email or call for office visit, or call Kathy Cheek, 404 894-5696 ECE-6612 http://www.csc.gatech.edu/copeland/jac/6612/ Prof. John A. Copeland john.copeland@ece.gatech.edu 404 894-5177 fax 404 894-0035 Office: Centergy 5138, VL w315 email or call for office visit, or call Kathy Cheek, 404 894-5696 Chap 8: SNMP - Simple Network Mgmt Protocol Includes copies of figures from Chap. 8 of “Network Security Essentials, Applications and Standards” by William Stallings

Network Management Architecture An integrated collection of tools for network monitoring and control. • Single operator interface. • Minimal amount of separate equipment – software and network communications capability built into the existingequipment. The primary parts are: • Management station (central control, has a “agent”) • Management agents (software in network equipment) • Management Information Base (MIB) • Network management protocol (rules for communication) 2

3

“SNMP Agents” located on the controlled network systems. SNMP Terminology “SNMP Management Station” - central control. It can set parameters and collect information from the “SNMP Agents” located on the controlled network systems. “Proxy” – an add-on box to add SNMP features to a network unit (router, modem, PC, …) that does not have built-in SNMP capability. “Trap” – an unsolicited message, perhaps reporting an alarm condition (to UDP port 162). “Intermediate Management Station” - for distributed control. It can set parameters and collect information from the Agents on a local region of the network. Only the more important information would be passed up to the Management Station. 4

Problems with SNMP v1 addressed by version 2: SNMP v1, v2, and v3 SNMPv1 (version 1) is “connectionless” since it utilizes UDP (rather than TCP) as the transport layer protocol. SNMPv2 allows the use of TCP for “reliable, connection-oriented” service. Problems with SNMP v1 addressed by version 2: • Lack of support for distributed network management. • Functional deficiencies - v2 can use TCP/IP and Novell IPX Problem addressed by version 3: • Security - version 1 used a community name as a password. • Version 3 adds encryption, and host authentication, 5

The Role of SNMP 6

Proxy Configuration 7

SNMP v3 – a Security Add-on SNMP v3 “engine” operating at the Application Layer: • On outgoing PDU’s inserts authentication codes (MACs), encrypts certain fields, encapsulates the PDU into a message for transmission. • For incoming messages (from the Transport Layer) performs authentication verification, decryption, and extracts PDU’s from the message to pass up to the SNMP applications above. • Security Subsystem- performs the authentication and encryption tasks. 8

SNMP Protocol Architecture 9

SNMPv3 PDU with User Security Model (USM) 10

Messages Use the Management Info. Base (MIB) and ASN.1 (Abstract Syntax Notation) Objects (Parameters ) are expressed as leaves on the MIB tree. Object Object ID (OID) +--iso(1) .1 +--org(3) .1.3 +--dod(6) .1.3.6 +--internet(1) .1.3.6.1 +--directory(1) .1.3.6.1.1 +--mgmt(2) .1.3.6.1.2 | +--mib-2(1) .1.3.6.1.2.1 | +--transmission(10) .1.3.6.1.2.10 +--experimental(3) .1.3.6.1.3 +--private(4) .1.3.6.1.4 | +--enterprises(1) .1.3.6.1.4.1 [next number is company ID]* +--security(5) .1.3.6.1.5 +--snmpV2(6) .1.3.6.1.6 +--snmpDomains(1) .1.3.6.1.6.1 +--snmpProxys(2) .1.3.6.1.6.2 +--snmpModules(3) .1.3.6.1.6.3 * when a company gets a number from IANA, it can extend the tree to cover a new system. 11

Decoding a UDP Trap Message trap_server.pl 9/26/04 22:45 [data has the form: 30(length), (6)OID, (42) value or (44) string] From: 209.128.181.100 Mon Sep 27 21:24:26 EDT 2004 Len: 82 1 26 - 294 Version: 2 Domain: public Reg_ID: 391 Error: 0 Index: 0 Byte: 29 Type: 30 0 82 1 9 - 265 Byte: 33 Type: 30 1 f - 15 Byte: 35 Type: 6 1 .1.3.6.1.2.1.1.3.0 System Up Time (0.01 s) Byte: 45 Type: 43 1 1977555 -> sysUpTime = 19775.55 s Byte: 50 Type: 30 1 1c - 28 Byte: 52 Type: 6 2 .1.3.6.1.6.3.1.1.4.1.0 Type of Event Byte: 64 Type: 6 2 .1.3.6.1.4.1.8712.4.1.1.2.1.7.5 Indicates that the IP has a profile violation. -> snmpTrapOID = swCoreEventOOP Byte: 80 Type: 30 2 2a - 42 Byte: 82 Type: 6 3 .1.3.6.1.4.1.8712.4.1.1.2.1.1.1 Byte: 98 Type: 44 3 StealthWatch+Therminator -> stealthwatchCoreConfig = StealthWatch+Therminator Byte: 124 Type: 30 3 16 - 22 Byte: 126 Type: 6 4 .1.3.6.1.4.1.8712.4.1.1.2.1.6.1.1 The unique alarm identifier (serial no). Byte: 143 Type: 42 4 207986 -> stealthwatchCoreAlarmsId = 207986 Byte: 148 Type: 30 4 22 - 34 Byte: 150 Type: 6 5 .1.3.6.1.4.1.8712.4.1.1.2.1.6.1.3 Host Ip Address of [that caused] the alarm. Byte: 167 Type: 44 5 209.182.185.012 -> stealthwatchCoreAlarmsHost = 209.182.185.012 12

Sources of Information on the Web To work with SNMP messages on a unix system, install the Net-SNMP utilitys, available at “www.net-snmp.org” A number of standard MIBs will then be found in /usr/share/snmp/mibs To look up Enterprise Numbers, go to Web site of the Internet Assigned Numbers Authority (IANA), “www.iana.org/assignments/enterprise-numbers”. The “List of Lists” at “www.iana.org/numbers.html” is a wonderful body of information on all the Internet assigned numbers (protocols, ports, IPs vs. area, AS numbers, ...). For information on ASN.1 - “www.cs.columbia.edu/~hgs/internet/asn.1.html” RFC’s on SNMP: 788, 1098, 1215, 1442, 1592, 1906, 2578. To get them, use “www.ietf.org/rfc/rfc<number_here>.txt” 13