net-snmp配置开发及注意事项

 

一.安装及配置SNMPwin32环境)

1.下载

www.sourceforge.net下载到最新的net-snmp(目前最新版本 5.4.1 net-snmp-5.4.1.zip

2.解压编译

解压后,可以看到有一个win32目录,里面存放的是和win32环境相关的文件,有3dsw

       libsdll.dsw             编译lib文件和dll文件的工程

       win32.dsw            编译lib文件和工具文件如snmpget,snmpset的工程

       win32sdk.dsw              类似于win32.dsw,区别在于:需要安装Platform SDK。如果需要agent能支持 interfaces等一些高级功能,必须用此工程编译。XPSP2 Platform SDK的下载地址

http://www.microsoft.com/msdownload/platformsdk/sdkupdate/XPSP2FULLInstall.htm

       只需要安装Core SDK就可以了,安装完后需要从开始菜单中Register一下。

       注意编译的顺序,最好先编译libsdll.dsw,把netsnmp.libnetsnmpagent.libnetsnmphelpers.libnetsnmpmibs.libnetsnmptrapd.lib文件先编译好,再编译win32sdk.dsw中的项目。

3.安装

运行win32目录下的install-net-snmp.bat批处理文件,会把上一步编译生成的文件及相关的头文件等拷贝到c:/usr目录。

4.配置

       c:/usr/etc/snmp目录添加配置文件snmpd.conf,添加如下内容:

rocommunity  public

rwcommunity  private

       它表示的含义是,启动agent服务后,通过public共同体是只读的,private共同体可读也可写。

       在命令行运行如下命令,将snmp注册为windows的服务:

              cmd>”C:/usr/bin/snmpd.exe” –register -Lf "C:/usr/log/snmpd.log"

       注册成功后可以在【控制面板】->【管理工具】->【服务】中看到刚注册的服务,服务名是:net-snmp agent

5.运行

       cmd>net start “net-snmp agent”

       如果正常,会得到启动服务成功的提示

6.验证

       cmd>snmpget –v 2c –c public localhost 1.3.6 .1.2.1.1.5.0

       cmd> snmpset -v 2c -c private localhost sysContact.0 = piyeyong

       如果正常,会的到取得和设置成功的提示,出错会给出错误提示。

二.MIB文件编写

       MIB文件会存放于C:/usr/share/snmp/mibs/目录下,是*.txt,纯文本文件,可以直接打开查看和更改。RFC1213中定义的MIB节点信息的定义存放与RFC1213-MIB.txt,这些节点是比较重要的,会经常用到。

       如果要扩展MIB,应该定义在 1.3.6 .1.4.1(.iso.org.dod.internet.private.enterprises)子树下。自定义MIB的节点,只需要描述该节点的SYNTAXACCESSSTATUSDESCRIPTION等属性及它属于父节点的第几个子节点即可。如下所示,为扩展MIB的一个简单例子:

PROBA-MIB DEFINITIONS::=BEGIN

       IMPORTS     

              enterprises,OBJECT-TYPE,Integer32,TimeTicks

                    FROM SNMPv2-SMI

       TEXTUAL-CONVENTION,  DisplayString FROM SNMPv2-TC;

 

-- proba node

       proba OBJECT IDENTIFIER::={enterprises 8888}

 

baseinfo     OBJECT IDENTIFIER ::= { proba 1 }

 

-- company name

       probaCompName OBJECT-TYPE

              SYNTAX DisplayString (SIZE (0..255))

              ACCESS read-only

              STATUS mandatory

              DESCRIPTION "The Name of company"

              ::={baseinfo 1}

 

-- company location

       probaLocation OBJECT-TYPE

              SYNTAX DisplayString (SIZE (0..255))

              ACCESS read-write

              STATUS mandatory

              DESCRIPTION "The Location of company"

              ::={baseinfo 2}

             

-- employee number

       probaEmployeeNumber OBJECT-TYPE

              SYNTAX INTEGER

              ACCESS read-only

              STATUS mandatory

              DESCRIPTION "The number of employee"

              ::={baseinfo 3}

END

三.Agent端开发

       在上一步中定义好MIB的结构后,现在就开始编码实现定义好的节点。net-snmp提供了一个MIB 2C 工具,利用它可以根据MIB的定义和配置文件自动生成*.c*.h模板文件,然后只需要在相应位置添加对节点数据的处理就可以了。

1.配置net-snmpperl模块

       用使用mib 2c 工具,需要perl模块的支持,可以从http://www.ActiveState.com/ActivePerl下载,目前最新版是 5.8.8

       net-snmp源文件的perl目录下,运行以下命令:

       cmd>perl makefile.pl

如果成功,会生成makefile文件

cmd>nmake

cmd>nmake install

       这时,会将net-snmp相关的perl模块编译好并安装到c:/perl/site/lib目录下。

       注:有时候运行nmake会失败,把其它机器上安装好的c:/perl/site/lib目录下的文件拷贝过来,也可以运行。

2.mib 2c 生成模板源代码

       运行以下命令:

       cmd>mib 2c -c mib 2c .scalar.conf baseinfo

       会按照模板配置文件mib 2c .scalar.conf生成baseinfo.hbaseinfo.c文件。注意:baseinfo是上一步在MIB中定义的proba下的一个节点。在baseinfo.c中有很多/* XXX 注释*/的地方,这些地方是需要我们修改,填上我们对节点数据的处理代码。

3.read-only节点的代码修改

       probaCompName节点为例:

int

handle_probaCompName(netsnmp_mib_handler *handler,

                          netsnmp_handler_registration *reginfo,

                          netsnmp_agent_request_info   *reqinfo,

                          netsnmp_request_info         *requests)

{

    /* We are never called for a GETNEXT if it's registered as a

       "instance", as it's "magically" handled for us.  */

 

    /* a instance handler also only hands us one request at a time, so

       we don't need to loop over a list of requests; we'll only get one. */

   

    switch(reqinfo->mode) {

 

        case MODE_GET:

            snmp_set_var_typed_value(requests->requestvb, ASN_OCTET_STR,

                                     (u_char *)"proba" /* XXX: a pointer to the scalar's data */,

                                     strlen("proba")/* XXX: the length of the data in bytes */);

            break;

 

 

        default:

            /* we should never get here, so this is a really bad error */

            snmp_log(LOG_ERR, "unknown mode (%d) in handle_probaCompName/n", reqinfo->mode );

            return SNMP_ERR_GENERR;

    }

 

    return SNMP_ERR_NOERROR;

}

       从上面的代码看出,只需在两处/* XXX 注释 */的代码处填上这个节点的数据即可,管理站在执行get命令时这个值会返回给管理站。

4.read-write节点的代码修改

       probaLocation节点为例:

 

static char location[256];

void

init_baseinfo(void)

{

       memset(location, '/0', sizeof location);

       memcpy(location, " beijing ", sizeof " beijing ");

       。。。。。。

}

int

handle_probaLocation(netsnmp_mib_handler *handler,

                          netsnmp_handler_registration *reginfo,

                          netsnmp_agent_request_info   *reqinfo,

                          netsnmp_request_info         *requests)

{

    int ret;

 

    /* We are never called for a GETNEXT if it's registered as a

       "instance", as it's "magically" handled for us.  */

 

    /* a instance handler also only hands us one request at a time, so

       we don't need to loop over a list of requests; we'll only get one. */

   

    switch(reqinfo->mode) {

 

        case MODE_GET:

            snmp_set_var_typed_value(requests->requestvb, ASN_OCTET_STR,

                                     (u_char *)location /* XXX: a pointer to the scalar's data */,

                                     strlen(location)/* XXX: the length of the data in bytes */);

            break;

 

        /*

         * SET REQUEST

         *

         * multiple states in the transaction.  See:

         * http://www.net-snmp.org/tutorial-5/toolkit/mib_module/set-actions.jpg

         */

        case MODE_SET_RESERVE1:

                /* or you could use netsnmp_check_vb_type_and_size instead */

            ret = netsnmp_check_vb_type(requests->requestvb, ASN_OCTET_STR);

            if ( ret != SNMP_ERR_NOERROR ) {

                netsnmp_set_request_error(reqinfo, requests, ret );

            }

            break;

 

        case MODE_SET_RESERVE2:

            /* XXX malloc "undo" storage buffer */

            if (0/* XXX if malloc, or whatever, failed: */) {

                netsnmp_set_request_error(reqinfo, requests, SNMP_ERR_RESOURCEUNAVAILABLE);

            }

            break;

 

        case MODE_SET_FREE:

            /* XXX: free resources allocated in RESERVE1 and/or

               RESERVE2.  Something failed somewhere, and the states

               below won't be called. */

            break;

 

        case MODE_SET_ACTION:

            /* XXX: perform the value change here */

            if (0/* XXX: error? */) {

                netsnmp_set_request_error(reqinfo, requests, SNMP_ERR_COMMITFAILED/* some error */);

            }

            break;

 

        case MODE_SET_COMMIT:

            /* XXX: delete temporary storage */

                     memcpy(location, requests->requestvb->buf, requests->requestvb->val_len);

                     location[requests->requestvb->val_len] = '/0';

            if (0/* XXX: error? */) {

                /* try _really_really_ hard to never get to this point */

                netsnmp_set_request_error(reqinfo, requests, SNMP_ERR_COMMITFAILED);

            }

            break;

 

        case MODE_SET_UNDO:

            /* XXX: UNDO and return to previous value for the object */

            if (0/* XXX: error? */) {

                /* try _really_really_ hard to never get to this point */

                netsnmp_set_request_error(reqinfo, requests, SNMP_ERR_UNDOFAILED);

            }

            break;

 

        default:

            /* we should never get here, so this is a really bad error */

            snmp_log(LOG_ERR, "unknown mode (%d) in handle_probaLocation/n", reqinfo->mode );

            return SNMP_ERR_GENERR;

    }

 

    return SNMP_ERR_NOERROR;

}

对于read-write节点的处理要复杂一点,对每一次管理站的set请求,代理站的处理会经过如下图所示的步骤:

       从图中可以看出,通过这种机制,在处理出错的时候,可以根据需要实现回滚操作。

5.重新编译

       按照一下步骤重新编译工程:

       1)把baseinfo.hbaseinfo.c文件拷贝到net-snmp源文件下agent/mibgroup目录下;

2)打开win32sdk,将其添加到netsnmpmibssdk工程;

3)打开net-snmp源文件下win32目录下的mib_module_includes.h,添加:

#include "mibgroup/proba/baseinfo.h"

       4)打开net-snmp源文件下win32目录下的mib_module_inits.h,添加:

                if (should_init("baseinfo")) init_baseinfo();

       5)重新编译netsnmpmibssdk工程和snmpdsdk工程,把生成的snmpd.exe拷贝到c:/usr/binnetsnmpmibs.lib拷贝到c:/usr/lib

四.管理站开发

以获取sysName节点为例:

   struct snmp_session session, *ss;

   struct snmp_pdu *pdu;

   struct snmp_pdu *response;

 

   oid anOID[MAX_OID_LEN];

   size_t anOID_len = MAX_OID_LEN;

  

   struct variable_list *vars;

   int status;

 

   /*

    * Initialize the SNMP library

    */

   init_snmp("snmpapp");

 

    /*

    * Initialize a "session" that defines who we're going to talk to

    */

   snmp_sess_init( &session );                   /* set up defaults */

   session.peername = "localhost";

  

   /* set up the authentication parameters for talking to the server */

  

   #ifdef DEMO_USE_SNMP_VERSION_3

  

   /* Use SNMPv3 to talk to the experimental server */

  

   /* set the SNMP version number */

   session.version=SNMP_VERSION_3;

       

   /* set the SNMPv3 user name */

   session.securityName = strdup("MD5User");

   session.securityNameLen = strlen(session.securityName);

  

   /* set the security level to authenticated, but not encrypted */

   session.securityLevel = SNMP_SEC_LEVEL_AUTHNOPRIV;

  

   /* set the authentication method to MD5 */

   session.securityAuthProto = usmHMACMD5AuthProtocol;

   session.securityAuthProtoLen = sizeof(usmHMACMD5AuthProtocol)/sizeof(oid);

   session.securityAuthKeyLen = USM_AUTH_KU_LEN;

   

   /* set the authentication key to a MD5 hashed version of our

      passphrase "The Net-SNMP Demo Password" (which must be at least 8

      characters long) */

   if (generate_Ku(session.securityAuthProto,

                   session.securityAuthProtoLen,

                   (u_char *) our_v3_passphrase, strlen(our_v3_passphrase),

                   session.securityAuthKey,

                   &session.securityAuthKeyLen) != SNMPERR_SUCCESS) {

       snmp_perror(argv[0]);

       snmp_log(LOG_ERR,

                "Error generating Ku from authentication pass phrase. /n");

       exit(1);

   }

  

   #else /* we'll use the insecure (but simplier) SNMPv1 */

  

   /* set the SNMP version number */

   session.version = SNMP_VERSION_1;

  

   /* set the SNMPv1 community name used for authentication */

   session.community = (u_char*)"public";

   session.community[6] = '/0';

   session.community_len = 6;

  

   #endif /* SNMPv1 */

 

   /* windows32 specific initialization (is a noop on unix) */

   SOCK_STARTUP;

  

   /*

    * Open the session

    */

   ss = snmp_open(&session);                     /* establish the session */

 

   if (!ss) {

       snmp_perror("ack");

       snmp_log(LOG_ERR, "something horrible happened!!!/n");

       exit(2);

   }

 

   /*

    * Create the PDU for the data for our request.

    *   1) We're going to GET the system.sysDescr.0 node.

    */

   pdu = snmp_pdu_create(SNMP_MSG_GET);

 

   read_objid(". 1.3.6 .1.2.1.1.5.0", anOID, &anOID_len);

   //get_node("sysDescr.0", anOID, &anOID_len);

 

   snmp_add_null_var(pdu, anOID, anOID_len);

 

   /*

    * Send the Request out.

    */

   status = snmp_synch_response(ss, pdu, &response);

 

   /*

    * Process the response.

    */

   if (status == STAT_SUCCESS && response->errstat == SNMP_ERR_NOERROR) {

     /*

      * SUCCESS: Print the result variables

      */

     for(vars = response->variables; vars; vars = vars->next_variable)

       print_variable(vars->name, vars->name_length, vars);

     /* manipuate the information ourselves */

     for(vars = response->variables; vars; vars = vars->next_variable) {

       int count=1;

       if (vars->type == ASN_OCTET_STR) {

         char *sp = (char *)malloc(1 + vars->val_len);

         memcpy(sp, vars->val.string, vars->val_len);

         sp[vars->val_len] = '/0';

         printf("value #%d is a string: %s/n", count++, sp);

         free(sp);

       }

       else

         printf("value #%d is NOT a string! Ack!/n", count++);

     }

   } else {

     /*

      * FAILURE: print what went wrong!

      */

   

     if (status == STAT_SUCCESS)

       fprintf(stderr, "Error in packet/nReason: %s/n",

               snmp_errstring(response->errstat));

     else

       snmp_sess_perror("snmpget", ss);

   

   }

 

   /*

    * Clean up:

    *  1) free the response.

    *  2) close the session.

    */

   if (response)

     snmp_free_pdu(response);

   snmp_close(ss);

   

   /* windows32 specific cleanup (is a noop on unix) */

   SOCK_CLEANUP;

  

注意:需要引用以下头文件:

#include

#include

#include

链接netsnmp.lib:

#pragma comment(lib, "netsnmp")

    使用的编译环境为VC++2005.net

需要把netsnmp.lib所在的目录添加到【附加库目录】中,Release版的【代码生成】->【运行时库】选择【多线程 DLL (/MD)】,Debug版选择【多线程调试 DLL (/MDd)】;

Stdafx.h中添加:

#include

    MFC的使用】选择【使用标准 Windows 库】

在编译的过程中发现,不仅要把net-snmp原文件夹下include目录添加到【附加包含目录】,还需要把win32目录也添加进去,因为win32/net-snmp/library下有一个snmpv3-security-includes.h文件。

五.其它注意事项

1.       如果是采用下载可执行文件安装net-snmp时,Net-SNMP Agent Service项选择Standard agent,否则无法从管理器上读取到AgentSystem等节点下的信息。

使用SNMP++提供的一个C#组件。控制面板添加安装组件中添加SNMP组件后,system32目录下会增加许多*.mib文件,如dhcp.mib,这些文件是mib库,存放的是OID与名字和描述的对应关系,相当于DNS。有了这些文件,在SNMP++.net开发包中,调用MIB类的loadDirectoryMib方法,就可以载入这些对应关系了。

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