[uCsimm] ppp proxyarp on the uCsimm

From: David Saroff (saroff@zkcelltest.com)
Date: Thu Jan 27 2000 - 19:36:52 EST


Has anyone used PPP with proxyarp on the uCsimm? We are trying, without
success, and would appreciate any help, or confirmation of our problem.

The uCsimm's 10BaseT is connected to a hub with lots of other machines
including a Cobalt Cube running LINUX. The Ethernet is using the
192.168.1.x IPs for a private net using the netmask 255.255.255.0 . The
serial port the uCsimm is connected to a LINUX laptop, through its one
serial port /dev/ttyS0. We would like the uCSimm to proxyarp the laptop
onto the Ethernet.

>From a Konsole window in the laptop using minicom, we log into the
uCsimm. We start pppd in the uCsimm with the long command
pppd /dev/ttyS0 9600 netmask 255.255.255.0 proxyarp lock -crtscts
noauth 192.168.1.5:192.168.1.10 &
We use ^AQ to exit minicom without reseting the serial port.

We start pppd running in the linux laptop from a second Konsole window,
with the command
pppd /dev/ttyS0 9600 &

The ppp options on the laptop are in /etc/ppp/options as follows
 -crtscts
 defaultroute
 192.168.1.10:192.168.1.5
netmask 255.255.255.0
local
:

This partly works. Now the LINUX in the laptop shows a running ppp link.
By typing ifconfig we see tranmitted and received packets.

lo Link encap:Local Loopback
          inet addr:127.0.0.1 Mask:255.0.0.0
          UP LOOPBACK RUNNING MTU:3924 Metric:1
          RX packets:13 errors:0 dropped:0 overruns:0 frame:0
          TX packets:13 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0

ppp0 Link encap:Point-to-Point Protocol
          inet addr:192.168.1.10 P-t-P:192.168.1.5
Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
          RX packets:112 errors:0 dropped:0 overruns:0 frame:0
          TX packets:114 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:10

The route command in the laptop shows

Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use
Iface
192.168.1.5 * 255.255.255.255 UH 0 0 0
ppp0
127.0.0.0 * 255.0.0.0 U 0 0 0
lo
default 192.168.1.5 0.0.0.0 UG 0 0 0
ppp0

We can ping the simm from the laptop. We can see the web page in the
flash of the uCsimm from the laptop running Netscape. But we can't ping
machines on the ethernet on the other side of the uCsimm. So it seems
that the proxyarp is not working, and the TCP/IP packets are not getting
to the other side.

David Saroff
saroff@zkcelltest.com

Chris Adler
adler@zkcelltest.com

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