Funky LAN Weirdness (pretty cool, actually)

Funky LAN Weirdness (pretty cool, actually)

Post by Tiny Human Ferre » Sun, 27 Aug 2000 04:00:00



Hi, thought I would share...

I've got an AMD K6/2 running Slackware 7 (with boatloads of other fun stuff
including SSH and tcp_wrappers and other assorted functional paranoia) and
it fronts for the house LAN, using a combination of ipchains, SOCKS5 and
some serious weirdness in /etc/rc.d/rc.inet*

Okay, for a long time I was happy serving the house LAN at 10mbps, since mom
upstairs had only a Mac LC-III with a 10mbps card. In any case, the
connection to the InterNet is only 28.8K baud. But in preparation for an
SDSL connection, I built another box, Athlon 600MHz with 256 megs and a
truly ridiculous 120 gigs of drivespace. From the start, it had two SMC
EZNet 10/100 ethernet cards installed. Getting those to run was a bit
problematic, since all that differs about them is their Mac (hardware)
address.

Also, mom got a new iMac, which is actually a very sweet machine, lovely
monitor on it, G3, MacOS 9 PowerPC. And it's got 10/100 ethernet as well --
and it runs the wonderful freeware MI/X X-windows for the Mac. I've
long-since installed the NetaTalk Appletalk encapsulated over IP, which is
great -- I was able to offload all of mom's old files onto my Linux box via
ethernet, and reinstall them onto her new machine. Better than swapping SCSI
drives, not possible in this case since the iMac hasn't got anyplace for the
old LC-III 80megger and only has USB and Ethernet 10/100 for serial-type
I/O.

Here is the funky weirdness, I like what it's doing but would like to know
_why_.

I installed an SMC EZNet 10/100 into the Slackware box, and rebuilt the
2.2.14 kernel to support the card -- it needed the "rtl8139" driver,
available somewhere under http://www.veryComputer.com/ -- yet another great driver by
Don Becker.

It was necessary to "clone" the /etc/rc.d/rc.inet1 file. rc.inet1
initializes the old 10mbps NE2000 card, which had to be compiled directly
into the kernel, as 10.0.0.1 on 255.0.0.0 net as eth0. After that
stabilizes, I start up /etc.rc.d/rc.local to crank up the appletalk
encapsulation, and then the cloned "rc.inet3" loads the module driver for
the SMC card and initializes it as 10.0.0.4 on 255.0.0.0 as eth1.

Here's the weirdness. Trying to telnet to the Athlon box (10.0.0.5) I get
connected to the login port but it won't activate, and just sits, if eth0 is
turned off. If eth0 and eth1 are both on, it logs in fine.

Here's the _major_ weirdness... let's say I have eth0 and eth1 up, and
telnet 10.0.0.5, and do something like `xv -display 10.0.0.1:0.0
whatever.jpg` and I'm watching tcpdump on both eth0 and eth1, almost all of
the traffic comes over 10.0.0.4/eth1. This is way cool. Even cooler is that
when the iMac cranks up as 10.0.0.6, it _also_ gets the initial message of
"who has localhost" across 10.0.0.1 (it's got that set in its TCP/IP
controls as both router and nameserver) but when any TCP (as opposed to UDP
or RAW) packets get sent or received, they go over 10.0.0.4 at 100mbps. This
includes the Appletalk encapsulated over IP. It also includes the "X"
connections, so my mom's Mac can now provide exceptional quality displays of
apps executing on either or both Linux boxes, in ver near real-time.

All of this IP on the house LAN goes to an el-cheapo but surprisingly good
LinkSys NH1005 five-port 10/100 hub.

Amazingly, hardly any traffic remains on the 10mbps 10.0.0.1 eth0 connection
-- all there is appears to be udp and is mostly "who" traffic -- but
insanely enough, it has to be connected for the 10.0.0.4 connection to work.

BTW, the second SMC card on the Athlon box will be eventually going to a
SDSL router, which will connect a few other world-routable addressed as
well, via SDSL. The new, commercial, domain will be "earthops.net" as
opposed to the non-commercial "earthops.org", which will not pass traffic as
a mini-NAP as it will be connected only via 28.8K baud modem.

I'm not sure if it's because I compiled in the experimental load-balancing
and bridge support, but I suspect this may have something to do with it.

Submitted for your cogitation and amu*t...

--
                    "We look through a glass but darkly:
                 What we see is more colored by our beliefs,
               than what we believe is colored by what we see."

 
 
 

1. Pretty strange 'n funky bug !

Hi everybody !

I experienced a pretty strange bug with XFree86.  It might already have
been reported.  If so, please forgive me.  BTW, I am a newbie and I am
posting from work since I have not succeed I connecting my Linux system at
home to the Internet ("Kernel lack PPP support"... anybody willing to do
some handholding in compiling a new kernel ? :).  I don't have all the
detail at hand, but if somebody is interested in my experience, contact me
and ask for the specific detail you need (kernel version, X server version,
etc.) and I'll get them for you.

I am using Red Hat 5.0, gotten from the Info-Magic 6 CD set of february 98.
 My video card is a S3 Trio 64V+, so the RedHat install choosed the S3 X
server.  My monitor is Samsung SyncMaster 3Ne, wich I choosed from a list.

FNWM acted quit strangely.  It seem that the display was offset by a 1/4"
to the left and  wrapped around to the right.  It's hard to explain, you
really have to see it to get it.  For example, the Start button in the
lower left corner of the screen was cut in half, the last 3/4 at the right
place in the lower left corner and the first 1/4 in the lower right corner.
 The mouse was having it right though, so you had to click 1/4" to the
right of the actual place you wanted to click to compensate for the offset
(i.e. to click the X button that close the windows in the far right corner,
you had to click a 1/4" right, actually outside the windows) .  The mouse
cursor also reacted to GUI element (i.e. windows border) a 1/4" to the
right.  I corrected the problem by choosing the "Generic monitor" in X
setup; it is now working fine.

I am wondering if this is a software bug or a sync/calibration problem with
the monitor.  What's your opinion ?

Etienne Goyer
stalphon at globetrotter dot qc dot ca    

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