[ILUG] Proxy arp problems

[Kenn Humborg]

I've got a machine atlas.bluetree.ie, with a pppd listening on
one of the serial ports, connected to a Palm V.  The pppd
hands out the address dialup-0.bluetree.ie to the remote
device.

This is the pppd command line:

   /usr/sbin/pppd ttyS0 57600 -detach proxyarp \
      passive local crtscts lock :dialup-0
      noauth ms-dns atlas


Before I connect from the Palm, the arp cache has no entry
for dialup-0.  After I connect from the Palm, arp -a shows:

[root at atlas /root]# arp -a...
dialup-0.bluetree.ie (192.168.3.250) at * PERM PUP on eth0
[root at atlas /root]#

This doesn't look right.  If I try to ping dialup-0 from
another machine, the other machine gets this entry in its
arp table:

[root at cerberus /root]# arp -a
Address                 HWtype  HWaddress           Flags Mask
Iface
...
dialup-0.bluetree.ie    ether   00:00:00:00:00:00         *
eth0
[root at cerberus /root]#

This definitely isn't right.  When I disconnect from the Palm,
the arp entry is removed from atlas, as expected.

So let's try manually adding the arp entry:

[root at atlas /root]# arp -s dialup-0 00:40:95:01:77:1B
[root at atlas /root]# arp -a
dialup-0.bluetree.ie (192.168.3.250) at 00:40:95:01:77:1B [ether] PERM on
eth0
...

But that won't get published to other machines.  So let's try
deleting this entry and adding a pub entry:

[root at atlas /root]# arp -a
dialup-0.bluetree.ie (192.168.3.250) at <incomplete> on eth0
...
dialup-0.bluetree.ie (192.168.3.250) at * PERM PUP on eth0
[root at atlas /root]#

What the hell is going on here?

RH6.0, net-tools-1.52-2

Later,
Kenn