1. Test Case Generation for testing SNMP agents
Diana Serbanescu (Fraunhofer FOKUS) & Theofanis Vassiliou-Gioles (Testing Technologies)

2. diana.serbanescu@ fokus.fraunhofer.de
Contact
Diana Serbanescu
Fraunhofer FOKUS
fokus.fraunhofer.de
Theo Vassiliou
Testing Technologies

3. Agenda
Why SNMP?
An Introduction to SNMP
Technical Solution

4. Why bother for SNMP at all?
First version has been defined in the late 1980s
RFC 1067, 1098, 1157
A protocol to monitor and manage network elements
Defines a message structure and communication flows
Widely deployed and heavily used in the IT datacom industry
Router, switches, servers, network printers, ...
One would think that SNMP is
Well established
Well deployed and there
Well tested!

5. New Domains – New Applications

6. Summary – Why SNMP SNMP is well established in the IT community
Application to new domains require thorough testing
of existing functionality
in sometimes hazard environments
by not native IT/datacom experts

7. Introduction to SNMP (I)
SNMP is a tool (protocol) that allows for remote and local management of items on the network including servers, workstations, routers, switches and other managed devices
Comprised of
agents and
managers
SNMP is a “client pull” model
The management system (client) “pulls” data from the agent (server)
SNMP is a “server push” model
The agent (server) “pushes” out a trap message to a (client) management system

8. Introduction to SNMP (II)
SNMP management
SNMP Protocol
Definition of message format
Operation specification
Structure of Management Information (SMI)
Rules specifying the format used to define objects managed
Management Information Base (MIB)
A map all managed objects
Languages of SNMP
ASN.1
Used to define the MIBs
Basic Encoding Rules (BER)
For SNMP message encoding
Three different versions of SNMP defined over the years
v1, v2 and v3
V3 adds authorization and encryption

9. MIBs : Management Information Base MIB-I9

10. The Object Identifier (OID)
A scheme that allows two vendors or products within a vendor to compare like items
Object identifiers (OID) as the identification scheme
An OID is an ordered sequence of non-negative integers written left to right, containing at least two elements
Once a MIB module is published, OIDs are bound for all time to the objects defined
Objects cannot be deleted
Can only be made obsolete
Even minor changes to an object are discouraged 10

11. SNMP Operations (v1, v2 & v3)
Get
Get-next
Get-bulk (SNMPv2 and SNMPv3)
Set
Get-response
Trap
Inform (SNMPv2 and SNMPv3)
Report (SNMP2 and SNMPv3) 11

12. SNMP PDU Sequences Manager Agent GetNextRequest PDU GetRequest PDU
GetResponse PDU
SetRequest PDU
GetNextRequest PDU
Trap PDU
(a) Get values
(b) Get next values
(c) Set values
(d) Send trap 12

13. SNMP Security Mechanisms - Summary13

14. Summary – What is SNMP? A protocol to manage network agents
Communication is ASN.1/BER based
MIBs define the managed objects
Different versions of SNMP are available
Security plays a major role in v3 but it is considered difficult to handle by users.

15. Test Aspects
Single and multiple (table) values for the objects defined in the given MIB file(s) should be verified for type and value conformance
Test the main operations for each version of the SNMP protocol that is being used
GET/GET-NEXT/GET-BULK/SET
Negative and positive tests
Positive: e.g. GET a read-write object
Negative: e.g. SET a read-only object
Test the main operations within different security levels 15

16. Abstract Test Architecture for SNMP
SNMPv3 Testing: Basic Test Concept Configuration
TTCN-3
Test System
Convert MIB definitions to TTCN-3
and import them in TTCN-3 modules
Act as a SMP Manager
SNMP Transmission
SNMP Entity
Compile MIB definitions
MIB document
SNMP Agent
SUT 16

17. Abstract Architecture for Testing SNMP jointly with other Protocols/Test Access
SNMP TTCN-3 Test System
SUT
SET (USM)
SNMP Testing Module
SNMP
GET / GETNEXT GET BULK
GET RESPONSE / TRAP
Generic Test Access IP
LPT
WebService 17

18. Abstract Workflow Create the test components
Process MIBs
Create the test components
Create a TTCN-3 type system for messages
Create test case templates
Create test cases to test generic SNMP compliance
Per defined OID create the relevant test templates
Adapt the templates
Use additional test access to enforce predictable SNMP values
Execute the generated tests

19. TTplugin-SNMP Generated Artefacts
Pattern 1
Pattern 2
Pattern 3
Pattern 4
Pattern 5
Pattern 6
Pattern 7
MIB
Test Cases
Type System
SUT

20. The Patterns Testing for type conformance Testing for values
T5, T6, T7
Testing for access rights
T2, T4
Testing for values can be enhanced by value enforcement via additional test access
Web Service, IP Packets,

21. The Complete Test System
Test Cases
Type System
TTworkbench
Codec
Port
External
Functions
SUT

22. Summary & Outlook Summary Outlook
A test architecture as TTplugin-SNMP for testing SNMPv1,2,3 was developed
Focus was on the seamless management of the different SNMP version and security mechanisms
Test case templates that cover the main groups of tests for SNMP are defined and implemented in the framework
A very powerful framework to quickly define test cases to SNMP agents and/or SNMP masters
TTplugin –SNMP can also be used to manipulate SNMP manged system in non-SNMP testing context
Outlook
To generate more test cases based on generic patterns 22

23. Further information Fraunhofer FOKUS – MOTION Testing Technologies
Testing Technologies
testingtech.com
facebook.com -> Testing-Technologies
TTplugin-SNMP
testingtech.com/products/ttplugins_snmp.php
testingtech.com/download/datasheets/PlugSNMP.pdf