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Date:      Tue, 18 Aug 1998 14:57:10 -0700 (PDT)
From:      Doug White <dwhite@resnet.uoregon.edu>
To:        Kevin Kyeong-il CHOI <kevin.choi@cnes.fr>
Cc:        FreeBSD Question <freebsd-questions@FreeBSD.ORG>, FreeBSD Net <freebsd-net@FreeBSD.ORG>
Subject:   Re: Questions on TCPDUMP, TCP Window Size
Message-ID:  <Pine.BSF.4.00.9808181456000.19286-100000@resnet.uoregon.edu>
In-Reply-To: <000501bdca86$55eac6c0$52099584@pc-kichoi.cst.cnes.fr>

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On Tue, 18 Aug 1998, Kevin Kyeong-il CHOI wrote:

> Hi,
> 
> I have another question.
> I'm actually working on the TCP observation.
> I saw the article http://www.psc.edu/networking/perf_tune.html
> Then, I tried to change the system variables of FreeBSD 2.2.6
> to obtain a large TCP window size.
> 
> (1) First question.
> 	I want to make the RFC1323 works on FreeBSD 2.2.6.
> 	Is there any special procedure I need to do ?

As long as 'tcp_extensions=YES' in rc.conf, then those extensions are
enabled, yes.  You can confirm with the command:

sysctl net.inet.tcp.rfc1323

If it's set to 1 then it is enabled.

> (2) Second.
> 	Once the (1) question resolved, 
> 	How can I make TCP's option "Window Scale" work on
> 	any connection such as FTP ?

These optimizations are handled automatically, AFAIK.

> (3) Third
> 	TCPDUMP, as a real good utility to observe the traffic
> 	on TCP connection, I really want to use this. BUT, But,
> 	whenever I launch this "tcpdump [enter]", it tells me,
> 
> 	tcpdump: /dev/bpf0: Device not configured.
> 
> 	I tried to change chmod 666 /dev/bpf0, but no succeed.
> 
> 	What is the problem here ?

You need to build a new kernel with 

pseduo-device	bpfilter	4

in the config file.

Doug White                              | University of Oregon  
Internet:  dwhite@resnet.uoregon.edu    | Residence Networking Assistant
http://gladstone.uoregon.edu/~dwhite    | Computer Science Major


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