snmp

nullSNMP Simple Network Management Protocol SNMP Simple Network Management Protocol Chris Francois CS 417d Fall 1998 cfrancois@acm.orgWhat is Network Management?Basic tasks that fall under this category are:What is Network Management?Network Management must be...Network Management must be... The management interface must be...The management mechanism must be...Standardized Extendible PortableInexpensive Implemented as software onlyFunctional Areas of Network ManagementFunctional Areas of Network 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 increaseSNMP & Network Management HistorySNMP & Network Management History1983 - 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)VersionsVersions 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 securityWhat is SNMP?What is 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 of using SNMPAdvantages of using SNMPStandardized universally supported extendible portable allows distributed management access lightweight protocolClient Pull & Server PushClient Pull & Server PushSNMP is a “client pull” modelSNMP is a “server push” modelThe management system (client) “pulls” data from the agent (server).The agent (server) “pushes” out a trap message to a (client) management systemSNMP & The OSI ModelSNMP & The OSI Model Ports & UDPPorts & UDP SNMP uses User Datagram Protocol (UDP) as the transport mechanism for SNMP messages UDP Port 161 - SNMP Messages UDP Port 162 - SNMP Trap MessagesLike FTP, SNMP uses two well-known ports to operate:Ethernet FrameIP PacketUDP DatagramSNMP MessageCRCThe Three Parts of SNMPSNMP network management is based on three parts:The Three Parts of SNMPStructure of Management Information (SMI)Rules specifying the format used to define objects managed on the network that the SNMP protocol accessesManagement Information Base (MIB)A map of the hierarchical order of all managed objects and how they are accessedSNMP Protocol Defines format of messages exchanged by management systems and agents. Specifies the Get, GetNext, Set, and Trap operations NodesNodes Items in an SNMP Network are called nodes. There are different types of nodes.Managed nodesManagement nodesNodes that are not manageable by SNMPTypically runs an agent process that services requests from a management nodeTypically a workstation running some network management & monitoring softwareA node may not support SNMP, but may be manageable by SNMP through a proxy agent running on another machineNodes 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 NamesCommunity 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 AgentsSNMP AgentsTwo basic designs of agents Extendible AgentsOpen, modular design allows for adaptations to new management data and operational requirements Proxy & Gateway AgentsProxy & Gateway 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 Basic OperationsFour Basic Operations GetGetNextSetTrapRetrieves the value of a MIB variable stored on the agent machine (integer, string, or address of another MIB variable)Retrieves the next value of the next lexical MIB variableChanges the value of a MIB variableAn unsolicited notification sent by an agent to a management application (typically a notification of something unexpected, like an error)TrapsTraps 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, UnknownTrap ReceiversTrap 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 alpha-numeric page to the network administrator’s pager that says: Your PDC just Blue-Screened at 03:46AM. Have a nice day. :)Languages of SNMPLanguages of SNMP Structure of Management Information (SMI)Abstract Syntax Notation One (ASN.1)Basic Encoding Rules (BER)specifies the format used for defining managed objects that are accessed via the SNMP protocolused to define the format of SNMP messages and managed objects (MIB modules) using an unambiguous data description formatused to encode the SNMP messages into a format suitable for transmission across a networkSMIv1SMIv1 Structure of Management InformationSMIv1 is described in RFCs 1155, 1212, 1215These 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 objectSMIv2SMIv2 Structure of Management InformationSMIv2 is described in RFCs 1442, 1443, 1444These 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 SMIv2ASN.1ASN.1 Abstract Syntax Notation OneASN.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 keywordBERBER Basic Encoding RulesThe 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 Data TypesINTEGER -- signed 32-bit integer OCTET STRING OBJECT IDENTIFIER (OID) 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 typesSNMP Data Types Yellow items defined by ASN.1 Orange items defined by RFC 1155 Managed “Objects” & MIBsManaged “Objects” & 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 cfrancois@acm.org (360)650-0000” ::= { system 4 }Basic Message FormatBasic Message Format Message LengthMessage VersionCommunity StringPDU HeaderPDU BodyMessage PreambleSNMP Protocol Data Unitnull PDU BodySNMP Message PreamblePDU HeaderSNMP Message FormatsCommercial SNMP ApplicationsCommercial SNMP ApplicationsHere 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 & Windows NT 5.0SNMP & Windows NT 5.0Proposed features of the Windows NT5 SNMP ServiceFull 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 wellSNMP RFC’sSNMP RFC’s