snmp.conf 文件

NAME

snmp.conf - configuration files for the Net-SNMP applications

 

# 注释 ：snmp.conf 文件是配置 Net-SNMP 应用程序的文件。

 

# 这里的应用程序包括 snmpwalk ，snmmpget 这样的客户端程序，也包括 snmpd ，snmptrapd 这样的守护进程

 

---

DESCRIPTION

Applications built using the Net-SNMP libraries typically use one or more configuration files to control various aspects of their operation. These files (snmp.conf and snmp.local.conf) can be located in one of several locations, as described in the (5) manual page.

 

# 注释 ：Net-SNMP 所提供的应用程序使用1个获知多个配置文件来控制不同的操作。

 

# 例如 snmp.conf 和 snmp.local.conf

In particular, /etc/snmp/snmp.conf is a common file, containing the settings shared by all users of the system. ~/.snmp/snmp.conf is a personal file, with the settings specific to a particular user.

# 注释 ：一般情况下，/etc/snmp/snmp.conf 是一个全局性的文件，被系统的所有用户共享。

# 而 ~/.snmp/snmp.conf 是针对用户个人的配置文件

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IMPORTANT NOTE

Several of these directives may contain sensitive information (such as pass phrases). Configuration files that include such settings should only be

readable by the user concerned.

 

# 注释 ：由于这些配置文件包含有重要信息，所以它们应该只能被所有者读取

As well as application-specific configuration tokens, there are several directives that relate to standard library behaviour, relevant to most Net-SNMP applications. Many of these correspond to standard command-line options, which are described in the (1) manual page.

These directives can be divided into several distinct groups.

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CLIENT BEHAVIOUR

defaultPort PORT

defines the default UDP port that client SNMP applications will attempt to connect to. This can be overridden by explicitly including a port number in the AGENT specification. See the (1) manual page for more details.

If not specified, the default value for this token is 161.

        # 注释 ：defaultPort 定义客户端程序默认连接的 UDP 端口。默认是161

defVersion (1|2c|3)

defines the default version of SNMP to use. This can be overridden using the -v option.

        # 注释 ：defVersion (1|2c|3) 用于定义默认使用的 SNMP 版本。

 

        # 可以在命令行用 -v 选项来覆盖该值

defCommunity STRING

defines the default community to use for SNMPv1 and SNMPv2c requests. This can be overridden using the -c option.

        # 注释 ：defCommunity 定义 SNMP v1 和 SNMP v2c 默认使用的 community string

 

        # 可以在命令行用 -c 选项来覆盖该值

dumpPacket yes

defines whether to display a hexadecimal dump of the raw SNMP requests sent and received by the application. This is equivalent to the -d option.

        # 注释 ：dumpPacket yes 表示是否显示捕捉到16进制格式的原始 SNMP 请求和应答

 

        # 可以在命令行用 -d 选项来覆盖

doDebugging (1|0)

turns on debugging for all applications run if set to 1.

        # 注释 ：doDebugging （1|0）表示是否启用 debug 功能。1 为启用，0 为禁用

debugTokens TOKEN[,TOKEN...]

defines the debugging tokens that should be turned on when doDebugging is set. This is equivalent to the -D option.

        # 注释 ：debugTokens 定义 debug 时的 token 。等于 -D 选项

16bitIDs yes

restricts requestIDs, etc to 16-bit values.

The SNMP specifications define these ID fields as 32-bit quantities, and the Net-SNMP library typically initialises them to random values for security. However certain (broken) agents cannot handle ID values greater than 2^16 - this option allows interoperability with such agents.

        # 注释 ：16bitIDs 表示强制使用 16 bit 的请求 ID。

 

        # SNMP 处于安全期间在启动期间随即初始化。

clientaddr [:]

specifies the source address to be used by command-line applications when sending SNMP requests. See (1) for more information about the format of addresses.

This value is also used by snmpd when generating notifications.

        # 注释 ：clientaddr [transport]：[host]；[port] 用于定义发送 SNMP 请求时使用的源地址。

 

        # 当 snmpd 生成 notification 消息时就会用到

clientRecvBuf INTEGER

specifies the desired size of the buffer to be used when receiving responses to SNMP requests. If the OS hard limit is lower than the clientRecvBuf value, then this will be used instead. Some platforms may decide to increase the size of the buffer actually used for internal housekeeping.

This directive will be ignored if the platforms does not support setsockopt().

 

clientSendBuf INTEGER

is similar to clientRecvBuf, but applies to the size of the buffer used when sending SNMP requests.

noRangeCheck yes

disables the validation of varbind values against the MIB definition for the relevant OID. This is equivalent to the -Ir option.

This directive is primarily relevant to the snmpset command, but will also apply to any application that calls snmp_add_var() with a non-NULL value.

        # 注释 ：noRangeCheck yes 表示禁止检查 variable binding 中给出的值是否符合 MIB 中该对象的定义

 

        # 等于命令行的 -Ir 选项，主要用于 snmpset 命令

noTokenWarnings

disables warnings about unknown config file tokens.

 

reverseEncodeBER (1|yes|true|0|no|false)

controls how the encoding of SNMP requests is handled.

The default behaviour is to encode packets starting from the end of the PDU and working backwards. This directive can be used to disable this behaviour, and build the encoded request in the (more obvious) forward direction.

It should not normally be necessary to change this setting, as the encoding is basically the same in either case - but working backwards typically produces a slightly more efficient encoding, and hence a smaller network datagram.

---

SNMPv3 SETTINGS

defSecurityName STRING

defines the default security name to use for SNMPv3 requests. This can be overridden using the -u option.

defSecurityLevel noAuthNoPriv|authNoPriv|authPriv

defines the default security level to use for SNMPv3 requests. This can be overridden using the -l option.

If not specified, the default value for this token is noAuthNoPriv.

Note:

authPriv is only available if the software has been compiled to use the OpenSSL libraries.

defPassphrase STRING

defAuthPassphrase STRING

defPrivPassphrase STRING

define the default authentication and privacy pass phrases to use for SNMPv3 requests. These can be overridden using the -A and -X options respectively.

The defPassphrase value will be used for the authentication and/or privacy pass phrases if either of the other directives are not specified.

defAuthType MD5|SHA

defPrivType DES|AES

define the default authentication and privacy protocols to use for SNMPv3 requests. These can be overridden using the -a and -x options respectively.

If not specified, SNMPv3 requests will default to MD5 authentication and DES encryption.

Note:

If the software has not been compiled to use the OpenSSL libraries, then only MD5 authentication is supported. Neither SHA authentication nor any form of encryption will be available.

defContext STRING

defines the default context to use for SNMPv3 requests. This can be overridden using the -n option.

If not specified, the default value for this token is the default context (i.e. the empty string "").

defSecurityModel STRING

defines the security model to use for SNMPv3 requests. The default value is "usm" which is the only widely used security model for SNMPv3.

defAuthMasterKey 0xHEXSTRING

defPrivMasterKey 0xHEXSTRING

defAuthLocalizedKey 0xHEXSTRING

defPrivLocalizedKey 0xHEXSTRING

define the (hexadecimal) keys to be used for SNMPv3 secure communications. SNMPv3 keys are frequently derived from a passphrase, as discussed in the defPassphrase section above. However for improved security a truely random key can be generated and used instead (which would normally has better entropy than a password unless it is amazingly long). The directives are equivalent to the short-form command line options -3m, -3M, -3k, and -3K.

Localized keys are master keys which have been converted to a unique key which is only suitable for on particular SNMP engine (agent). The length of the key needs to be appropriate for the authentication or encryption type being used (auth keys: MD5=16 bytes, SHA1=20 bytes; priv keys: DES=16 bytes (8 bytes of which is used as an IV and not a key), and AES=16 bytes).

---

 

SERVER BEHAVIOUR

persistentDir DIRECTORY

defines the directory where snmpd and snmptrapd store persistent configuration settings.

If not specified, the persistent directory defaults to /var/net-snmp

        # 注释 ：persistentDir 定义 snmpd 和 snmptrapd 存放永久性配置文件的目录。默认是 /var/net-snmp

   

noPersistentLoad yes

noPersistentSave yes

disable the loading and saving of persistent configuration information.

Note:

This will break SNMPv3 operations (and other behaviour that relies on changes persisting across application restart). Use With Care.

tempFilePattern PATTERN

defines a filename template for creating temporary files, for handling input to and output from external shell commands. Used by the mkstemp() and mktemp() functions.

If not specified, the default pattern is /tmp/snmpdXXXXXX.

        # 注释 ：tempFilePattern 定义用于建立临时文件的文件名模式。默认是 /tmp/snmpdxxxx 。

serverRecvBuf INTEGER

specifies the desired size of the buffer to be used when receiving incoming SNMP requests. If the OS hard limit is lower than the serverRecvBuf value, then this will be used instead. Some platforms may decide to increase the size of the buffer actually used for internal housekeeping.

This directive will be ignored if the platforms does not support setsockopt(). 

serverSendBuf INTEGER

is similar to serverRecvBuf, but applies to the size of the buffer used when sending SNMP responses.

---

MIB HANDLING

mibdirs DIRLIST

specifies a list of directories to search for MIB files. This operates in the same way as the -M option - see (1) for details. Note that this value can be overridden by the MIBDIRS environment variable, and the -M option.

        # 注释 ：mibdirs 指令给出了 MIB 文件存放的位置。

 

        # 可以在命令行用 -M 选项指定。

 

        # 注释 ：不过该选项可以被 MIBDIRS 变量覆盖

mibs MIBLIST

specifies a list of MIB modules (not files) that should be loaded. This operates in the same way as the -m option - see (1) for details. Note that this list can be overridden by the MIBS environment variable, and the -m option.

        # 注释 ：mibs 指令给出了一个 snmpd 服务启动时应该加载的 MIB 模块的列表（不是文件名）。

 

        # 可以在命令行用 -m 选项指定

 

        # 注释 ：该选项可以被 MIBS 变量覆盖

mibfile FILE

specifies a (single) MIB file to load, in addition to the list read from the mibs token (or equivalent configuration). Note that this value can be overridden by the MIBFILES environment variable.

        # 注释 ：mibfile 指令给出一个单独的 MIB 文件名，表示除了 mibs 指令给出的之外，再加载该文件。

showMibErrors (1|yes|true|0|no|false)

whether to display MIB parsing errors.

        # 注释 ：showMibErrors 指令设置是否显示 MIB 解释错误

strictCommentTerm (1|yes|true|0|no|false)

whether MIB parsing should be strict about comment termination. Many MIB writers assume that ASN.1 comments extend to the end of the text line, rather than being terminated by the next "--" token. This token can be used to accept such (strictly incorrect) MIBs. 

 

mibAllowUnderline (1|yes|true|0|no|false)

whether to allow underline characters in MIB object names and enumeration values. This token can be used to accept such (strictly incorrect) MIBs.

mibWarningLevel INTEGER

the minimum warning level of the warnings printed by the MIB parser.

 

---

 

OUTPUT CONFIGURATION

logTimestamp (1|yes|true|0|no|false)

 

Whether the commands should log timestamps with their error/message logging or not. Note that output will not look as pretty with timestamps if the source code that is doing the logging does incremental logging of messages that are not line buffered before being passed to the logging routines. This option is only used when file logging is active.

 

printNumericEnums (1|yes|true|0|no|false)

 

Equivalent to -Oe.

 

printNumericOids (1|yes|true|0|no|false)

 

Equivalent to -On.

    # 注释 ：printNumbericOids 表示输出时显示数字格式的 oid ，而不是名称

 

dontBreakdownOids (1|yes|true|0|no|false)

 

Equivalent to -Ob.

 

escapeQuotes (1|yes|true|0|no|false)

 

Equivalent to -OE.

 

quickPrinting (1|yes|true|0|no|false)

 

Equivalent to -Oq.

 

printValueOnly (1|yes|true|0|no|false)

 

Equivalent to -Ov.

 

dontPrintUnits (1|yes|true|0|no|false)

 

Equivalent to -OU.

 

numericTimeticks (1|yes|true|0|no|false)

 

Equivalent to -Ot.

 

printHexText (1|yes|true|0|no|false)

 

Equivalent to -OT.

 

hexOutputLength integer

 

Specifies where to break up the output of hexadecimal strings. Set to 0 to disable line breaks. Defaults to 16.

 

suffixPrinting (0|1|2)

 

The value 1 is equivalent to -Os and the value 2 is equivalent to -OS.

 

oidOutputFormat (1|2|3|4|5|6)

 

Maps -O options as follow: -Os=1, -OS=2, -Of=3, -On=4, -Ou=5. The value 6 has no matching -O option. It suppresses output.

 

extendedIndex (1|yes|true|0|no|false)

 

Equivalent to -OX.

 

noDisplayHint (1|yes|true|0|no|false)

 

Disables the use of DISPLAY-HINT information when parsing indices and values to set. Equivalent to -Ih.

FILES

/etc/snmp/snmp.conf, /etc/snmp/snmp.local.conf - common configuration settings ~/.snmp/snmp.conf - user-specific configuration settings