Net-Snmp安裝參照連結完成並測試是否安裝完成。

想要在任何地方使用需更新環境變數，新增snmp的路徑到~/.bashrc中

一、snmpd.conf

snmpd.conf是snmp的基本環境配置，在上述連結中有說明如何修改。在這裡要注意的是如果要使用子代理模式，需要在conf配置中新增“master    agentx”開啟snmp主代理模式。以下是conf配置檔案：

###############################################################################
#
# EXAMPLE.conf:
#   An example configuration file for configuring the Net-SNMP agent ('snmpd')
#   See the 'snmpd.conf(5)' man page for details
#
#  Some entries are deliberately commented out, and will need to be explicitly activated
#
###############################################################################
#
#  AGENT BEHAVIOUR
#


#  Listen for connections from the local system only
#agentAddress  udp:127.0.0.1:161
#  Listen for connections on all interfaces (both IPv4 *and* IPv6)
#agentAddress udp:161,udp6:[::1]:161
agentAddress  udp:161




###############################################################################
#
#  SNMPv3 AUTHENTICATION
#
#  Note that these particular settings don't actually belong here.
#  They should be copied to the file /var/net-snmp/snmpd.conf
#     and the passwords changed, before being uncommented in that file *only*.
#  Then restart the agent


#  createUser authOnlyUser  MD5 "remember to change this password"
#  createUser authPrivUser  SHA "remember to change this one too"  DES
#  createUser internalUser  MD5 "this is only ever used internally, but still change the password"


#  If you also change the usernames (which might be sensible),
#  then remember to update the other occurances in this example config file to match.






###############################################################################
#
#  ACCESS CONTROL
#


                                                 #  system + hrSystem groups only
view   systemonly  included   .1.3.6.1.2.1.1
view   systemonly  included   .1.3.6.1.2.1.25.1
view   all         included   .1             # Full access from the local host
#rocommunity public  localhost
                                           #  Default access to basic system info
 rocommunity public  default 
 rwcommunity public  default


                                                 #  Full access from an example network
                                                 #     Adjust this network address to match your local
                                                 #     settings, change the community string,
                                                 #     and check the 'agentAddress' setting above
#rocommunity secret  10.0.0.0/16


                                                 #  Full read-only access for SNMPv3
 rouser   authOnlyUser
                                                 #  Full write access for encrypted requests
                                                 #     Remember to activate the 'createUser' lines above
#rwuser   authPrivUser   priv


#  It's no longer typically necessary to use the full 'com2sec/group/access' configuration
#  r[ou]user and r[ow]community, together with suitable views, should cover most requirements






###############################################################################
#
#  SYSTEM INFORMATION
#


#  Note that setting these values here, results in the corresponding MIB objects being 'read-only'
#  See snmpd.conf(5) for more details
sysLocation    Sitting on the Dock of the Bay
sysContact     Me <
 
[email protected]>
                                                 # Application + End-to-End layers
sysServices    72




#
#  Process Monitoring
#
                               # At least one  'mountd' process
proc  mountd
                               # No more than 4 'ntalkd' processes - 0 is OK
proc  ntalkd    4
                               # At least one 'sendmail' process, but no more than 10
proc  sendmail 10 1


#  Walk the UCD-SNMP-MIB::prTable to see the resulting output
#  Note that this table will be empty if there are no "proc" entries in the snmpd.conf file




#
#  Disk Monitoring
#
                               # 10MBs required on root disk, 5% free on /var, 10% free on all other disks
disk       /     10000
disk       /var  5%
includeAllDisks  10%


#  Walk the UCD-SNMP-MIB::dskTable to see the resulting output
#  Note that this table will be empty if there are no "disk" entries in the snmpd.conf file




#
#  System Load
#
                               # Unacceptable 1-, 5-, and 15-minute load averages
load   12 10 5


#  Walk the UCD-SNMP-MIB::laTable to see the resulting output
#  Note that this table *will* be populated, even without a "load" entry in the snmpd.conf file






###############################################################################
#
#  ACTIVE MONITORING
#


                                    #   send SNMPv1  traps
# trapsink     localhost public
                                    #   send SNMPv2c traps
trap2sink    localhost public
                                    #   send SNMPv2c INFORMs
#informsink   localhost public


#  Note that you typically only want *one* of these three lines
#  Uncommenting two (or all three) will result in multiple copies of each notification.




#
#  Event MIB - automatically generate alerts
#
                                   # Remember to activate the 'createUser' lines above
iquerySecName   internalUser       
rouser          internalUser
                                   # generate traps on UCD error conditions
defaultMonitors          yes
                                   # generate traps on linkUp/Down
linkUpDownNotifications  yes






###############################################################################
#
#  EXTENDING THE AGENT
#


#
#  Arbitrary extension commands
#
 extend    test1   /bin/echo  Hello, world!
 extend-sh test2   echo Hello, world! ; echo Hi there ; exit 35
#extend-sh test3   /bin/sh /tmp/shtest


#  Note that this last entry requires the script '/tmp/shtest' to be created first,
#    containing the same three shell commands, before the line is uncommented


#  Walk the NET-SNMP-EXTEND-MIB tables (nsExtendConfigTable, nsExtendOutput1Table
#     and nsExtendOutput2Table) to see the resulting output


#  Note that the "extend" directive supercedes the previous "exec" and "sh" directives
#  However, walking the UCD-SNMP-MIB::extTable should still returns the same output,
#     as well as the fuller results in the above tables.




#
#  "Pass-through" MIB extension command
#
#pass .1.3.6.1.4.1.8072.2.255  /bin/sh       PREFIX/local/passtest
#pass .1.3.6.1.4.1.8072.2.255  /usr/bin/perl PREFIX/local/passtest.pl


# Note that this requires one of the two 'passtest' scripts to be installed first,
#    before the appropriate line is uncommented.
# These scripts can be found in the 'local' directory of the source distribution,
#     and are not installed automatically.


#  Walk the NET-SNMP-PASS-MIB::netSnmpPassExamples subtree to see the resulting output




#
#  AgentX Sub-agents
#
                                           #  Run as an AgentX master agent
 master          agentx
                                           #  Listen for network connections (from localhost)
                                           #    rather than the default named socket /var/agentx/master
#agentXSocket    tcp:localhost:705
mibs +MY-MIB

mibs +TEST-MIB
 

Note:#為註釋

二、自定義MIB

MIB的編寫和講解參照了前輩的部落格：https://blog.csdn.net/shanzhizi/article/details/11769491。講述的很清楚了。

這裡要注意的是在編寫完直接的MIB後，需要放入snmp的search path，一般預設的地方是：

1.  /root/.snmp/mibs 

2.  /usr/local/snmp/share/snmp/mibs

或者使用命令net-snmp-config --default-mibdirs，即可獲得路徑。詳情見：載入第三方庫

以下是我參照寫的mib：

--MY-MIB 
                MY-MIB DEFINITIONS ::= BEGIN
IMPORTS
            OBJECT-GROUP, MODULE-COMPLIANCE, NOTIFICATION-GROUP
                FROM SNMPv2-CONF
            enterprises, Integer32, Unsigned32, OBJECT-TYPE, MODULE-IDENTITY,
            NOTIFICATION-TYPE
                FROM SNMPv2-SMI
            DisplayString
                FROM SNMPv2-TC;
-- 
        -- 1.3.6.1.4.1.26536   
        Test MODULE-IDENTITY
            LAST-UPDATED "201807050918Z"
            ORGANIZATION
                ""
            CONTACT-INFO
                ""
            DESCRIPTION
                "Video's Server MIB."
            ::= { enterprises 26536 }
--  Node definitions  
-- This part will include all details about the Test.  
        -- 1.3.6.1.4.1.26536.1  
        Time OBJECT IDENTIFIER ::= { Test 1 }
        -- 1.3.6.1.4.1.26536.1.1  
        GetTime OBJECT-TYPE
            SYNTAX DisplayString (SIZE (0..100))
            MAX-ACCESS read-only
            STATUS current
            DESCRIPTION
                ""
            ::= { Time 1 }
    END
 

-- MY-MIB.my 

Note:--為註釋

Note:把該MIB放入search path，使用snmptranslate -Tp -IR  xxx::xx來驗證是否載入的時候，可能會出現"Unknown Object Identifier" 這樣的錯誤。是因為未將該MIB放入CONF檔案內。解決方法及注意事項見載入第三方庫。如上方conf配置中mibs +xxx所示， xxx即如MyMIB DEFINITIONS::=BEGIN這句定義中的MyMIB.

三、生成原始碼

mib2c可以根據mib庫生成對應的原始碼，有多種模板，這裡我們要生成子代理的程式碼，所以選擇是固定的，執行env MIBS"+/usr/local/share/snmp/mibs/Test-MIB.my" mib2c Test，會引導你逐漸生成Test.h和Test.c, 先選2再選1。

在生成的.c檔案中修改xxx或者TODO成自己的，

執行net-snmp-config --compile-subagent Test Test.c，就生成了Test程式，Test為可執行程式名（可自定義），Test.c是由你MIB生成的.c檔案。可參照：代理agent。

最後用snmpget 或者snmpwalk等命令測試。

PS:記錄下自己的過程。