Select the SNMP Device Config tab to configure agents or devices, according to the next figure.
SNMP Device Config tab
The available options on this tab are described on the next table.
Available options on the SNMP Device Config tab
Option |
Description |
|---|---|
Add |
Adds a device or agent |
Update |
Updates the selected device or agent. . Changes made without confirmation through this button will be discarded. |
Delete |
Removes the selected device or agent |
Device |
Symbolic name of a device or agent. This name is used only to identify a device for this Driver, mapping it to the IP address and UDP/IP port configured in the IP and Port options, respectively, in addition to other settings |
IP |
Informs an agent's IP address |
Port |
Informs the UDP/IP port where this agent expects a connection. The default UDP/IP port is 161, but some devices or simulators may use other ports |
Max Requests per Packet |
Maximum number of variable requests (OIDs) to perform in a single message for this agent. The more requests can be performed at each communication, the quicker and more efficient is the general scan of variables configured for this device. NOTE: Variables not declared for exclusive reception of Traps use a polling method, always respecting the maximum number of variables for each request. Please check topic Tag Reference for more information |
Version |
SNMP version used by this agent. Currently this Driver supports versions V1, V2C and V3. |
Text used as a parameter on SNMP messages to indicate the group or community of variables to which this request belongs. The most common community is public, but there can also be variables from a private community or other communities created by other companies or users. In this case, type the name of a community. If it´s necessary to use more than one community, their names must be separated by semicolons, such as "public;communityA;communityB", and the community that will be used for each tag (which can only be one) will be defined by the parameter N2 (0 = first community of the list, 1 = second community of the list, etc...) |
|
Write Community |
Value of the writing community, if it is different from the reading community. Otherwise, inform the same text added in the Read Community option |
MIB Parser |
Up to version 2.0.21 this driver was using only smidump as MIB File interpreter. This is used to generate the tag visualization at the Tag Browser, allowing to import the available tags to the application. Starting from version 2.0.22, there is an option to use snmptranslate, which can offer different results, depending on the MIB file. Use this option to choose which parser will be used. |
Browse MIBs |
Opens a dialog box to select MIB files to import, which provide the device ag database. |
Extra Modules |
List of modules imported using the Browse MIBs option |
Disable |
Disables this device, not establishing communication with this Driver when it starts, and also hides this agent from the list of devices on the Tag Browser window |
SNMP v3 - UserName |
Username to be used when using version V3. It shall be compatible with Username defined at the agent. |
SNMP v3 - Context Name |
ContextName to be used when using version V3. It shall be compatible with ContextName defined at the agent. |
SNMP v3 - Security Level |
Defines the Authentication and Privacy options. The authentication option uses a hash mechanism to know if the message has been altered during the transmission process. The privacy option means that beyond authentication, data will be crypted and not visible to an external observer. It is only possible to have privacy if there is authentication, so the possibe options are: - NoAuthNoPriv: No authentication and no privacy options and the protocol behaves similarly to V2C version; - AuthNoPriv: Uses authentication but no privacy - AuthPriv: Uses authentication and privacy. |
SNMP v3 - Auth Passphrase |
Informs the password used for authentication. It shall be coincident with the password defined at the agent. |
SNMP v3 - Auth Style |
Algorithm for authentication. This algorithm is also used to transform the authentication and privacy passwords into private keys, in order to avoid password plain text exposure. The options are: HMAC-MD5, HMAC-SHA1-96 and HMAC-SHA2-256. |
SNMP v3 - Priv Passphrase |
Informs the password used for privacy. The password shall be coincident with the one defined at the agent. |
SNMP v3 - Priv Style |
Algorithm for privacy. The options are: DES, 3DES, AES128, AES196 and AES256. |
Important Note about authentication and cryptographic algorithms at SNMP V3
Actually the official SNMP specification defines for authentication only the algorithms MD5 e SHA1-96, and for cryptography, DES e AES 128. However, as time passes new algorithms have been developed, which use bigger keys to avoid communication violation, using for example the brute force method. Several manufacturers have adopted on their own decision these new algorithms.
If you choose an authentication option that generates a key smaller than the minimum necessary for a particular cryptography algorithm, this driver uses a key extension method described at the document Reeder 3DES Internet draft (https://tools.ietf.org/html/draft-reeder-snmpv3-usm-3desede-00), which is used by Cisco and other manufacturers. Note that this mechanism is not used when the authentication algorithm already provides a key at the proper size.
The standard key sizes are the following:
Authentication:
MD5: 16 bytes
SHA1-96: 20 bytes
SHA2-256: 32 bytes
Cryptography:
DES: needs a 16-byte key
3DES: needs a 32-byte key
AES128, AES192 e AES256: a Key of 16, 24 and 32 bytes are respectively needed.
In this way, if you choose MD5 as authentication and 3DES as cryptography, the driver will extended the key from 16 to 32 bytes.
MIB Files
Tags of an agent can be created by importing files known as MIBs (Management Information Base), which are obtained via public domain (standardized MIBs based on standards such as IETF, IRTF, IANA, etc.) or supplied by agent and device manufacturers.
Click Browse MIBs to open a dialog box to select MIB files for importing. After selecting all files, an entry is then created in the device declaration section corresponding to that agent, in addition to a folder on the Tag Browser window containing all identified Tags.
Along with this Driver there is a mibs folder with a set of standard MIB files nearly complete and updated, as shown on the next figure.
Window to select MIB files
If users must import MIB files provided by device manufacturers or by third-parties, these files must be copied to the mibs/site folder.
For this import process to succeed, each MIB file must have the exact same name of its module, that is, the name found before the keyword DEFINITIONS at the beginning of a file, without any extension or additional characters.
After selecting all MIB files the import process is performed and, if successful, the list of modules of the selected device is expanded with the new modules, which is equivalent of clicking Update. Thus, folders containing all objects imported from E3's Tag Browser window are available, maintaining the hierarchy of modules, nodes, tables, rows, columns, groups, notifications, and scalars for each MIB in each device.
NOTE |
To add the same MIB file to several devices, users must add it to the Extra Modules option for each one of these agents. |
The import process provides Tags with the parameters described on the next table.
Tag parameters of the import process
Parameter |
Description |
|---|---|
Name |
Default symbolic name of a scalar or table column, as retrieved from the MIB file |
ParamDevice |
Name of a user-defined agent on the list of devices or agents |
ParamItem |
Default numeric value of the OID (Object Identifier), already in ASN.1 (Abstract Syntax Notation) format, as retrieved from the MIB file.
When the tag is referenced to a scalar object (i.e. a simple instance), the OID address will end up with ".0".
When the tag represents a table column, it will be created with a default row index = 1, indicated by brackets "[1]".
SNMP tables can contain 0,1,2...N rows. The tags (which are the columns) will be created by the tag browser with the row 1 address. If you want tags for other rows, you can change the index, or create tag copies pointing to other rows. Example:
Default Tag for a column named lldpPortNum: lldpPortNum.1 = 1.0.8802.1.1.2.1.3.7.1.1[1]
To obtain tags addressed for other rows, copies can be created, like: lldpPortNum.0 = 1.0.8802.1.1.2.1.3.7.1.1[0] lldpPortNum.2 = 1.0.8802.1.1.2.1.3.7.1.1[2] lldpPortNum.3 = 1.0.8802.1.1.2.1.3.7.1.1[3]
If the table doesn´t contain the requested row or cell, the tag will have bad quality (informed at the Quality property). |