[linrad] Re: Testing MAP65 v0.8

[Rick Kunath]

Stan wrote:

Hello Rick,

can you point me to some specific models for managed switches, so I can 
read up ?


This should get you started:

http://www.ctrlink.com/managed_features.htm

There are also some really good docs available on Cisco's site after you 
register.


The good stuff is Cisco gear, and has a wide range of prices, depending 
on whether you are looking at a high-speed backbone app or just wiring 
closet use. Some of the stuff at Cisco is pretty reasonably priced. Ebay 
has better deals on used Cisco gear


There are a wide variety of manufacturers out there, but again the best 
is Cisco IMHO, but almost anything with IGMP snooping will handle 
segmentation of multicast traffic.


There are some pretty good deals on used gear on Ebay, some even cheaper 
than a do-nothing typical consumer switch in a plastic case.


Rick Kunath, k9ao

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[linrad] Re: Testing MAP65 v0.8

[Rick Kunath]

Joe Taylor wrote:

My earlier problem with dropped multicast packets seems to be fixed in 
MAP65 v0.8.  However, when running the Linrad-MAP65 combination on two 
separate computers I still have some network-related problems.  Perhaps 
someone on this list who knows much more than I about networking can help.


My computer network looks like this:


ADSL  10 Mb/s  -- Computer_A
DSL -- Modem -- Ethernet -- Computer_B
  Hub|
   -- Computer_C

Three computers are connected to a 10 Mb/s Ethernet Hub.


Have you considered replacing the hub with a 100 Mbps full-duplex 
Ethernet switch? There are many advantages in this over a hub.


Computer_A is 
my XYL's machine.  Computer_B runs Windows 2000 Pro, and Computer_C runs 
Linux (presently the Kubuntu 6.06 distribution).  In addition to the 
connections of all three machines to the hub, a crossover cable makes a 
direct 100 Mb/s connection between computers B and C.


The ethernet interfaces on B and C appear to be configured correctly.  
On Linux they appear as eth0 and eth1 (occasionally they boot up as eth0 
and eth2, I don't know why???).


This is configurable, generally, and should be fixed if you intend to 
use interface based static routes. Check here for more info on iftab 
(/etc/iftab):


http://linux.die.net/man/5/iftab

 Connections to the Hub are assigned 
dynamic IP addresses;


I assume these addresses are in the 192.168.1.x range?

I assigned hard-coded addresses 192.168.10.12 and 
192.168.10.13 for the direct inter-machine connection

between B and C.

I can use the 100 Mb/s direct line for many purposes.  I can ping over 
it in either direction; I can ssh into Linux from  Windows; I can use 
Cygwin/X (as described above) to display Linux X programs on the Windows 
screen.


However, I cannot seem to persuade Windows 2000 Pro to accept multicast 
packets over the direct line.  When I run Linrad on computer C and MAP65 
on B, the multicast traffic is always received over the slow line, 
through the Hub. This uses most of the 10 Mb/s link's bandwidth, and my 
wife can't read her email when I'm on the air.  This is NOT GOOD.


An Ethernet switch would eliminate this, as traffic passing between two 
machines (B-C) does not use any bandwidth, nor is it seen, by any other 
machines. Internet access by machine A would be unaffected by a transfer 
occurring between machines B and C. Machine A would not see the traffic, 
nor would there be any contention for bandwidth on it's connection 
because of the B-C traffic.


By default the multicast traffic generated by Computer_C goes to eth0.  
I can use the Linux route command to explicitly tell the system to use 
eth0:


# route add -net 224.0.0.0 netmask 224.0.0.0 dev eth0

This works fine (but of course, still sends the heavy multicast traffic 
through the hub).  If I remove this routing instruction and instead enter


# route add -net 224.0.0.0 netmask 224.0.0.0 dev eth1

the multicast data are not received by MAP65 running on the other machine.

If I unplug the crossover cable from the Windows machine and instead 
plug it into a laptop running Win/XP, the laptop receives the multicast 
packets without a problem.


Thus, it would seem that the problem must be in my setup of the Win2k 
machine -- the one with two ethernet interfaces. Can anyone shed any 
light on this situation for me?


Would there be sufficient bandwidth in a 100baseTx connection (100 Mbps 
full-duplex) to handle both of the networking streams, i.e. the hub and 
the direct stream? If so, replacing the inefficient hub with a faster 
switch, thus confining network traffic to only the ports of the involved 
machines, might solve the issue. This might allow you to eliminate the 
direct connection between machines B and C.


As to W2k the unicast and multicast routes are handled in separate 
tables, check here for more info:


http://www.microsoft.com/technet/prodtechnol/windows2000serv/reskit/intwork/inaf_mul_hwmc.mspx?mfr=true

Hope some of this is of some use :)

Rick Kunath, k9ao



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[linrad] Re: FTP

[Rick Kunath]

Leif Asbrink wrote:

I have happily been using FTP to move files between 
computers although I have only been able to get it 
running on a few systems. (Red Hat 9 and Debian Etch)


After upgrading Debian I can no longer FTP.
This is the message:
500 OOPS: cannot locate user entry:ftpsecure

 


Snip


I did search the Internet, but after reading a lot
of things meaning nothing to me I now try the Linrad
list for assistance. Any ideas? 

 


Leif,

Have you thought about avoiding FTP altogether and using ssh instead? 
This works without the use of an FTP server altogether.


http://en.wikipedia.org/wiki/SSH_file_transfer_protocol

doing: sftp:// instead is what I do here.

fish:// is a less secure alternative also.

http://en.wikipedia.org/wiki/Secure_copy

Both of these work without messing about with an FTP server at all. I 
prefer sftp and use it exclusively to move files around here on my local 
LAN as well as across the Internet to other remote file servers. Both of 
these methods use an existing user account, so you drop the files into 
some existing users file space on the remote machine. If you need 
additional security, because these use ssh, you can use ssh keys for 
additional security. I don't on my local LAN which I have complete 
control over, but do for the remote machines.


These things should be built-in to any modern Linux distro. Most of the 
time, they just work out of the box.


Rick Kunath

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[linrad] Re: Debian Etch

[Rick Kunath]

Leif Asbrink wrote:


1) Mount the hard disk on the second IDE bus
so it becomes /dev/hdc

2) Put something that works as /dev/hda (I used a
hard disk with RedHat 9 on it)

3) Boot up and mount /dev/hdc1 as /mnt/hdc1

4) Type chroot /mnt/hdc1

5) Type apt-get install udev

6) Shut down, put the Debian Etch disk back 
as /dev/hda and reboot.


 


Leif,

I have had this happen a time or two on a Mandrake/Mandriva installation.

What worked for me was booting a Knoppix Live-CD and chrooting the 
partition with the problem. From there I was able to fix the issue, just 
as you did with your problem. I didn't have to open the box and do 
anything with the hardware.


I wonder if this might have worked for your problem too?

Rick Kunath


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