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Snmp example on linux

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Содержание
  1. Linux SNMP: Simple Network Management Protocol:
  2. Installation:
  3. Configure:
  4. Start:
  5. Test:
  6. Installation:
  7. How To Install and Use SNMP On Linux Tutorial with Examples?
  8. What Is SNMP?
  9. Install SNMP Packages
  10. Fedora, CentOS, RedHat
  11. Ubuntu, Debian, Mint, Kali
  12. Start SNMP Service
  13. Check SNMP Service
  14. SNMP Configuration File
  15. Change Public Community String
  16. Restart SNMP Service and Reload Configuration
  17. Get and Display SNMP Attributes/Values with snmpwalk
  18. How To Install and Use SNMP On Linux Tutorial with Examples? Infographic

Linux SNMP: Simple Network Management Protocol:

SNMP or Simple Network Management Protocol, is a technology standard for alert messages (trap), monitoring (get), and configuring (set) network devices. SNMP comes in three varieties: v1, v2 and v3, of which v3 is the only version to be considered secure.

The variables associated with a network device configuration is defined in the Management Information Base, or MIB. The MIB is a collection of information for managing the network element and is comprised of managed objects identified by the Object Identifier (OID). Each OID is unique and identifies a special characteristic of the managed network device. SNMP is built upon a client (SNMP manager) — server (SNMP agent/network device) architecture pattern with a message schema defined by the MIB and sent over UDP port 161 (SNMP agent) and port 162 (SNMP manager). Each of the data values defined by the MIB are associated with an OID identified by a hierarchy of numbers separated by periods.

Installation:

  • CentOS/RedHat: sudo yum install net-snmp-utils net-snmp net-snmp-devel
    (RPMs also included with CentOS/RHEL 6 and 7 install DVDs)
  • Ubuntu: sudo apt-get install snmp snmpd snmp-mibs-downloader

Configure:

  • System file /etc/snmp/snmpd.conf
    This file default restricts access to localhost only.
  • User file ~/.snmp/snmp.conf

Start:

  • CentOS/RedHat:
    • sudo systemctl enable snmpd.service
    • sudo systemctl start snmpd.service
    • sudo systemctl status snmpd.service
    snmpd.service - Simple Network Management Protocol (SNMP) Daemon. Loaded: loaded (/usr/lib/systemd/system/snmpd.service; enabled; vendor preset: disabled) Active: active (running) since Tue 2019-07-02 17:03:02 PDT; 3s ago Main PID: 345 (snmpd) Memory: 6.8M CGroup: /system.slice/snmpd.service └─345 /usr/sbin/snmpd -LS0-6d -f Jul 02 17:03:01 myhostname systemd[1]: Starting Simple Network Management Protocol (. Jul 02 17:03:02 myhostname snmpd[345]: NET-SNMP version 5.7.2 Jul 02 17:03:02 myhostname systemd[1]: Started Simple Network Management Protocol (S. Hint: Some lines were ellipsized, use -l to show in full.
    • sudo systemctl enable snmpd.service
    • sudo systemctl start snmpd.service
    • sudo systemctl status snmpd.service

    Test:

    • snmpwalk -v 1 localhost -c public .1.3.6.1
    • snmpwalk -v 1 localhost -c public system
    • Open firewall to everything (if using iptables): sudo iptables -F
      or
    • if using firewald: sudo firewall-cmd --permanent --new-service=snmp
      this command will add service to directory /etc/firewalld/services/
    snmp 161/tcp # Simple Net Mgmt Proto snmp 161/udp # Simple Net Mgmt Proto snmptrap 162/tcp # SNMPTRAP snmptrap 162/udp snmp-trap # Traps for SNMP cmip-man 163/tcp # ISO mgmt over IP (CMOT)

      RHEL 7: snmpget -v 1 -c public localhost sysDescr.0

    SNMPv2-MIB::sysDescr.0 = STRING: Linux myhostname 3.10.0-693.el7.x86_64 #1 SMP Thu Jul 6 19:56:57 EDT 2017 x86_64
    iso.3.6.1.2.1.1.1.0 = STRING: "Linux myhostname 4.15.0-70-generic #79-Ubuntu SMP Tue Nov 12 10:36:11 UTC 2019 x86_64"
    +--iso(1) | +--org(3) | +--dod(6) | +--internet(1) | +--directory(1) | +--mgmt(2) | | | +--mib-2(1) | | | +--system(1) | | | | | +-- -R-- String sysDescr(1) | | | Textual Convention: DisplayString | | | Size: 0..255 | | +-- -R-- ObjID sysObjectID(2) | | +-- -R-- TimeTicks sysUpTime(3) | | | | | | | +--sysUpTimeInstance(0) | | | | | +-- -RW- String sysContact(4) | | | Textual Convention: DisplayString | | | Size: 0..255 . .
    :HOST-RESOURCES-MIB:HOST-RESOURCES-TYPES:UCD-DISKIO-MIB:TCP-MIB:UDP-MIB:MTA-MIB:NETWORK-SERVICES-MIB:SCTP-MIB:RMON-MIB:EtherLike-MIB:LM-SENSORS-MIB:SNMPv2-MIB:IF-MIB:IP-MIB:NOTIFICATION-LOG-MIB:DISMAN-EVENT-MIB:DISMAN-SCHEDULE-MIB:UCD-SNMP-MIB:UCD-DEMO-MIB:SNMP-TARGET-MIB:NET-SNMP-AGENT-MIB:SNMP-MPD-MIB:SNMP-USER-BASED-SM-MIB:SNMP-FRAMEWORK-MIB:SNMP-VIEW-BASED-ACM-MIB:SNMP-COMMUNITY-MIB:IPV6-ICMP-MIB:IPV6-MIB:IPV6-TCP-MIB:IPV6-UDP-MIB:IP-FORWARD-MIB:NET-SNMP-PASS-MIB:NET-SNMP-EXTEND-MIB:UCD-DLMOD-MIB:SNMP-NOTIFICATION-MIB:SNMPv2-TM:NET-SNMP-VACM-MIB /home/userx/.snmp/mibs:/usr/share/snmp/mibs
    iso.3.6.1.2.1.1.3.0 = Timeticks: (1310658) 3:38:26.58
    iso.3.6.1.4.1.2021.10.1.3.3 = STRING: "0.10"
    Command Description
    snmpcmd options and behavior common to most of the Net-SNMP command-line tools
    snmpwalk retrieve a subtree of management values using SNMP GETNEXT requests
    snmpget communicates with a network entity using SNMP GET requests
    snmpset communicates with a network entity using SNMP SET requests
    snmptrap sends an SNMP notification to a manager (also snmpinform)
    snmpgetnext communicates with a network entity using SNMP GETNEXT requests to get the next variable that is lexicographically «next» in the remote entity’s MIB
    snmptable retrieve an SNMP table and display it in tabular form
    snmpdelta Monitor delta differences in SNMP Counter values
    snmptest flexible SNMP application that can monitor and manage information on a network entity
    snmpdf display disk space usage on a network entity via SNMP
    snmpusm creates and maintains SNMPv3 users on a network entity
    snmpstatus retrieves a fixed set of management information from a network entity
    snmpnetstat display networking status and configuration information from a network entity via SNMP
    snmpbulkget SNMP application that uses the SNMP GETBULK request to query a network entity efficiently for information
    snmpbulkwalk retrieve a subtree of management values using SNMP GETBULK requests
    snmp.conf configuration files for the Net-SNMP applications
    SNMP Variables Format of specifying variable names to SNMP tools

    The Object Identifiers (OID)s are used to identify a specific characteristic of a managed device.

    1. Scalar: managed object with a single instance (a single key to a key-value pair)
    2. Tabular: multiple data instances such as the rows of a table (e.g. CPU with multiple cores each with its’ own specific charateristics)

    SNMP uses ASN.1 (Abstract Syntax Notation One) to define the data types used to build an SNMP message and uses Basic Encoding Rules (BER) to define the data types.

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