> > >Starting the SNMP Agent >
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> NAME="NET-SNMP-STARTING-THE-SNMP-AGENT">Starting the SNMP Agent > >A routine to instantiate and start the SNMP agent thread in the default
configuration is provided in
CLASS="FILENAME"
>PACKAGES/net/snmp/agent/VERSION/src/snmptask.c > > >It starts the snmpd thread at priority
CLASS="LITERAL"
>CYGPKG_NET_THREAD_PRIORITY+1 >
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). > BORDER="5"
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> > > CLASS="PROGRAMLISTING"
>#ifdef CYGPKG_SNMPAGENT
{
extern void cyg_net_snmp_init(void);
cyg_net_snmp_init();
}
#endif > > > > >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:
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> > > CLASS="PROGRAMLISTING"
>externC void (* CLASS="emphasis"
> CLASS="EMPHASIS"
>snmpd_reinit_function > >)( void ); > > > >
with a suitable function pointer. > >The entry point to the SNMP agent is
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> > > CLASS="PROGRAMLISTING"
>externC void CLASS="FUNCTION"
>snmpd >( void (* CLASS="emphasis"
> CLASS="EMPHASIS"
>initfunc > >)( void ) ); > > > >
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 CLASS="LITERAL"
>initfunc > parameter is the callback
function mentioned above — a NULL parameter there is safe and
obviously means no callback is registered. > >Note that if you call CLASS="LITERAL"
>snmpd(); > yourself and do
CLASS="emphasis"
> CLASS="EMPHASIS"
>not > > call CLASS="LITERAL"
>cyg_net_snmp_init(); > 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. > >Other APIs from the CLASS="LITERAL"
>snmpd > module are available,
specifically:
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> > > CLASS="PROGRAMLISTING"
>void CLASS="FUNCTION"
>SnmpdShutDown >(int CLASS="emphasis"
> CLASS="EMPHASIS"
>a > >); > > > >
which causes the CLASS="LITERAL"
>snmpd > to restart itself —
including the callback to your init function — as soon as possible. > >The parameter CLASS="emphasis"
> CLASS="EMPHASIS"
>a > > is ignored. It is there because in
CLASS="LITERAL"
>snmpd >'s “natural environment” this routine
is a CLASS="LITERAL"
>UNIX > signal handler. > >The helper functions in the network stack for managing
CLASS="LITERAL"
>DHCP >
leases will call CLASS="FUNCTION"
>SnmpdShutDown() >
when necessary, for example if network interfaces go down and/or come up
again. > > CLASS="NAVFOOTER"
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