SNMP Simple Simple Network Network Management Management Protocol

SNMP Simple Simple Network Network Management Management Protocol Protocol Chris Francois CS 417d Fall 1998 [email protected]

What What is is Network Network Management? Management? Basic tasks that fall under this category are: Configuration Management Keeping track of device settings and how they function Fault Management Dealing with problems and emergencies in the network (router stops routing, server loses power, etc.) Performance Management How smoothly is the network running? Can it handle the workload it currently has?

Network Network Management Management must must be. be. The management interface must be. Standardized Extendible Portable The management mechanism must be. Inexpensive Implemented as software only

Functional Functional Areas Areas of of Network Network Management Management Configuration Management - inventory, configuration, provisioning Fault Management - reactive and proactive network fault management Performance Management - # of packets dropped, timeouts, collisions, CRC errors Security Management - SNMP doesn’t provide much here Accounting Management - cost management and chargeback assessment Asset Management - statistics of equipment, facility, and administration personnel Planning Management - analysis of trends to help justify a network upgrade or bandwidth increase

SNMP SNMP && Network Network Management Management History History 1983 - TCP/IP replaces ARPANET at U.S. Dept. of Defense, effective birth of Internet First model for net management - HEMS - High-Level Entity Management System (RFCs 1021,1022,1024,1076) 1987 - ISO OSI proposes CMIP - Common Management Information Protocol, and CMOT (CMIP over TCP) for the actual network management protocol for use on the internet Nov. 1987 - SGMP - Simple Gateway Monitoring protocol (RFC 1028) 1989 - Marshall T. Rose heads up SNMP working group to create a common network management framework to be used by both SGMP and CMOT to allow for transition to CMOT Aug. 1989 - “Internet-standard Network Management Framework” defined (RFCs 1065, 1066, 1067) Apr. 1989 - SNMP promoted to recommended status as the de facto TCP/IP network management framework (RFC 1098) June 1989 - IAB committee decides to let SNMP and CMOT develop separately May 1990 - IAB promotes SNMP to a standard protocol with a recommended status (RFC 1157) Mar. 1991 - format of MIBs and traps defined (RFCs 1212, 1215) TCP/IP MIB definition revised to create SNMPv1 (RFC 1213)

Versions Versions Two major versions SNMPv1, SNMPv2 SNMPv1 is the recommended standard SNMPv2 has become split into: SNMPv2u - SNMPv2 with user-based security SNMPv2* - SNMPv2 with user-based security and additional features SNMPv2c - SNMPv2 without security

What What is is SNMP? SNMP? 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 Agent - process running on each managed node collecting information about the device it is running on. Manager - process running on a management workstation that requests information about devices on the network.

Advantages Advantages of of using using SNMP SNMP Standardized universally supported extendible portable allows distributed management access lightweight protocol

Client Client Pull Pull & & Server Server Push Push 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

SNMP SNMP & & The The OSI OSI Model Model 7 Application Layer Management and Agent APIs SNMP 6 Presentation Layer ASN.1 and BER 5 Session Layer RPC and NetBIOS 4 Transport Layer TCP and UDP 3 Network Layer IP and IPX 2 Data Link Layer Ethernet, Token Ring, FDDI 1 Physical Layer

Ports Ports & & UDP UDP SNMP uses User Datagram Protocol (UDP) as the transport mechanism for SNMP messages Ethernet Frame IP Packet UDP Datagram SNMP Message CRC Like FTP, SNMP uses two well-known ports to operate: UDP Port 161 - SNMP Messages UDP Port 162 - SNMP Trap Messages

The The Three Three Parts Parts of of SNMP SNMP SNMP network management is based on three parts: SNMP Protocol Defines format of messages exchanged by management systems and agents. Specifies the Get, GetNext, Set, and Trap operations Structure of Management Information (SMI) Rules specifying the format used to define objects managed on the network that the SNMP protocol accesses Management Information Base (MIB) A map of the hierarchical order of all managed objects and how they are accessed

Nodes Nodes Items in an SNMP Network are called nodes. There are different types of nodes. Managed nodes Typically runs an agent process that services requests from a management node Management nodes Typically a workstation running some network management & monitoring software Nodes that are not manageable by SNMP A node may not support SNMP, but may be manageable by SNMP through a proxy agent running on another machine Nodes can be both managed nodes and a management node at the same time (typically this is the case, since you want to be able to manage the workstation that your management application is running on.)

Community Community Names Names Community names are used to define where an SNMP message is destined for. They mirror the same concept as a Windows NT or Unix domain. Set up your agents to belong to certain communities. Set up your management applications to monitor and receive traps from certain community names.

SNMP SNMP Agents Agents Two basic designs of agents Extendible Agents Open, modular design allows for adaptations to new management data and operational requirements Monolithic Agents not extendible optimized for specific hardware platform and OS this optimization results in less overhead (memory and system resources) and quicker execution

Proxy Proxy & & Gateway Gateway Agents Agents Proxy & Gateway Agents extend the capabilities of SNMP by allowing it to: Manage a device that cannot support an SNMP agent Manage a device that supports a non-SNMP management agent Allow a non-SNMP management system to access an SNMP agent Provide firewall-type security to other SNMP agents (UDP packet filtering) Translate between different formats of SNMP messages (v1 and v2) Consolidate multiple managed nodes into a single network address (also to provide a single trap destination)

Four Four Basic Basic Operations Operations Get Retrieves the value of a MIB variable stored on the agent machine (integer, string, or address of another MIB variable) GetNext Retrieves the next value of the next lexical MIB variable Set Changes the value of a MIB variable Trap An unsolicited notification sent by an agent to a management application (typically a notification of something unexpected, like an error)

Traps Traps Traps are unrequested event reports that are sent to a management system by an SNMP agent process When a trappable event occurs, a trap message is generated by the agent and is sent to a trap destination (a specific, configured network address) Many events can be configured to signal a trap, like a network cable fault, failing NIC or Hard Drive, a “General Protection Fault”, or a power supply failure Traps can also be throttled -- You can limit the number of traps sent per second from the agent Traps have a priority associated with them -- Critical, Major, Minor, Warning, Marginal, Informational, Normal, Unknown

Trap Trap Receivers Receivers Traps are received by a management application. Management applications can handle the trap in a few ways: Poll the agent that sent the trap for more information about the event, and the status of the rest of the machine. Log the reception of the trap. Completely ignore the trap. Management applications can be set up to send off an e-mail, call a voice mail and leave a message, or send an alphanumeric page to the network administrator’s pager that says: ur PDC just Blue-Screened at 03:46AM. Have a nice day.

Languages Languages of of SNMP SNMP Structure of Management Information (SMI) specifies the format used for defining managed objects that are accessed via the SNMP protocol Abstract Syntax Notation One (ASN.1) used to define the format of SNMP messages and managed objects (MIB modules) using an unambiguous data description format Basic Encoding Rules (BER) used to encode the SNMP messages into a format suitable for transmission across a network

SMIv1 SMIv1 Structure of Management Information SMIv1 is described in RFCs 1155, 1212, 1215 These RFCs describe: How MIB modules are defined with CCITT X.208 ASN.1 data description language The subset of the ASN.1 language that is used in MIBs The addition of the APPLICATION data type to ASN.1, specifically for use with SNMP MIBs All ASN.1 constructs are serialized using the CCITT X.209 BER for transmission across the wire definition of the high-level structure of the Internet branch (iso(1).org(3).dod(6).internet(1)) of the MIB naming tree the definition and description of an SNMP managed object

SMIv2 SMIv2 Structure of Management Information SMIv2 is described in RFCs 1442, 1443, 1444 These RFCs describe: SMIv2 is a backward compatible update to SMIv1 The only exception is the Counter64 type defined by SMIv2 Counter64 cannot be created in SMIv2 RFC 2089 defines how bilingual (SMIv1 & SMIv2) agents handle the Counter64 data type IETF requires that new and revised RFCs specify MIB modules using SMIv2

ASN.1 ASN.1 Abstract Syntax Notation One ASN.1 is nothing more than a language definition. It is similar to C/C and other programming languages. Syntax examples: -- two dashes is a comment -- The C equivalent is written in the comment MostSevereAlarm :: INTEGER -- typedef MostSevereAlarm int; circuitAlarms MostSevereAlarm :: 3 -- MostSevereAlarm circuitAlarms 3; MostSevereAlarm :: INTEGER (1.5) -- specify a valid range ErrorCounts :: SEQUENCE { circuitID OCTET STRING, erroredSeconds INTEGER, unavailableSeconds INTEGER } -- data structures are defined using the SEQUENCE keyword

BER BER Basic Encoding Rules The relationship between ASN.1 and BER parallels that of source code and machine code. CCITT X.209 specifies the Basic Encoding Rules All SNMP messages are converted / serialized from ASN.1 notation into smaller, binary data (BER)

SNMP SNMP Data Data Types Types INTEGER -- signed 32-bit integer Yellow items defined by ASN.1 OCTET STRING Orange items defined OBJECT IDENTIFIER (OID) by RFC 1155 NULL -- not actually data type, but data value IpAddress -- OCTET STRING of size 4, in network byte order (B.E.) Counter -- unsigned 32-bit integer (rolls over) Gauge -- unsigned 32-bit integer (will top out and stay there) TimeTicks -- unsigned 32-bit integer (rolls over after 497 days) Opaque -- used to create new data types not in SNMPv1 DateAndTime, DisplayString, MacAddress, PhysAddress, TimeInterval, TimeStamp, TruthValue, VariablePointer -- textual conventions used as types

Managed Managed “Objects” “Objects” & & MIBs MIBs Always defined and referenced within the context of a MIB A typical MIB variable definition: sysContact OBJECT-TYPE -- OBJECT-TYPE is a macro SYNTAX DisplayString (SIZE (0.255)) ACCESS read-write -- or read-write, write-only, not-accessible STATUS mandatory -- or optional, deprecated, obsolete DESCRIPTION “Chris Francois [email protected] (360)650-0000” :: { system 4 }

Basic Basic Message Message Format Format Message Length Message Version Community String Message Preamble PDU Header PDU Body SNMP Protocol Data Unit

SNMP SNMPMessage MessageFormats Formats Message Length Message Version SNMP Message Preamble Community String PDU Type PDU Length Request ID Error Status Error Index PDU Header Message Length Message Version Community String PDU Type PDU Length Enterprises MIB OID Agent IP Address Standard Trap Type Specific Trap Type Time Stamp Length of Variable Bindings Length of Variable Bindings Length of First Binding Length of First Binding OID of First Binding Type of First Binding OID of First Binding Type of First Binding Value of First Binding Length of Second Binding PDU Body Value of First Binding OID of Second Binding Type of Second Binding Length of Second Binding OID of Second Binding Type of Second Binding Value of Second Binding Value of Second Binding Additional Variable Bindings Additional Variable Bindings

Commercial Commercial SNMP SNMP Applications Applications Here are some of the various SNMP Management products available today: http://www.hp.com/go/openview/ HP OpenView http://www.tivoli.com/ IBM NetView http://www.novell.com/products/managewise/ Novell ManageWise http://www.sun.com/solstice/ Sun MicroSystems Solstice http://www.microsoft.com/smsmgmt/ Microsoft SMS Server http://www.compaq.com/products/servers/management/ Compaq Insight Manger http://www.redpt.com/ SnmpQL - ODBC Compliant http://www.empiretech.com/ Empire Technologies ftp://ftp.cinco.com/users/cinco/demo/ Cinco Networks NetXray http://www.netinst.com/html/snmp.html SNMP Collector (Win9X/NT) http://www.netinst.com/html/Observer.html Observer http://www.gordian.com/products technologies/snmp.html Gordian’s SNMP Agent http://www.castlerock.com/ Castle Rock Computing http://www.adventnet.com/ Advent Network Management http://www.smplsft.com/ SimpleAgent, SimpleTester

SNMP SNMP & & Windows Windows NT NT 5.0 5.0 Proposed features of the Windows NT5 SNMP Service Full bilingual support for SNMPv1 and SNMPv2c ability to map SNMPv2c requests to SNMPv1 for processing by extension agents better synchronization of MIB variables a new extension agent framework (backward compatible with original framework, but with MS add-ons) code-generator for creation of extension agents MIB-II, LAN Manager 2, IP Forwarding MIB (RFC 1354), and Host Resources MIB (RFC 1514) extension agents included All MIB modules included with SNMP install SMS 2.0 also has a Symantec PCAnywhere type of application integrated into it, allowing “remote-but-local” management as well

RFC Description SNMP SNMP RFC’s RFC’s 1065 1066 1067 1098 1155 1156 1157 1158 1212 1213 1215 1351 1352 1353 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 SMIv1 SNMPv1 MIB SNMPv1 SNMPv1 SMIv1 SNMPv1 MIB SNMPv1 SNMPv1 MIB-II SNMPv1 MIB definitions SNMPv1 MIB-II SNMPv1 traps Secure SNMP administrative model Secure SNMP managed objects Secure SNMP security protocols Introduction to SNMPv2 SMIv2 Textual conventions for SNMPv2 Conformance statements for SNMPv2 SNMPv2 administrative model SNMPv2 security protocols SNMPv2 party MIB SNMPv2 protocol operations SNMPv2 transport mapping SNMPv2 MIB Manger-to-manger MIB Coexistence of SNMPv1 and SNMPv2 Community-Based SNMPv2 SMIv2 Textual conventions for SNMPv2 Conformance statements for SNMPv2 Protocol operations for SNMPv2 Transport mapping for SNMPv2 SNMPv2 MIB Coexistence of SNMPv1 and SNMPv2 Administrative infrastructure for SNMPv2 User-based security for SNMPv2 Published Current Status Aug-88 Aug-88 Aug-88 Apr-89 May-90 May-90 May-90 May-90 Mar-91 Mar-91 Mar-91 Jul-92 Jul-92 Jul-92 Apr-93 Apr-93 Apr-93 Apr-93 Apr-93 Apr-93 Apr-93 Apr-93 Apr-93 Apr-93 Apr-93 Apr-93 Jan-96 Jan-96 Jan-96 Jan-96 Jan-96 Jan-96 Jan-96 Jan-96 Feb-96 Feb-96 Obsoleted by 1155 Obsoleted by 1156 Obsoleted by 1098 Obsoleted by 1157 Standard Historic Standard Obsoleted by 1213 Standard Standard Informational Proposed Standard Proposed Standard Proposed Standard Proposed Standard Obsoleted by 1902 Obsoleted by 1903 Obsoleted by 1904 Historic Historic Historic Obsoleted by 1905 Obsoleted by 1906 Obsoleted by 1907 Historic Obsoleted by 1908 Experimental Draft Standard Draft Standard Draft Standard Draft Standard Draft Standard Draft Standard Draft Standard Experimental Experimental