How to configure SNMP v3 on Cisco Switch, Router, ASA, Nexus
Configuring SNMP This chapter describes how to configure the Simple Network Management Protocol (SNMP) on the Catalyst and S switches. Unless otherwise noted, the term switch refers to a standalone switch and a switch stack. Note Stacking is supported only on Catalyst S switches running the LAN base mybajaguide.com Size: KB. Configuring SNMP This chapter describes how to configure the Simple Network Management Protocol (SNMP) on the Catalyst switch. Note For complete syntax and usage information for the commands used in this chapter, see the command reference for this release and to the Cisco IOS Configuration Fundamentals Command Reference, Release
In the context of this document, configure is defined as verify, enable, csco, and disable SNMP community strings. The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared default configuration.
If your network is live, make sure swwitch you understand the potential impact of any command. Refer to the Cisco Technical Tips Conventions for more information on document conventions. If any SNMP commands are listed, you can modify or disable them. In this sample output, "public" is the read-only community string and "private" is the read-write community string.
Alternatively, execute the show snmp command in the enable mode. If you see this message, it also indicates that SNMP is not enabled on the router:. Router hpw no snmp-server community public RO where "public" is the Read-only community string. Router config hwo snmp-server community private RW where "private" is the Read-write community string.
Execute the show module command in order to what is the punishment for racial discrimination the system swtich and locate the RSM module.
Here is an example:. After you identify the Mod number, start a "session" to the RSM module. In this sample output, "public" is the Read-only community string and "private" is the Read-write community string. Alternatively, you can execute the show snmp command in the enable mode.
If you see this message, it also indicates that SNMP is not enabled on the router. You can complete the same procedure to modify SNMP as 260 in the router example. You can complete the same procedure to disable SNMP as described in the router example. You can complete the same procedure to enable SNMP as described in the. Execute the show module command in order to display the system modules and locate the MSFC module.
You can complete the same configur in order to modify SNMP as described in the router example. You can complete the same procedure in order to disable SNMP as described in the router example. On Catalyst switches such as the, and clnfigure that run a regular catalyst Operating System OSSNMP is enabled by default with how to setup vpn between two computers community strings set to:.
With these community strings and the IP address of your switch's management interface, anyone is able to reconfigure the device. You must change the community strings on the Catalyst switch immediately after you set the device on the network. This is very important.
Note: The Catalyst, and series switches do not have Start-up configurations. That is why there is no write memory command in these switches compared to the routers. Execute the show snmp command in order to display the current SNMP information and look for the community-access information. The command overwrites the existing community string if the switch has one. Note: Cat OS supports only one community string for each read-only, read-write and read-write-all communities. You can not configure multiple community xnmp, unlike Cisco IOS.
As you can see, the swutch for "Community-String" is blank. This indicates how to give a motorboat both the read-only and read-write community strings are deleted or removed.
Jan 31, · To configure SNMP on the switch, you define the relationship between the manager and the agent. The SNMP agent contains MIB variables whose values the SNMP manager can request or change. A manager can get a value from an agent or store a value into the agent. Mar 18, · Consolidated Platform Configuration Guide, Cisco IOS Release (6)E (Catalyst CX and CX Switches) Chapter Title. Configuring Simple Network Management Protocol. PDF - Complete Book ( MB) PDF - This Chapter ( . Apr 23, · in the configuration mode enter use the folowwing command: switch (config)# snmp-server community test RO // set snmp community test for read only (could be enough for you) There are much more options like securing via snmpv3, source interface or access list security for my showing command. look here: .
It has these features:. SNMPv3 provides secure access to devices by authenticating and encrypting packets over the network and includes these security features:. Encryption—Mixes the contents of a package to prevent it from being read by an unauthorized source.
SNMPv2C includes a bulk retrieval function and more detailed error message reporting to management stations. The bulk retrieval function retrieves tables and large quantities of information, minimizing the number of round-trips required. The SNMPv2C improved error-handling includes expanded error codes that distinguish different kinds of error conditions; these conditions are reported through a single error code in SNMPv1.
SNMPv3 provides for both security models and security levels. A security model is an authentication strategy set up for a user and the group within which the user resides. A security level is the permitted level of security within a security model. A combination of the security level and the security model determine which security method is used when handling an SNMP packet.
The following table identifies characteristics and compares different combinations of security models and levels:. SNMP is an application-layer protocol that provides a message format for communication between managers and agents.
The agent and MIB reside on the device. To configure SNMP on the device , you define the relationship between the manager and the agent. A manager can get a value from an agent or store a value into the agent. The agent gathers data from the MIB, the repository for information about device parameters and network data. The agent can also respond to a manager's requests to get or set data. An agent can send unsolicited traps to the manager.
Traps are messages alerting the SNMP manager to a condition on the network. Traps can mean improper user authentication, restarts, link status up or down , MAC address tracking, closing of a TCP connection, loss of connection to a neighbor, or other significant events. Examples of trap conditions include, but are not limited to, when a port or module goes up or down, when spanning-tree topology changes occur, and when authentication failures occur.
In order for the NMS to access the device , the community string definitions on the NMS must match at least one of the three community string definitions on the device. Read-only RO —Gives all objects in the MIB except the community strings read access to authorized management stations, but does not allow write access.
Read-write RW —Gives all objects in the MIB read and write access to authorized management stations, but does not allow access to the community strings. When a cluster is created, the command device manages the exchange of messages among member devices and the SNMP application. The Network Assistant software appends the member device number esN, where N is the device number to the first configured RW and RO community strings on the command device and propagates them to the member devices.
Cisco Prime Infrastructure software uses the device MIB variables to set device variables and to poll devices on the network for specific information.
The results of a poll can be displayed as a graph and analyzed to troubleshoot internetworking problems, increase network performance, verify the configuration of devices, monitor traffic loads, and more.
The agent can send traps, or notification of certain events, to the SNMP manager, which receives and processes the traps. Traps alert the SNMP manager to a condition on the network such as improper user authentication, restarts, link status up or down , MAC address tracking, and so forth. SNMP notifications can be sent as traps or inform requests. In command syntax, unless there is an option in the command to select either traps or informs, the keyword traps refers to either traps or informs, or both.
Use the snmp-server host command to specify whether to send SNMP notifications as traps or informs. Traps are unreliable because the receiver does not send an acknowledgment when it receives a trap, and the sender cannot determine if the trap was received.
If the sender does not receive a response, the inform request can be sent again. Because they can be resent, informs are more likely than traps to reach their intended destination. The characteristics that make informs more reliable than traps also consume more resources in the device and in the network. Unlike a trap, which is discarded as soon as it is sent, an inform request is held in memory until a response is received or the request times out. Traps are sent only once, but an inform might be resent or retried several times.
The retries increase traffic and contribute to a higher overhead on the network. Therefore, traps and informs require a trade-off between reliability and resources. If it is important that the SNMP manager receive every notification, use inform requests.
If traffic on the network or memory in the device is a concern and notification is not required, use traps. In an NMS, the IF-MIB generates and assigns an interface index ifIndex object value that is a unique number greater than zero to identify a physical or a logical interface.
When the device reboots or the device software is upgraded, the device uses this same value for the interface. For example, if the device assigns a port 2 an ifIndex value of , this value is the same after the device reboots. The device uses one of the values in the following table to assign an ifIndex value to an interface:. If the device starts and the device startup configuration has at least one snmp-server global configuration command, the SNMP agent is enabled.
When configuring an SNMP group, do not specify a notify view. The snmp-server host global configuration command auto-generates a notify view for the user and then adds it to the group associated with that user. Modifying the group's notify view affects all users associated with that group.
To configure a remote user, specify the IP address or port number for the remote SNMP agent of the device where the user resides. Before you configure remote users for a particular agent, configure the SNMP engine ID, using the snmp-server engineID global configuration command with the remote option. If you do not configure the remote engine ID first, the configuration command fails.
If a local user is not associated with a remote host, the device does not send informs for the auth authNoPriv and the priv authPriv authentication levels.
A user's password entered on the command line is converted to an MD5 or SHA security digest based on the password and the local engine ID. The command-line password is then destroyed, as required by RFC Because of this deletion, if the value of the engine ID changes, the security digests of SNMPv3 users become invalid, and you need to reconfigure SNMP users by using the snmp-server user username global configuration command.
Similar restrictions require the reconfiguration of community strings when the engine ID changes. You reenable all versions of the SNMP agent by the first snmp-server global configuration command that you enter. The SNMP agent is enabled by the first snmp-server global configuration command entered on the device. Enters global configuration mode. Returns to privileged EXEC mode. Verifies your entries. Optional Saves your entries in the configuration file. An access list of IP addresses of the SNMP managers that are permitted to use the community string to gain access to the agent.
Follow these steps to configure a community string on the device. For string , specify a string that acts like a password and permits access to the SNMP protocol. You can configure one or more community strings of any length. Optional For view , specify the view record accessible to the community. Optional Specify either read-only ro if you want authorized management stations to retrieve MIB objects, or specify read-write rw if you want authorized management stations to retrieve and modify MIB objects.
By default, the community string permits read-only access to all objects. Optional For access-list-number , enter an IP standard access list numbered from 1 to 99 and to For access-list-number , enter the access list number specified in Step 3. The deny keyword denies access if the conditions are matched. The permit keyword permits access if the conditions are matched. For source , enter the IP address of the SNMP managers that are permitted to use the community string to gain access to the agent.
Optional For source-wildcard , enter the wildcard bits in dotted decimal notation to be applied to the source. Place ones in the bit positions that you want to ignore. Recall that the access list is always terminated by an implicit deny statement for everything.
To disable access for an SNMP community, set the community string for that community to the null string do not enter a value for the community string. To remove a specific community string, use the no snmp-server community string global configuration command. Follow these steps to configure SNMP groups and users on the device.
Configures a name for either the local or remote copy of SNMP. You need not specify the entire character engine ID if it has trailing zeros. Specify only the portion of the engine ID up to the point where only zeros remain in the value. The Step Example configures an engine ID of The default is Configures a new SNMP group on the remote device.
For group-name , specify the name of the group. Specify one of the following security models:. It allows transmission of informs and integers twice the normal width.
This is the default if no keyword is specified. Optional Enter read readview with a string not to exceed 64 characters that is the name of the view in which you can only view the contents of the agent. Optional Enter write writeview with a string not to exceed 64 characters that is the name of the view in which you enter data and configure the contents of the agent. Optional Enter notify notifyview with a string not to exceed 64 characters that is the name of the view in which you specify a notify, inform, or trap.
Optional Enter access access-list with a string not to exceed 64 characters that is the name of the access list. The username is the name of the user on the host that connects to the agent. The group-name is the name of the group to which the user is associated.