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-><A
-NAME="NET-SNMP-STARTING-THE-SNMP-AGENT">Starting the SNMP Agent</H1
-><P
->A routine to instantiate and start the SNMP agent thread in the default
-configuration is provided in
-<TT
-CLASS="FILENAME"
->PACKAGES/net/snmp/agent/VERSION/src/snmptask.c</TT
-></P
-><P
->It starts the snmpd thread at priority
-<TT
-CLASS="LITERAL"
->CYGPKG_NET_THREAD_PRIORITY+1</TT
->
-by default, ie. one step less important than the TCP/IP stack service
-thread.
-It also statically creates and uses a very large stack of around 100
-KiloBytes.
-To use that convenience function, this code fragment may be copied (in
-plain C).</P
-><TABLE
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-><TR
-><TD
-><PRE
-CLASS="PROGRAMLISTING"
->#ifdef CYGPKG_SNMPAGENT
-{
- extern void cyg_net_snmp_init(void);
- cyg_net_snmp_init();
-
-}
-#endif</PRE
-></TD
-></TR
-></TABLE
-><P
->In case you need to perform initialization, for example setting up SNMPv3
-security features, when the snmp agent starts and every time it restarts,
-you can register a callback function by simply writing the global variable:
-<TABLE
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-><TR
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-><PRE
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->externC void (*<SPAN
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-><I
-CLASS="EMPHASIS"
->snmpd_reinit_function</I
-></SPAN
->)( void );</PRE
-></TD
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->
-with a suitable function pointer.</P
-><P
->The entry point to the SNMP agent is
-<TABLE
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-><TD
-><PRE
-CLASS="PROGRAMLISTING"
->externC void <TT
-CLASS="FUNCTION"
->snmpd</TT
->( void (*<SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->initfunc</I
-></SPAN
->)( void ) );</PRE
-></TD
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->
-so you can of course easily start it in a thread of your choice at another
-priority instead if required, after performing whatever other
-initialization your SNMP MIBs need. A larger than default stacksize is
-required. The <TT
-CLASS="LITERAL"
->initfunc</TT
-> parameter is the callback
-function mentioned above — a NULL parameter there is safe and
-obviously means no callback is registered.</P
-><P
->Note that if you call <TT
-CLASS="LITERAL"
->snmpd();</TT
-> yourself and do
-<SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->not</I
-></SPAN
-> call <TT
-CLASS="LITERAL"
->cyg_net_snmp_init();</TT
-> then
-that routine, global variable, and the default large stack will not be
-used. This is the recommended way control such features from your
-application; create and start the thread yourself at the appropriate
-moment.</P
-><P
->Other APIs from the <TT
-CLASS="LITERAL"
->snmpd</TT
-> module are available,
-specifically:
-<TABLE
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->void <TT
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->SnmpdShutDown</TT
->(int <SPAN
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-><I
-CLASS="EMPHASIS"
->a</I
-></SPAN
->);</PRE
-></TD
-></TR
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->
-which causes the <TT
-CLASS="LITERAL"
->snmpd</TT
-> to restart itself —
-including the callback to your init function — as soon as possible.</P
-><P
->The parameter <SPAN
-CLASS="emphasis"
-><I
-CLASS="EMPHASIS"
->a</I
-></SPAN
-> is ignored. It is there because in
-<TT
-CLASS="LITERAL"
->snmpd</TT
->'s “natural environment” this routine
-is a <TT
-CLASS="LITERAL"
->UNIX</TT
-> signal handler.</P
-><P
->The helper functions in the network stack for managing
-<TT
-CLASS="LITERAL"
->DHCP</TT
->
-leases will call <TT
-CLASS="FUNCTION"
->SnmpdShutDown()</TT
->
-when necessary, for example if network interfaces go down and/or come up
-again.</P
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