151@admin.sibptus.transneft.ru>
From: Eugene Grosbein <eugen@grosbein.net>
Message-ID: <5A8C5FD6.3070201@grosbein.net>
Date: Wed, 21 Feb 2018 00:50:14 +0700
User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:38.0) Gecko/20100101
 Thunderbird/38.7.2
MIME-Version: 1.0
In-Reply-To: <20180220160044.GA79151@admin.sibptus.transneft.ru>
Content-Type: text/plain; charset=windows-1252
Content-Transfer-Encoding: 8bit
X-Spam-Status: No, score=2.2 required=5.0 tests=BAYES_00, LOCAL_FROM, RDNS_NONE
 autolearn=no autolearn_force=no version=3.4.1
X-Spam-Report: * -2.3 BAYES_00 BODY: Bayes spam probability is 0 to 1%
 *      [score: 0.0000] *  2.6 LOCAL_FROM From my domains
 *  1.9 RDNS_NONE Delivered to internal network by a host with no rDNS
X-Spam-Level: **
X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on hz.grosbein.net
X-BeenThere: freebsd-net@freebsd.org
X-Mailman-Version: 2.1.25
Precedence: list
List-Id: Networking and TCP/IP with FreeBSD <freebsd-net.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/freebsd-net>,
 <mailto:freebsd-net-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-net/>
List-Post: <mailto:freebsd-net@freebsd.org>
List-Help: <mailto:freebsd-net-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/freebsd-net>,
 <mailto:freebsd-net-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 20 Feb 2018 17:50:35 -0000

20.02.2018 23:00, Victor Sudakov wrote:

> Is it possible to configure bsnmpd to return an arbitrary value for an OID, e.g.
> 
> snmpget -On -v1 -c public localhost .1.3.6.1.4.1.34498.2.1.1.1.2.0
> 
> should always return 
> 
> .1.3.6.1.4.1.34498.2.1.1.1.2.0 = STRING: "54.6 V"
> 
> I need this for debugging a network monitoring system.
> 
> Thank you very much in advance.

You can do that with net-mgmt/bsnmp-ucd addon and little addition to /etc/snmpd.config:

begemotSnmpdModulePath."ucd" = "/usr/local/lib/snmp_ucd.so"

%ucd
extNames.0 =    "kern.clockrate"
extCommand.0    = "/sbin/sysctl -n kern.clockrate"

Refer to bsnmp-ucd(8) manual page for defails.