win32/dist/htmlhelp/Developer_FAQ.html - vendor/opensource/netsnmp - Git at Google

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     <h1>rstory's NET-SNMP Developers Frequently Asked Questions Page</h1>
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 <hr>
     <div align=center>
     <font size=-1>
       <a href="FAQ.html">[Official FAQ]</a> |
 	<a href="#tokens">[Debug tokens]</a> |
 	<a href="#agentx">[AgentX]</a> |
 	<a href="#install">[Install]</a> |
 	<a href="#disable">[Disable]</a> |
 	<a href="#errors">[Errors]</a> |
 	<a href="#bits">[Bits]</a> |
 	<a href="#embedded">[embedded perl]</a> |
 	<a href="#smux">[SMUX]</a> |
 	<a href="#entid">[Enterprise OID]</a> |
 	<a href="#autodeps">[Automatic dependencies]</a> |
 	<a href="#cross">[Cross compiling]</a> |
 	<a href="#static">[Static linking]</a> |
 	<a href="#readfds">[readfds]</a> |
 	<a href="#sharing">[Sharing data]</a> |
 	<a href="man1-mib2c.1.html">[mib2c.array-user.conf]</a> |
 	<a href="#steps">[Baby Steps flow]</a> |
       </font>
     </div>
 <hr>
 This is just a quick page to answer some common questions that aren't covered
 in the <a href="/FAQ.html">official FAQ</a>.

 <a name="agentx"></a> <h2>AgentX</h2>
 <pre> To have the sub-agent communicate on a different socket, or with
 different permissions, add these line to your snmpd.conf

 	# socket path
 	agentxsocket /tmp/agentx

 	# perms socket directory userid groupid
 	agentxperms 777 777 rstory rstory


 and add this line to your subagent:

 	netsnmp_ds_set_string(NETSNMP_DS_APPLICATION_ID, NETSNMP_DS_AGENT_X_SOCKET, "/tmp/agentx");

 *before* you call init_agent().

  </pre>

 <a name="install"></a><h2>install</h2>
 <pre> INSTALL_PREFIX goes before everything.. so, with the defaults, just
 setting INSTALL_PREFIX=/tmp would result in /tmp/usr/local..
 so INSTALL_PREFIX=/tmp prefix=/usr exec_prefix=/usr would go into /tmp/usr
  </pre>

 <a name="disable"></a><h2>disable</h2>
 <pre> If you are using net-snmp Version >= 5.1, then the following configure
 options may be useful to you:

   --disable-agent                 Do not build the agent (snmpd).
   --disable-applications          Do not build the apps (snmpget, ...).
   --disable-manuals               Do not install the manuals.
   --disable-scripts               Do not install the scripts (mib2c, ...).
   --disable-mibs                  Do not install the mib files.
   --disable-mib-loading            Do not include code that parses and
                                    manipulates the mib files.
  </pre>

 <a name="errors"></a><h2>errors</h2>
 <pre> from RFC 3416:

                    noError(0),
                    tooBig(1),
                    noSuchName(2),      -- for proxy compatibility
                    badValue(3),        -- for proxy compatibility
                    readOnly(4),        -- for proxy compatibility
                    genErr(5),
                    noAccess(6),
                    wrongType(7),
                    wrongLength(8),
                    wrongEncoding(9),
                    wrongValue(10),
                    noCreation(11),
                    inconsistentValue(12),
                    resourceUnavailable(13),
                    commitFailed(14),
                    undoFailed(15),
                    authorizationError(16),
                    notWritable(17),
                    inconsistentName(18)
  </pre>

 <a name="bits"></a><h2>bits</h2>
 <pre> SNMPv1 use BIT STRINGs (RFC 1212, 5.1.1):

           (3)  An object with BIT STRING syntax containing no more than
                32 bits becomes an INTEGER defined as a sum; otherwise if
                more than 32 bits are present, the object becomes an
                OCTET STRING, with the bits numbered from left-to-right,
                in which the least significant bits of the last octet may
                be "reserved for future use".

 SNMPv2 and beyond uses BITS (RFC 3417, 8.1):

    (3)   When encoding an object whose syntax is described using the
          BITS construct, the value is encoded as an OCTET STRING, in
          which all the named bits in (the definition of) the bitstring,
          commencing with the first bit and proceeding to the last bit,
          are placed in bits 8 (high order bit) to 1 (low order bit) of
          the first octet, followed by bits 8 to 1 of each subsequent
          octet in turn, followed by as many bits as are needed of the
          final subsequent octet, commencing with bit 8.  Remaining bits,
          if any, of the final octet are set to zero on generation and
          ignored on receipt.
  </pre>

 <a name="embedded"></a> <h2>embedded perl</h2>
 <pre> Add the following line to snmpd.conf:

    perl do "/path/to/perl_module.pl"


 To test:

 1) Try staring up snmpd, like so: 'snmpd -Dperl'. Check your log files for:

   perl: initializing perl (/tmp/snmp_perl.pl)
   starting perl_module.pl
   perl_module.pl loaded ok
   registering at netSnmp.999

 If you get:

   perl: initializing perl (/usr/local/share/snmp/snmp_perl.pl)
   Can't open perl script "/usr/local/share/snmp/snmp_perl.pl": No such file or directory
   embedded perl support failed to initalize

 Then you need to locate snmp_perl.pl, and put it in the correct path, OR put
 the path in your snmpd.conf:

 	perlInitFile /tmp/snmp_perl.pl


 2) Once it's loaded ok, try a walk:

 	snmpwalk -v2c -c public localhost netSnmp.999

 You should see something like this in your logs:

  refs: NetSNMP::agent::netsnmp_mib_handler, NetSNMP::agent::reginfo, NetSNMP::agent::netsnmp_agent_request_info, NetSNMP::agent::netsnmp_request_infoPtr
 processing a request of type 161
    processing request of nsTransactionEntry.3
     .1.3.6.1.4.1.8072.999.1.2.1 -> hello world
    finished processing

 3) If not, maybe check /path/to/perl_module.pl and make sure it is executable.

 Hope that helps.

  </pre>

 <a name="smux"></a> <h2>SMUX</h2>
 <pre> To turn off SMUX when you don't have the options of recompiling from source
 to disable SMUX support, you have to give it an invalid IP address to bind
 to. This may be OS specific. On Linux, if I put this in my snmpd.conf:

 	smuxsocket 1.0.0.0

 I get an error at startup, and lsof or netstat show that snmpd is no longer
 listenting on port 199. If you get and error message about the smuxsocket
 token not being recongnized, then you're out of luck. You'll have to recompile
 from source (or just use local firewall rules to block connections to port
 199).
  </pre>

 <a name="entid"></a> <h2>Enterprise OID</h2>
 <pre> From: Dave Shield, RObert Story

 Recent Versions (5.x)
 ---------------------
 If you want to *just* change the sysObjectID numbering,
 (and leave the notifications using the Net-SNMP enterprise OID)
 then use  --with-enterprise-sysoid
 Or you could just use the snmpd.conf directive 'sysobjectid'
 to set this at run time.


 If you want to *just* change enterprise-specific notification OID
 (and leave the sysObjectID using the Net-SNMP values)
 then use  --with-enterprise-notification-oid


 If you want to change *both* of these,
 then use --with-enterprise-oid

 Older Versions (4.2.x)
 ----------------------
 In older version, you have to manuall update the version_id in
 agent/agent_trap.c:80

    oid version_id[]    = { EXTENSIBLEMIB, AGENTID, OSTYPE };

  </pre>

 <a name="autodeps"></a> <h2>Automatic dependencies</h2>
 <pre> For auto-dependencies, add the following to your Makefile:

 #
 # Build rules
 #
 %.d : %.c
 	@echo "Generating makefile $@ ..."
 	@set -e; $(CC) -M $(COPTS) $(CFLAGS) $(CPPFLAGS) $< \
 	| sed 's/\($*\)\.o[ :]*/\1.o $@ : /g' > $@; \
 	[ -s $@ ] || $(RM) $(RMFLAGS) $@

 include $(SOURCES:.c=.d)

  </pre>

 <a name="cross"></a> <h2>Cross compiling</h2>
 <pre> From the net-snmp INSTALL file:

  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

 Specifying the System Type
 ==========================

    There may be some features `configure' can not figure out
 automatically, but needs to determine by the type of host the package
 will run on.  Usually `configure' can figure that out, but if it prints
 a message saying it can not guess the host type, give it the
 `--host=TYPE' option.  TYPE can either be a short name for the system
 type, such as `sun4', or a canonical name with three fields:
      CPU-COMPANY-SYSTEM

 See the file `config.sub' for the possible values of each field.  If
 `config.sub' isn't included in this package, then this package doesn't
 need to know the host type.

    If you are building compiler tools for cross-compiling, you can also
 use the `--target=TYPE' option to select the type of system they will
 produce code for and the `--build=TYPE' option to select the type of
 system on which you are compiling the package.

  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

 The most important configure options are:

 	--with-cc=[cross-compiler]
 	--with-ld=[cross-linker]
 	--target=[target-environment]
 	--with-endianness=[big|little]

 Other potentially useful options:

 	--with-cflags="..."
 	--with-ldlags="..."
 	--with-ar=/path/ar

 	--enable-mini-agent
 	--enable-shared="no"
 	--without-pic

 Two simple examples of cross-compiling:

 ./configure --target=ppc-linux --with-cc=ppc_405-gcc --with-endianness=big

 ./configure --target=powerpc-snmc-linux-gnu --build=i386-redhat-linux \
         --with-endianness=big

 A more complex example involves setting environment variables for all
 the flags for the tools needed for the cross compile:

    export TOOLPATH=/opt/hardhat/devkit/ppc/405
    export PATH=$TOOLPATH/bin:$PATH
    export CFLAGS=' -g -fPIC -msoft-float -D_SOFT_FLOAT -Dlinux -mcpu=403'
    export CPPFLAGS='-I$TOOLPATH/include -I$TOOLPATH/target/usr/include'
    export ASFLAGS='-g -gstabs'
    export LDFLAGS='-Wl,-soname,-Bdynamic -lc'
    export LIB='ar rcu'

    ./configure --build=i686-pc-linux-gnu  --host=powerpc \
            --target=powerpc-hardhat-linux-gnu --with-endianness=big


  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

 The mibgroup section is the most OS specific part of the agent. It's likely
 that you will have to remove some of them. You just need to figure out which
 ones to remove.

 For example, agent/mibgroup/mibII/tcpTable.c is a common module that doesn't
 work on new platforms. So if it isn't working, omit it during configure, like
 so:

 	./configure --with-out-mib-modules=mibII/tcpTable


 Alternatively, you could work the other way. Start with a minimal
 configuration:

 	./configure --enable-mini-agent

 and then start adding MIB modules one-by-one:

 	./configure --enable-mini-agent
                     --with-mib-modules=mibII/system_mib,mibII/sysORTable


  </pre>

 <a name="static"></a> <h2>Static linking</h2>
 <pre> mXaureliu: I want to compile the 5.1 snmptrapd binary with statically linked libraries.. Can anyone help me with this? Is it just a simple configure switch
 rstory: mXaureliu: you want static snmp libraries, or totally static (system libraries too)?
 mXaureliu: totally static.. everything in one executable
 mXaureliu: actually, how do i do both ways?
 rstory: for snmp libs, try 'configure --enable-shared=no'.. that won't build the shared libraries
 rstory: (though if you have previous versions of net-snmp libraries installed, the linker might pick those up and try and use them)
 rstory: for totally static, you'll have to tweak the Makefile
 rstory: add -Bstatic to LDFLAGS

 [note: actually, for totally static, 'configure --with-ldflags=-Bstatic']
  </pre>

 <a name="readfds"></a> <h2>readfds</h2>
 <pre> > can you please tell me the meaning of the third argument. obviously the
 > first parameter to register_readfd is a file descriptor and second is the
 > callback function.

 Correct.
 The third parameter is arbitrary data that you can specify when you
 register the file descriptor, and will then be passed to the callback
 function when it's invoked.


 So if you were listening on two separate sockets, for very similar
 types of data, then you could use the same callback for both and
 use this third parameter to distinguish between them:


 	fd1 = open( "/proc/tweedledum" );
 	fd2 = open( "/proc/tweedledee" );

 	register_readfd( fd1, who_broke_the_rattle(), "tweedledee" );
 	register_readfd( fd2, who_broke_the_rattle(), "tweedledum" );


 void
 who_broke_the_rattle( int fd, void *data )
 {
     char *he_did = (char *)data;

     printf("%s broke the rattle!\n", he_did );
 }

  </pre>

 <a name="sharing"></a> <h2>sharing data</h2>
 <pre> If two modules are compiled into the same agent/subagent, then just use a
 normal C global var. No need to involve net-snmp in the process.

 if they are different sub-agents, you are better off using tradition IPC
 mechanisms. there is no net-snmp api for sharing data between subagents.

 That said, *IF* you only need the data during processing of GET requests, or
 when you aren't processing a request at all, you send a snmp request to the
 master, which will query the other subagent. If you are processing a GET
 request and are compiled into the master, you will have to delegate the
 current request).

 It's a little inefficient, compared to direct communication w/the other
 subagent and it *will not* work during set processing.
  </pre>

 <a name="tokens"></a> <h2>Debug Tokens</h2>
 <pre> Some of the more common ones are:

    Agent: agent, agentx, dlmod, handler, helper, snmpd, trap, table
    MIBs: init_mib, mib_init, parse-file, parse-mibs
    Apps: read_config

 Add them to your snmp.conf like so:

    # optionally turn on time stamps
    logTimestamp true
    doDebugging 1
    debugTokens agentx/config

 If you put them in a different conf file, like snmpd.conf or myapp.conf,
 prefix each with '[snmp]', like so:

    [snmp] doDebugging 1


 This list was generated by running the following command in the main CVS branch:

 find . -name \"*.c\" -print | xargs grep DEBUGMSGT | grep \" | cut -f 2 -d\" | sort -u

 add
 agent_handler
 agent_registry
 agent_set
 agentx
 agentx_build
 agentx_build_varbind
 agentx/config
 agentx/config/retries
 agentx/config/timeout
 agentx/master
 agentx/subagent
 agentx/subgaent
 asn_realloc
 auto_nlist
 build_oid_noalloc
 build_oid_segment
 callback
 callback_clear
 check_getnext_results
 clear_nsap_list
 compare:index
 comparex
 container
 container_iterator
 container_iterator:results
 container:null:
 container:null:find
 container:null:find_next
 container:null:for_each
 container:null:free
 container:null:get_null
 container:null:get_null_factory
 container:null:get_null_noalloc
 container:null:insert
 container:null:remove
 container:null:size
 container_registry
 daemonize
 deinit_usm_post_config
 delayed_instance
 dlmod
 dump_etimelist
 encode_keychange
 example
 example_data_set
 example_notification
 example_scalar_int
 fixup_mib_directory
 generate_Ku
 generate_kul
 get_mib_directory
 handler:calling
 handler:inject
 handler::register
 handler_registry
 handler:returned
 header_complex
 header_complex_add_data
 header_complex_dump
 header_complex_extract_entry
 header_complex_generate_oid
 header_complex_generate_varoid
 header_complex_parse_oid
 header_complex_test
 helper:baby_steps
 helper:cache_handler
 helper:debug
 helper:instance
 helper:mfd
 helper:null
 helper:read_only
 helper:row_merge
 helper:scalar
 helper:scalar_group
 helper:serialize
 helper:stash_cache
 helper:table
 helper:watcher
 helper:watcher:spinlock
 helper:watcher:timestamp
 host/hr_device
 host/hr_disk
 host/hr_filesys
 host/hr_inst
 host/hr_network
 host/hr_partition
 host/hr_print
 host/hr_proc
 host/hr_storage
 host/hr_swinst
 host/hr_swrun
 host/hr_swrun::GetNextHR_SWRun
 host/hr_system
 hr_proc
 initialize_table_ipCidrRouteTable
 initialize_table_mteEventNotificationTable
 initialize_table_mteEventTable
 initialize_table_netSnmpHostsTable
 initialize_table_nlmLogTable
 initialize_table_nlmLogVariableTable
 initialize_table_nsModuleTable
 initialize_table_nsTransactionTable
 init_mib
 init_usm
 injectHandler
 kernel_sunos5
 ksm
 lcd_get_enginetime
 lcd_get_enginetime_ex
 lcd_set_enginetime
 log_notification
 md5
 mfd
 mibII/at
 mibII/icmp
 mibII/interfaces
 mibII/ip
 mibII/ipv6
 mibII/mta_sendmail.c:mta_sendmail_parse_config
 mibII/mta_sendmail.c:open_sendmailst
 mibII/mta_sendmail.c:read_sendmailcf
 mibII/snmp_mib
 mibII/sysORTable
 mibII/tcpScalar
 mibII/tcpTable
 mibII/udpScalar
 mibII/udpTable
 mibII/vacm_vars
 mibII/var_route
 mib_init
 mte_disco
 mteEventTable:send_events
 mteObjectsTable
 mteTriggerBooleanTable
 mteTriggerDeltaTable
 mteTriggerExistenceTable
 mteTriggertable
 mteTriggerTable
 mteTriggerTest
 mteTriggerTest:send_mte_trap
 mteTriggerThresholdTable
 netsnmp_aal5pvc
 netsnmp_agent_check_packet
 netsnmp_deregister_agent_nsap
 netsnmp_ds_handle_config
 netsnmp_ds_set_boolean
 netsnmp_ds_set_int
 netsnmp_ds_set_string
 netsnmp_ds_set_void
 netsnmp_ds_toggle_boolean
 netsnmp_instance_counter32_handler
 netsnmp_instance_int_handler
 netsnmp_instance_long_handler
 netsnmp_instance_ulong_handler
 netsnmp_ipx
 netsnmp_register_agent_nsap
 netsnmp_register_mib_table_row
 netsnmp_sockaddr_in
 netsnmp_sockaddr_in6
 netsnmp_sockaddr_ipx
 netsnmp_table_data_set
 netsnmp_tcp
 netsnmp_tcp6
 netsnmp_udp
 netsnmp_udp6
 netsnmp_udp6_getSecName
 netsnmp_udp6_parse_security
 netsnmp_udp_getSecName
 netsnmp_udp_parse_security
 netsnmp_unix
 netsnmp_unix_getSecName
 netsnmp_unix_parse_security
 netsnmp_unix_transport
 netstat:if
 notification_log
 nsCacheScalars
 nsDebugScalars
 object_monitor
 old_api
 output
 override
 parse-file
 parse-mibs
 parse_oid
 parse_oid_indexes
 perl
 proc
 proxy
 proxy_args
 proxy_config
 proxy_init
 read_config
 read_config_copy_word
 read_config_files
 read_config:forward
 read_config:initmib
 read_config_read_data
 read_config_read_memory
 read_config_read_objid
 read_config_read_octet_string
 read_config_store_data_prefix
 read_config:traphandle
 register_exceptfd
 register_index
 register_mib
 register_readfd
 register_signal
 register_writefd
 report
 results
 scalar_int
 scapi
 scopedPDU_parse
 send_notifications
 sess_async_send
 _sess_open
 sess_process_packet
 sess_read
 sess_resend
 sess_select
 setting auth type: \
 signal
 smux
 smux_conf
 smux_init
 smux/snmp_bgp
 smux/snmp_ospf
 smux/snmp_rip2
 snmp_agent
 snmp_alarm
 snmp_api
 snmp_build
 snmp_clean_persistent
 snmp_config
 snmpd
 snmpd/main
 snmpd_ports
 snmpd_register_app_config_handler
 snmpd/select
 snmpEngine
 snmpNotifyFilterProfileTable
 snmpNotifyFilterTable
 snmpNotifyTable
 snmp_parse
 snmp_parse_args
 snmp_parse_oid
 snmp_pdu_realloc_rbuild
 snmp_save_persistent
 snmp_send
 snmp_sess_add
 snmp_sess_close
 snmp_sess_open
 snmpSetSerialNo
 snmp_store
 snmpTargetAddrEntry
 snmpTargetParamsEntry
 snmptrapd
 snmpv3
 snmpv3_parse
 sprint_by_type
 stash_cache
 subtree
 table_array
 table_array:get
 table_array:group
 table_data_add_data
 table_iterator
 table_set_add_row
 take_snapshot
 target_counters
 target_sessions
 tdomain
 testhandler
 testhandler_table
 transport_callback
 trap
 trapsess
 tunnel
 ucdDemoPublic
 ucd-snmp/disk
 ucd-snmp/disk:
 ucd-snmp/memory
 ucd-snmp/pass
 ucd-snmp/pass_persist
 ucd-snmp/proc
 ucd-snmp/versioninfo
 ucd-snmp/vmstat_aix4.c:update_stats
 ucd-snmp/vmstat_dynix.c:update_stats
 ucd-snmp/vmstat_hpux.c:update_stats
 ucd-snmp/vmstat_solaris2.c:update_stats
 unlink_tree
 unload-mib
 unregister_exceptfd
 unregister_readfd
 unregister_signal
 unregister_writefd
 usm
 usmUser
 util_funcs
 vacm:checkSubtree
 vacm:getView
 versioninfo
 vmstat
 yyyinjectHandler
  </pre>

 <a name="steps"></a> <h2>Baby Steps Flow</h2>
 <pre>     /**
      * Baby Steps Flow diagram (rev 2003.09.29.1330)
      *
      * Legend: (test) [optional] &lt;required>
      *
      * OLD              NEW
      * ========  ============================================
      * +++           [pre_request]
      *                    |
      *               (row exists?) N ->(row_creation) N >-->+
      *                    |                   | Y           |
      *                    |&lt;------------------+             |
      *                   \|/                               \|/
      * RESERVE1  &lt;object_syntax_checks>                     |
      *                    |                                 |
      *                  (err?)  Y >------------------------>+
      *                    |                                 |
      *                   \|/                               \|/
      * +++          (row existed?) N --->[row_creation]     |
      *                    |                   |             |
      *                    |&lt;--------------N (err?)          |
      *                    |                   | Y           |
      *                    |                   |             |
      *                    |       [row_creation_cleanup]--->+
      *                   \|/                                |
      * RESERVER2     [undo_setup]                           |
      *                    |                                 |
      *                  (err?)  Y --->-------->--------->+  |
      *                    |                              | \|/
      * ACTION        &lt;set_values>                        |  |
      *                    |                              |  |
      *                  (err?)  Y >---------+           \|/ |
      *                    |                 |            |  |
      * +++        [consistency_checks]      |            |  |
      *                    |                \|/           |  |
      * UNDO             (err?)  Y >-------[undo]-------->+  |
      *                    |                              |  |
      *            [reversible_commit]                    |  |
      * +++                |                              | \|/
      *                  (err?)  Y >--[reverse_commit]    |  |
      *                    |              |               |  |
      * COMMIT        &lt;final_commit>      |               |  |
      *                    |              |               |  |
      *                  (err?)  Y >--[log msg]           |  |
      *                    |              |               |  |
      *                    |             \|/             \|/ |
      *                    | &lt;-----------&lt;+---&lt;-----------+  |
      *                   \|/                                |
      * FREE          [undo_cleanup]                         |
      *                    |                                \|/
      *                    |&lt;--------------&lt;-----------------+
      *                   \|/
      *               [post_request]
      */
  </pre>

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	<h1>rstory's NET-SNMP Developers Frequently Asked Questions Page</h1>
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	<font size=-1>
	<a href="FAQ.html">[Official FAQ]</a> \|
	<a href="#tokens">[Debug tokens]</a> \|
	<a href="#agentx">[AgentX]</a> \|
	<a href="#install">[Install]</a> \|
	<a href="#disable">[Disable]</a> \|
	<a href="#errors">[Errors]</a> \|
	<a href="#bits">[Bits]</a> \|
	<a href="#embedded">[embedded perl]</a> \|
	<a href="#smux">[SMUX]</a> \|
	<a href="#entid">[Enterprise OID]</a> \|
	<a href="#autodeps">[Automatic dependencies]</a> \|
	<a href="#cross">[Cross compiling]</a> \|
	<a href="#static">[Static linking]</a> \|
	<a href="#readfds">[readfds]</a> \|
	<a href="#sharing">[Sharing data]</a> \|
	<a href="man1-mib2c.1.html">[mib2c.array-user.conf]</a> \|
	<a href="#steps">[Baby Steps flow]</a> \|
	</font>
	</div>
	<hr>
	This is just a quick page to answer some common questions that aren't covered
	in the <a href="/FAQ.html">official FAQ</a>.

	<a name="agentx"></a> <h2>AgentX</h2>
	<pre> To have the sub-agent communicate on a different socket, or with
	different permissions, add these line to your snmpd.conf

	# socket path
	agentxsocket /tmp/agentx

	# perms socket directory userid groupid
	agentxperms 777 777 rstory rstory


	and add this line to your subagent:

	netsnmp_ds_set_string(NETSNMP_DS_APPLICATION_ID, NETSNMP_DS_AGENT_X_SOCKET, "/tmp/agentx");

	before you call init_agent().

	</pre>

	<a name="install"></a><h2>install</h2>
	<pre> INSTALL_PREFIX goes before everything.. so, with the defaults, just
	setting INSTALL_PREFIX=/tmp would result in /tmp/usr/local..
	so INSTALL_PREFIX=/tmp prefix=/usr exec_prefix=/usr would go into /tmp/usr
	</pre>

	<a name="disable"></a><h2>disable</h2>
	<pre> If you are using net-snmp Version >= 5.1, then the following configure
	options may be useful to you:

	--disable-agent Do not build the agent (snmpd).
	--disable-applications Do not build the apps (snmpget, ...).
	--disable-manuals Do not install the manuals.
	--disable-scripts Do not install the scripts (mib2c, ...).
	--disable-mibs Do not install the mib files.
	--disable-mib-loading Do not include code that parses and
	manipulates the mib files.
	</pre>

	<a name="errors"></a><h2>errors</h2>
	<pre> from RFC 3416:

	noError(0),
	tooBig(1),
	noSuchName(2), -- for proxy compatibility
	badValue(3), -- for proxy compatibility
	readOnly(4), -- for proxy compatibility
	genErr(5),
	noAccess(6),
	wrongType(7),
	wrongLength(8),
	wrongEncoding(9),
	wrongValue(10),
	noCreation(11),
	inconsistentValue(12),
	resourceUnavailable(13),
	commitFailed(14),
	undoFailed(15),
	authorizationError(16),
	notWritable(17),
	inconsistentName(18)
	</pre>

	<a name="bits"></a><h2>bits</h2>
	<pre> SNMPv1 use BIT STRINGs (RFC 1212, 5.1.1):

	(3) An object with BIT STRING syntax containing no more than
	32 bits becomes an INTEGER defined as a sum; otherwise if
	more than 32 bits are present, the object becomes an
	OCTET STRING, with the bits numbered from left-to-right,
	in which the least significant bits of the last octet may
	be "reserved for future use".

	SNMPv2 and beyond uses BITS (RFC 3417, 8.1):

	(3) When encoding an object whose syntax is described using the
	BITS construct, the value is encoded as an OCTET STRING, in
	which all the named bits in (the definition of) the bitstring,
	commencing with the first bit and proceeding to the last bit,
	are placed in bits 8 (high order bit) to 1 (low order bit) of
	the first octet, followed by bits 8 to 1 of each subsequent
	octet in turn, followed by as many bits as are needed of the
	final subsequent octet, commencing with bit 8. Remaining bits,
	if any, of the final octet are set to zero on generation and
	ignored on receipt.
	</pre>

	<a name="embedded"></a> <h2>embedded perl</h2>
	<pre> Add the following line to snmpd.conf:

	perl do "/path/to/perl_module.pl"


	To test:

	1) Try staring up snmpd, like so: 'snmpd -Dperl'. Check your log files for:

	perl: initializing perl (/tmp/snmp_perl.pl)
	starting perl_module.pl
	perl_module.pl loaded ok
	registering at netSnmp.999

	If you get:

	perl: initializing perl (/usr/local/share/snmp/snmp_perl.pl)
	Can't open perl script "/usr/local/share/snmp/snmp_perl.pl": No such file or directory
	embedded perl support failed to initalize

	Then you need to locate snmp_perl.pl, and put it in the correct path, OR put
	the path in your snmpd.conf:

	perlInitFile /tmp/snmp_perl.pl


	2) Once it's loaded ok, try a walk:

	snmpwalk -v2c -c public localhost netSnmp.999

	You should see something like this in your logs:

	refs: NetSNMP::agent::netsnmp_mib_handler, NetSNMP::agent::reginfo, NetSNMP::agent::netsnmp_agent_request_info, NetSNMP::agent::netsnmp_request_infoPtr
	processing a request of type 161
	processing request of nsTransactionEntry.3
	.1.3.6.1.4.1.8072.999.1.2.1 -> hello world
	finished processing

	3) If not, maybe check /path/to/perl_module.pl and make sure it is executable.

	Hope that helps.

	</pre>

	<a name="smux"></a> <h2>SMUX</h2>
	<pre> To turn off SMUX when you don't have the options of recompiling from source
	to disable SMUX support, you have to give it an invalid IP address to bind
	to. This may be OS specific. On Linux, if I put this in my snmpd.conf:

	smuxsocket 1.0.0.0

	I get an error at startup, and lsof or netstat show that snmpd is no longer
	listenting on port 199. If you get and error message about the smuxsocket
	token not being recongnized, then you're out of luck. You'll have to recompile
	from source (or just use local firewall rules to block connections to port
	199).
	</pre>

	<a name="entid"></a> <h2>Enterprise OID</h2>
	<pre> From: Dave Shield, RObert Story

	Recent Versions (5.x)
	---------------------
	If you want to just change the sysObjectID numbering,
	(and leave the notifications using the Net-SNMP enterprise OID)
	then use --with-enterprise-sysoid
	Or you could just use the snmpd.conf directive 'sysobjectid'
	to set this at run time.


	If you want to just change enterprise-specific notification OID
	(and leave the sysObjectID using the Net-SNMP values)
	then use --with-enterprise-notification-oid


	If you want to change both of these,
	then use --with-enterprise-oid

	Older Versions (4.2.x)
	----------------------
	In older version, you have to manuall update the version_id in
	agent/agent_trap.c:80

	oid version_id[] = { EXTENSIBLEMIB, AGENTID, OSTYPE };

	</pre>

	<a name="autodeps"></a> <h2>Automatic dependencies</h2>
	<pre> For auto-dependencies, add the following to your Makefile:

	#
	# Build rules
	#
	%.d : %.c
	@echo "Generating makefile $@ ..."
	@set -e; $(CC) -M $(COPTS) $(CFLAGS) $(CPPFLAGS) $< \
	\| sed 's/\($\)\.o[ :]/\1.o $@ : /g' > $@; \
	[ -s $@ ] \|\| $(RM) $(RMFLAGS) $@

	include $(SOURCES:.c=.d)

	</pre>

	<a name="cross"></a> <h2>Cross compiling</h2>
	<pre> From the net-snmp INSTALL file:

	- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

	Specifying the System Type
	==========================

	There may be some features `configure' can not figure out
	automatically, but needs to determine by the type of host the package
	will run on. Usually `configure' can figure that out, but if it prints
	a message saying it can not guess the host type, give it the
	`--host=TYPE' option. TYPE can either be a short name for the system
	type, such as `sun4', or a canonical name with three fields:
	CPU-COMPANY-SYSTEM

	See the file `config.sub' for the possible values of each field. If
	`config.sub' isn't included in this package, then this package doesn't
	need to know the host type.

	If you are building compiler tools for cross-compiling, you can also
	use the `--target=TYPE' option to select the type of system they will
	produce code for and the `--build=TYPE' option to select the type of
	system on which you are compiling the package.

	- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

	The most important configure options are:

	--with-cc=[cross-compiler]
	--with-ld=[cross-linker]
	--target=[target-environment]
	--with-endianness=[big\|little]

	Other potentially useful options:

	--with-cflags="..."
	--with-ldlags="..."
	--with-ar=/path/ar

	--enable-mini-agent
	--enable-shared="no"
	--without-pic

	Two simple examples of cross-compiling:

	./configure --target=ppc-linux --with-cc=ppc_405-gcc --with-endianness=big

	./configure --target=powerpc-snmc-linux-gnu --build=i386-redhat-linux \
	--with-endianness=big

	A more complex example involves setting environment variables for all
	the flags for the tools needed for the cross compile:

	export TOOLPATH=/opt/hardhat/devkit/ppc/405
	export PATH=$TOOLPATH/bin:$PATH
	export CFLAGS=' -g -fPIC -msoft-float -D_SOFT_FLOAT -Dlinux -mcpu=403'
	export CPPFLAGS='-I$TOOLPATH/include -I$TOOLPATH/target/usr/include'
	export ASFLAGS='-g -gstabs'
	export LDFLAGS='-Wl,-soname,-Bdynamic -lc'
	export LIB='ar rcu'

	./configure --build=i686-pc-linux-gnu --host=powerpc \
	--target=powerpc-hardhat-linux-gnu --with-endianness=big



	- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

	The mibgroup section is the most OS specific part of the agent. It's likely
	that you will have to remove some of them. You just need to figure out which
	ones to remove.

	For example, agent/mibgroup/mibII/tcpTable.c is a common module that doesn't
	work on new platforms. So if it isn't working, omit it during configure, like
	so:

	./configure --with-out-mib-modules=mibII/tcpTable


	Alternatively, you could work the other way. Start with a minimal
	configuration:

	./configure --enable-mini-agent

	and then start adding MIB modules one-by-one:

	./configure --enable-mini-agent
	--with-mib-modules=mibII/system_mib,mibII/sysORTable


	</pre>

	<a name="static"></a> <h2>Static linking</h2>
	<pre> mXaureliu: I want to compile the 5.1 snmptrapd binary with statically linked libraries.. Can anyone help me with this? Is it just a simple configure switch
	rstory: mXaureliu: you want static snmp libraries, or totally static (system libraries too)?
	mXaureliu: totally static.. everything in one executable
	mXaureliu: actually, how do i do both ways?
	rstory: for snmp libs, try 'configure --enable-shared=no'.. that won't build the shared libraries
	rstory: (though if you have previous versions of net-snmp libraries installed, the linker might pick those up and try and use them)
	rstory: for totally static, you'll have to tweak the Makefile
	rstory: add -Bstatic to LDFLAGS

	[note: actually, for totally static, 'configure --with-ldflags=-Bstatic']
	</pre>

	<a name="readfds"></a> <h2>readfds</h2>
	<pre> > can you please tell me the meaning of the third argument. obviously the
	> first parameter to register_readfd is a file descriptor and second is the
	> callback function.

	Correct.
	The third parameter is arbitrary data that you can specify when you
	register the file descriptor, and will then be passed to the callback
	function when it's invoked.


	So if you were listening on two separate sockets, for very similar
	types of data, then you could use the same callback for both and
	use this third parameter to distinguish between them:


	fd1 = open( "/proc/tweedledum" );
	fd2 = open( "/proc/tweedledee" );

	register_readfd( fd1, who_broke_the_rattle(), "tweedledee" );
	register_readfd( fd2, who_broke_the_rattle(), "tweedledum" );


	void
	who_broke_the_rattle( int fd, void *data )
	{
	char he_did = (char )data;

	printf("%s broke the rattle!\n", he_did );
	}

	</pre>

	<a name="sharing"></a> <h2>sharing data</h2>
	<pre> If two modules are compiled into the same agent/subagent, then just use a
	normal C global var. No need to involve net-snmp in the process.

	if they are different sub-agents, you are better off using tradition IPC
	mechanisms. there is no net-snmp api for sharing data between subagents.

	That said, IF you only need the data during processing of GET requests, or
	when you aren't processing a request at all, you send a snmp request to the
	master, which will query the other subagent. If you are processing a GET
	request and are compiled into the master, you will have to delegate the
	current request).

	It's a little inefficient, compared to direct communication w/the other
	subagent and it will not work during set processing.
	</pre>

	<a name="tokens"></a> <h2>Debug Tokens</h2>
	<pre> Some of the more common ones are:

	Agent: agent, agentx, dlmod, handler, helper, snmpd, trap, table
	MIBs: init_mib, mib_init, parse-file, parse-mibs
	Apps: read_config

	Add them to your snmp.conf like so:

	# optionally turn on time stamps
	logTimestamp true
	doDebugging 1
	debugTokens agentx/config

	If you put them in a different conf file, like snmpd.conf or myapp.conf,
	prefix each with '[snmp]', like so:

	[snmp] doDebugging 1


	This list was generated by running the following command in the main CVS branch:

	find . -name \"*.c\" -print \| xargs grep DEBUGMSGT \| grep \" \| cut -f 2 -d\" \| sort -u

	add
	agent_handler
	agent_registry
	agent_set
	agentx
	agentx_build
	agentx_build_varbind
	agentx/config
	agentx/config/retries
	agentx/config/timeout
	agentx/master
	agentx/subagent
	agentx/subgaent
	asn_realloc
	auto_nlist
	build_oid_noalloc
	build_oid_segment
	callback
	callback_clear
	check_getnext_results
	clear_nsap_list
	compare:index
	comparex
	container
	container_iterator
	container_iterator:results
	container:null:
	container:null:find
	container:null:find_next
	container:null:for_each
	container:null:free
	container:null:get_null
	container:null:get_null_factory
	container:null:get_null_noalloc
	container:null:insert
	container:null:remove
	container:null:size
	container_registry
	daemonize
	deinit_usm_post_config
	delayed_instance
	dlmod
	dump_etimelist
	encode_keychange
	example
	example_data_set
	example_notification
	example_scalar_int
	fixup_mib_directory
	generate_Ku
	generate_kul
	get_mib_directory
	handler:calling
	handler:inject
	handler::register
	handler_registry
	handler:returned
	header_complex
	header_complex_add_data
	header_complex_dump
	header_complex_extract_entry
	header_complex_generate_oid
	header_complex_generate_varoid
	header_complex_parse_oid
	header_complex_test
	helper:baby_steps
	helper:cache_handler
	helper:debug
	helper:instance
	helper:mfd
	helper:null
	helper:read_only
	helper:row_merge
	helper:scalar
	helper:scalar_group
	helper:serialize
	helper:stash_cache
	helper:table
	helper:watcher
	helper:watcher:spinlock
	helper:watcher:timestamp
	host/hr_device
	host/hr_disk
	host/hr_filesys
	host/hr_inst
	host/hr_network
	host/hr_partition
	host/hr_print
	host/hr_proc
	host/hr_storage
	host/hr_swinst
	host/hr_swrun
	host/hr_swrun::GetNextHR_SWRun
	host/hr_system
	hr_proc
	initialize_table_ipCidrRouteTable
	initialize_table_mteEventNotificationTable
	initialize_table_mteEventTable
	initialize_table_netSnmpHostsTable
	initialize_table_nlmLogTable
	initialize_table_nlmLogVariableTable
	initialize_table_nsModuleTable
	initialize_table_nsTransactionTable
	init_mib
	init_usm
	injectHandler
	kernel_sunos5
	ksm
	lcd_get_enginetime
	lcd_get_enginetime_ex
	lcd_set_enginetime
	log_notification
	md5
	mfd
	mibII/at
	mibII/icmp
	mibII/interfaces
	mibII/ip
	mibII/ipv6
	mibII/mta_sendmail.c:mta_sendmail_parse_config
	mibII/mta_sendmail.c:open_sendmailst
	mibII/mta_sendmail.c:read_sendmailcf
	mibII/snmp_mib
	mibII/sysORTable
	mibII/tcpScalar
	mibII/tcpTable
	mibII/udpScalar
	mibII/udpTable
	mibII/vacm_vars
	mibII/var_route
	mib_init
	mte_disco
	mteEventTable:send_events
	mteObjectsTable
	mteTriggerBooleanTable
	mteTriggerDeltaTable
	mteTriggerExistenceTable
	mteTriggertable
	mteTriggerTable
	mteTriggerTest
	mteTriggerTest:send_mte_trap
	mteTriggerThresholdTable
	netsnmp_aal5pvc
	netsnmp_agent_check_packet
	netsnmp_deregister_agent_nsap
	netsnmp_ds_handle_config
	netsnmp_ds_set_boolean
	netsnmp_ds_set_int
	netsnmp_ds_set_string
	netsnmp_ds_set_void
	netsnmp_ds_toggle_boolean
	netsnmp_instance_counter32_handler
	netsnmp_instance_int_handler
	netsnmp_instance_long_handler
	netsnmp_instance_ulong_handler
	netsnmp_ipx
	netsnmp_register_agent_nsap
	netsnmp_register_mib_table_row
	netsnmp_sockaddr_in
	netsnmp_sockaddr_in6
	netsnmp_sockaddr_ipx
	netsnmp_table_data_set
	netsnmp_tcp
	netsnmp_tcp6
	netsnmp_udp
	netsnmp_udp6
	netsnmp_udp6_getSecName
	netsnmp_udp6_parse_security
	netsnmp_udp_getSecName
	netsnmp_udp_parse_security
	netsnmp_unix
	netsnmp_unix_getSecName
	netsnmp_unix_parse_security
	netsnmp_unix_transport
	netstat:if
	notification_log
	nsCacheScalars
	nsDebugScalars
	object_monitor
	old_api
	output
	override
	parse-file
	parse-mibs
	parse_oid
	parse_oid_indexes
	perl
	proc
	proxy
	proxy_args
	proxy_config
	proxy_init
	read_config
	read_config_copy_word
	read_config_files
	read_config:forward
	read_config:initmib
	read_config_read_data
	read_config_read_memory
	read_config_read_objid
	read_config_read_octet_string
	read_config_store_data_prefix
	read_config:traphandle
	register_exceptfd
	register_index
	register_mib
	register_readfd
	register_signal
	register_writefd
	report
	results
	scalar_int
	scapi
	scopedPDU_parse
	send_notifications
	sess_async_send
	_sess_open
	sess_process_packet
	sess_read
	sess_resend
	sess_select
	setting auth type: \
	signal
	smux
	smux_conf
	smux_init
	smux/snmp_bgp
	smux/snmp_ospf
	smux/snmp_rip2
	snmp_agent
	snmp_alarm
	snmp_api
	snmp_build
	snmp_clean_persistent
	snmp_config
	snmpd
	snmpd/main
	snmpd_ports
	snmpd_register_app_config_handler
	snmpd/select
	snmpEngine
	snmpNotifyFilterProfileTable
	snmpNotifyFilterTable
	snmpNotifyTable
	snmp_parse
	snmp_parse_args
	snmp_parse_oid
	snmp_pdu_realloc_rbuild
	snmp_save_persistent
	snmp_send
	snmp_sess_add
	snmp_sess_close
	snmp_sess_open
	snmpSetSerialNo
	snmp_store
	snmpTargetAddrEntry
	snmpTargetParamsEntry
	snmptrapd
	snmpv3
	snmpv3_parse
	sprint_by_type
	stash_cache
	subtree
	table_array
	table_array:get
	table_array:group
	table_data_add_data
	table_iterator
	table_set_add_row
	take_snapshot
	target_counters
	target_sessions
	tdomain
	testhandler
	testhandler_table
	transport_callback
	trap
	trapsess
	tunnel
	ucdDemoPublic
	ucd-snmp/disk
	ucd-snmp/disk:
	ucd-snmp/memory
	ucd-snmp/pass
	ucd-snmp/pass_persist
	ucd-snmp/proc
	ucd-snmp/versioninfo
	ucd-snmp/vmstat_aix4.c:update_stats
	ucd-snmp/vmstat_dynix.c:update_stats
	ucd-snmp/vmstat_hpux.c:update_stats
	ucd-snmp/vmstat_solaris2.c:update_stats
	unlink_tree
	unload-mib
	unregister_exceptfd
	unregister_readfd
	unregister_signal
	unregister_writefd
	usm
	usmUser
	util_funcs
	vacm:checkSubtree
	vacm:getView
	versioninfo
	vmstat
	yyyinjectHandler
	</pre>

	<a name="steps"></a> <h2>Baby Steps Flow</h2>
	<pre> /**
	* Baby Steps Flow diagram (rev 2003.09.29.1330)
	*
	* Legend: (test) [optional] <required>
	*
	* OLD NEW
	* ======== ============================================
	* +++ [pre_request]
	* \|
	* (row exists?) N ->(row_creation) N >-->+
	* \| \| Y \|
	* \|<------------------+ \|
	* \\|/ \\|/
	* RESERVE1 <object_syntax_checks> \|
	* \| \|
	* (err?) Y >------------------------>+
	* \| \|
	* \\|/ \\|/
	* +++ (row existed?) N --->[row_creation] \|
	* \| \| \|
	* \|<--------------N (err?) \|
	* \| \| Y \|
	* \| \| \|
	* \| [row_creation_cleanup]--->+
	* \\|/ \|
	* RESERVER2 [undo_setup] \|
	* \| \|
	* (err?) Y --->-------->--------->+ \|
	* \| \| \\|/
	* ACTION <set_values> \| \|
	* \| \| \|
	* (err?) Y >---------+ \\|/ \|
	* \| \| \| \|
	* +++ [consistency_checks] \| \| \|
	* \| \\|/ \| \|
	* UNDO (err?) Y >-------[undo]-------->+ \|
	* \| \| \|
	* [reversible_commit] \| \|
	* +++ \| \| \\|/
	* (err?) Y >--[reverse_commit] \| \|
	* \| \| \| \|
	* COMMIT <final_commit> \| \| \|
	* \| \| \| \|
	* (err?) Y >--[log msg] \| \|
	* \| \| \| \|
	* \| \\|/ \\|/ \|
	* \| <-----------<+---<-----------+ \|
	* \\|/ \|
	* FREE [undo_cleanup] \|
	* \| \\|/
	* \|<--------------<-----------------+
	* \\|/
	* [post_request]
	*/
	</pre>

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