SNMP Labs SNMP Agent snmpd

1
SNMP LabsSNMP Agent - snmpd

• snmpd - listens to SNMP queries, answers them
• extensible agent
• a possibility to interface system functions to
  SNMPe.g. one can run system scripts or programs
  with snmpget
• possibility to monitor system functions that are
  not covered by MIBII by creation of a private MIB
• configuration of snmpd
• system information location, contact, name
• access control community name

2
SNMP LabsInstallation of CMUSNMP package

• ftp sun-ultra
  get UCD package user snmp passwd
  snmpbinget ucd_snmp.tar
• tar -xvf ucd-snmp.tar
  untar it
• cd ucd-snmp-3.5.xx
• more INSTALL it
  is good to read documentation
• ./configure
• Answer questionssystem contact,
  location
• make
• su -
  become root
• make install

3
SNMP LabsBasic configuration of snmpd

• ftp sun-ultra
  get snmpd.conf file user snmp passwd
  snmpasciiget snmpd.conf
• pico snmpd.conf
• Set syslocation syscontact
• cp snmpd.conf /usr/local/share/snmp/snmpd.conf
• snmpd
  run snmpd

4
SNMP LabsBasic commands snmpwalk, snmpget,
snmpnetstat

• man snmpwalk
  read documentation..
• snmpwalk qqqq public more qqqq is a
  name of your neighbours station
• man snmpget
• snmpget .. do
  it yourself..
• snmpnetstat
  do it yourself

5
SNMPGetting information with snmpget, snmpwalk

• To see what-s available on local Linux station
• snmpwalk localhost public more
• (will show all MIB variables supported by snmpd
  public is a community name)
• To see a single variable or a set of variables
• snmpget host_name community_name
  object_identifier
• To see all variables down in the OID tree from a
  variable variable
• snmpwalk host_name community_name variable
• (without variable the whole MIB is shown)

6
SNMPHow to address MIB entities

• OID can be given in numerical or mnemonic form
• It can be given starting from the Internet leaf,
  e.g.
• .1.3.6.1.2.1.0 (check meanings
  of all numbers, translate
  it into mnemonic form)
• ( . (dot)
  at the beginning is IMPORTANT)
• Or in a short form starting from the MIB-II leaf,
  e.g.
• 2.1.0 or
  interfaces.ifIndex.0
• Translation between numerical and mnemonic form
  can be done e.g. by tkined (tkined - Tools -
  SNMP tree - click on an entity describe see
  further labs), or using lecture handouts (a
  painful way)

7
SNMPHow to address MIB entities?

• OID
• scalar objects
• e.g. .1.3.6.1.2.1.0 - 0 is also
  important, it denotes an object instance
• tables
• e.g. .1.3.6.1.2.2.1.2.2 - rightmost 2 is
  a row index in a table of interfaces table
  indexes generally start at 1 !!

8
SNMPexercises - snmpwalk, snmpget

• Using snmpwalk see descriptions of interfaces of
  your workstation (OID of interfaces.ifTable.ifEntr
  y.ifDescr is 2.2.1.2)
• Using only snmpwalk and snmpget find the MAC
  address of Ethernet interface of your neighbours
  workstation
• Using snmpwalk and snmpget find the number of
  output octets on an Eth interface of a default
  router to which this LAN is connected check this
  number in approx. 1 minute interval - what is the
  minute average of a traffic on this interface?

9
SNMPexercises - snmpwalk, snmpget

• Also on Cisco - using snmpwalk and snmpget find
  to which Ethernet interface this LAN is connected
  (eth0 or eth1 or eth2 or )
• Try to run snmpwalk on some locations in your
  country are system contact and system location
  meaningful?

10
SNMP Labs MRTG - installation and introduction

• ftp sun-ultra
  get packages user snmp
  passwd snmp
• bin
• get gd1.3.tar
• get mrtg-2.5.3.tar
• quit
• tar -xvt gd1.3.tar
• tar -xvf mrtg-2.5.3.tar
• cd mrtg-2.5.3
• more INSTALL
  do what they say

11
SNMP Labs MRTG - installation and introduction

• Install GD library first - go to gd1.3 directory
• make
  just write make - it really works!!!
• cp libgd.a /usr/local/lib
• mkdir /usr/local/include/gd
• cp .h /usr/local/include/gd
• That is it..
• Go back to mrtg-2.5.3 directory
• Edit Makefile - correct a path to GD library and
  includes, correct a path to PERL - it should be
  /usr/bin/perl
• make rateup
• make substitute
• cp mrtg /usr/local/bin cp rateup /usr/local/bin
  cp .pm /usr/local/bin

12
SNMP Labs MRTG - installation and introduction

• cat WorkDir /usr/local/mrtg gt mrtg.conf
• cfgmaker public_at_qqq qqq is a name
  of your naighbours workstation
• read about preparing mrtg.conf in readme.html
• cfgmaker public_at_qqq gtgt mrtg.conf
• cp mrtg.conf /usr/local/mrtg
• Now you can run mrtg
• mrtg /usr/local/mrtg/mrtg.conf
• The results can be found in /usr/local/mrtg/qqq.h
  tml