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RE: FreeBSD TCP/IP stack and sysctl


> You can look at the sysctl test
> (packages/net/bsd_tcpip/current/tests/sysctl1.c).  Or,
> here's an example of turning off rfc1323 support using
> sysctlbyname
> 
> int OldValue;
> 	int NewValue;
> 	size_t OldValueLength = sizeof(int);
> 	// Turn off RFC1323 support
> 	NewValue = 0;     // Disable
> 	sysctlbyname("net.inet.tcp.rfc1323", &OldValue,
> &OldValueLength, &NewValue, sizeof(int));
> 

Thanks... that's great.  I did look a little at sysctl1.c, but that seemed
to me (not knowing anything at all about sysctl) like it was manipulating
some sort of locally constructed MIB, rather than the MIB for the TCP stack.
But I'll look at it more carefully again.

Can I ask how you came up with the name "net.inet.tcp.rfc1323"?

The only name I could come up with for the retransmit timer was
"rexmit_min", which, from inference from your code, I would probably try
something like "net.inet.tcp.rexmit_min".  Is there a central list of MIB
names someplace?  (Even typical examples would be fine).


Thanks again for any and all pointers...

--wpd

> 
> --- "Doyle, Patrick" <WPD@dtccom.com> wrote:
> 
> > Can anybody point me at an example of using the
> > 'sysctl()' API of the
> > FreeBSD stack to adjust TCP parameters? 
> > Specifically, I would like to
> > shorten the retransmit timeout and lengthen the ACK
> > timeout.  (This is on a
> > dedicated PPP link between two devices).  I poked
> > around a little bit and
> > see that I can change the retransmit timeout -- I
> > haven't looked for how to
> > change the ACK timeout (if it is even possible).  I
> > just don't know where to
> > start with the 'sysctl()' function, having never
> > used it before.  If worse
> > comes to worse, I'll just change the variable
> > manually outside of the
> > sysctl() mechanism, but I figured I would start by
> > at least pretending to
> > follow the rules :-)
> > 
> > All pointers will be gratefully accepted...
> > 
> > --wpd
> > 
> > 
> > Patrick Doyle
> > DSP Design Engineer
> > (603) 546-2179
> > 
> >  
> > 
> > This communication is from DTC Communications, Inc.
> > and is intended to be
> > confidential and solely for the use of the persons
> > or entities addressed
> > above.  If you are not an intended recipient, be
> > aware that the information
> > contained herein may be protected from unauthorized
> > use by privilege or law,
> > and any copying, distribution, disclosure, or other
> > use of this information
> > is prohibited.  If you have received this
> > communication in error, please
> > contact the sender by return e-mail or telephone the
> > above number
> > immediately and delete or destroy all copies.  Thank
> > you for your
> > cooperation.
> > 
> >  
> > 
> > 
> > -- 
> > Before posting, please read the FAQ:
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> > 
> 
> 
> 
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Patrick Doyle
DSP Design Engineer
(603) 546-2179

 

This communication is from DTC Communications, Inc. and is intended to be
confidential and solely for the use of the persons or entities addressed
above.  If you are not an intended recipient, be aware that the information
contained herein may be protected from unauthorized use by privilege or law,
and any copying, distribution, disclosure, or other use of this information
is prohibited.  If you have received this communication in error, please
contact the sender by return e-mail or telephone the above number
immediately and delete or destroy all copies.  Thank you for your
cooperation.

 



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