[Techtalk] 2nd networking question

[Maria Blackmore]

On Mon, 2 Sep 2002, BUNTER MATTHEW wrote:
> I agree about the dropping of ICMP packets. If needed one could just setup
> a firewall rule to limit the amount of ICMP packets within a certain time
> I think.

Indeed, in fact a lot of networks do this, albeit using something with
considerably more oompf than a linux box

> Thanks for the info as well, but I still haven't found where one can see
> the TCP Window size in a Linux config file.

you can find all the stuff for this in /proc/sys/net/ipv4/ and
/proc/sys/net/core/

These are a representation of how the kernel is setup (sysctl), you can
of course write to these files to change the parameters

They appear to be documented here
http://www.linuxhq.com/kernel/v2.4/doc/networking/ip-sysctl.txt.html

but for example, you could do something like (borrowed from
http://www-didc.lbl.gov/tcp-wan.html)

echo 8388608 > /proc/sys/net/core/wmem_max
echo 8388608 > /proc/sys/net/core/rmem_max
echo "4096 87380 4194304" >  /proc/sys/net/ipv4/tcp_rmem
echo "4096 65536 4194304" > /proc/sys/net/ipv4/tcp_wmem
echo "4194304 4194304 4194304" > /proc/sys/net/ipv4/tcp_mem

you can put this in your init scripts to make sure that these are set
every time you boot

There seems to be some docs on TCP windowing and auto-adjustment here:
http://www.csm.ornl.gov/~dunigan/netperf/auto.html#linux


However, back to your problem, do either of the machines have any packet
filtering on them at all, or indeed anything different from a plain
vanilla setup?  What sort of network cards are they (from the point of
view of drivers) and is there anything in between the two computers apart
from a piece of network cable (anything at all, switch, hub, router,
anything).  Also are there any other machines on the same network? are
they having any problems?  eg a third machine exchanging traffic between
the either of the two with the issues?

> Matt (who is sorry it took so long for him to realise HE was one of the
> ones top-posting)

:)

I wonder if I could ask you to indent quotes too, please.  With a > or |
or similar, please?  thanks :)

Maria
meow