djsincla / mini-snmpd

A minimal SNMP agent implementation

Mini SNMP Daemon

The Mini SNMP daemon is a minimal implementation of an SNMP daemon. It is primarily targeted at embedded systems with limited disk and memory resources. All configuration can be done using command line arguments, but it also supports a minimal .conf file. It supports basic CPU, memory, disk, and network interface statistics.

mini-snmpd is not as flexibible as, and does not support the same features as, the de-facto standard net-snmp, but this also means it does not have the same footprint and overhead.

Supported features:

• SNMP version 1 and 2c (v3 is on the TODO list)
• Community string authentication when using 2c or explicitely configured
• Read-only access (writing is not supported)
• Includes basic system info like CPU load, memory, disk and network interfaces
• Does not need a configuation file
• Supports UDP and TCP (thus supports SSH tunneling of SNMP connections)
• Supports linux kernel versions 2.4 and 2.6
• Supports FreeBSD (needs procfs mounted using "mount_linprocfs procfs /proc")

mini-snmpd has only been tested on x86 and ARM platforms using net-snmp as client, so big endian may not work.

• For info about licensing, see the file COPYING
• For info about using the program, see the file mini_snmpd.8
• For info about how to (cross)compile the program, see the file Makefile
• For info about how to extend the MIB, see the file README.develop

Examples

Start the daemon:

./mini_snmpd -n -p 16161 -D "My laptop" -L "Batcave" \
             -C "Ops <[e-mail]>" -d '/' -i wlp3s0

Check uptime, useful to "ping" a device over SNMP:

snmpget -c public -v2c 127.0.0.1:16161 system.sysUpTime.0
DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (93103) 0:15:31.03

Complete walk:

snmpwalk -v2c -c public 127.0.0.1:16161
SNMPv2-MIB::sysDescr.0 = STRING: My laptop
SNMPv2-MIB::sysObjectID.0 = OID: SNMPv2-SMI::enterprises
DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (93103) 0:15:31.03
SNMPv2-MIB::sysContact.0 = STRING: Ops <[e-mail]>
SNMPv2-MIB::sysName.0 = STRING: luthien
SNMPv2-MIB::sysLocation.0 = STRING: Batcave
IF-MIB::ifNumber.0 = INTEGER: 1
IF-MIB::ifIndex.1 = INTEGER: 1
IF-MIB::ifDescr.1 = STRING: wlp3s0
IF-MIB::ifType.1 = INTEGER: ethernetCsmacd(6)
IF-MIB::ifMtu.1 = INTEGER: 1500
IF-MIB::ifSpeed.1 = Gauge32: 1000000000
IF-MIB::ifPhysAddress.1 = STRING: 6c:88:14:48:57:1c
IF-MIB::ifAdminStatus.1 = INTEGER: up(1)
IF-MIB::ifOperStatus.1 = INTEGER: up(1)
IF-MIB::ifLastChange.1 = Timeticks: (0) 0:00:00.00
IF-MIB::ifInOctets.1 = Counter32: 207845364
IF-MIB::ifInUcastPkts.1 = Counter32: 154221
IF-MIB::ifInDiscards.1 = Counter32: 0
IF-MIB::ifInErrors.1 = Counter32: 0
IF-MIB::ifOutOctets.1 = Counter32: 13323787
IF-MIB::ifOutUcastPkts.1 = Counter32: 88071
IF-MIB::ifOutDiscards.1 = Counter32: 0
IF-MIB::ifOutErrors.1 = Counter32: 0
HOST-RESOURCES-MIB::hrSystemUptime.0 = Timeticks: (454155) 1:15:41.55

Check load average:

snmpwalk -v2c -c public 127.0.0.1:16161 UCD-SNMP-MIB::laLoad
UCD-SNMP-MIB::laLoad.1 = STRING: 0.56
UCD-SNMP-MIB::laLoad.2 = STRING: 0.46
UCD-SNMP-MIB::laLoad.3 = STRING: 0.36

Check monitored disks:

snmpwalk -v2c -c public 127.0.0.1:16161 UCD-SNMP-MIB::dskTable
UCD-SNMP-MIB::dskIndex.1 = INTEGER: 1
UCD-SNMP-MIB::dskPath.1 = STRING: /
UCD-SNMP-MIB::dskTotal.1 = INTEGER: 245084448
UCD-SNMP-MIB::dskAvail.1 = INTEGER: 38953552
UCD-SNMP-MIB::dskUsed.1 = INTEGER: 206130896
UCD-SNMP-MIB::dskPercent.1 = INTEGER: 85
UCD-SNMP-MIB::dskPercentNode.1 = INTEGER: 10

Build & Install

The [GNU Configure & Build][buildsystem] system use /usr/local as the default install prefix. Usually this is sufficient, the below example installs to /usr instead:

tar xf mini-snmpd-1.4.tar.xz
cd mini-snmpd-1.4/
./configure --prefix=/usr
make -j5
sudo make install-strip

Building from GIT

If you want to contribute, or simply want to try out the latest but still unreleased features, then you need to know a few things about the [GNU Configure & Build][buildsystem] system:

• configure.ac and a per-directory Makefile.am are key files
• configure and Makefile.in are generated from autogen.sh, they are not stored in GIT but automatically generated for the release tarballs
• Makefile is generated by configure script

To build from GIT you first need to clone the repository and run the autogen.sh script. This requires automake and autoconf to be installed on your system.

git clone https://github.com/troglobit/mini-snmpd.git
cd mini-snmpd/
./autogen.sh
./configure && make

GIT sources are a moving target and are not recommended for production systems, unless you know what you are doing!

Origin & References

mini-snmpd on is an effort by Joachim Nilsson to create a focal point for patches and development of the original mini_snmpd project by Robert Ernst, since the original site now has gone dark.

The new project is maintained at GitHub. Use its issue tracker and pull request functions to report bugs or contribute new features.